We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment. I've already put in GFCI
outlets in bathrooms, kitchen, garage, outdoor locations. So from a
people safety perspective I think that's about as good as we can do,
and grounding would not improve that situation.

Now for equipment, I'm thinking about a panel-based whole house surge
suppressor, since the lack of grounding will defeat any point-of-use
surge suppressors. There seem to be quite a few units available with
similar specs: clamping voltages in the 400-500V range, energy
dissipation on the order of 1000 joules, maximum current 50,000 amps,
5 ns response. One example is the Intermatic 1G1240R. These seem to
generally be described as sufficient for protecting appliances but the
vendors still recommend point-of-use surge suppressors for electronic
equipment.

There is also a product sold by Tytewadd, which clamps at 130V, maximum
current 10,000 amps, and 1.5 ns response. It is specifically
advertised as protection for "sensitive equipment". But... it has a
total energy dissipation of only 70 joules, far far less than the
previous class of units.

Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician to
rewire a couple outlets in key locations, and stick with power strip
surge suppressors?

-- Dave

wrote in message
ups.com...
We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment. I've already put in GFCI
outlets in bathrooms, kitchen, garage, outdoor locations. So from a
people safety perspective I think that's about as good as we can do,
and grounding would not improve that situation.

Now for equipment, I'm thinking about a panel-based whole house surge
suppressor, since the lack of grounding will defeat any point-of-use
surge suppressors. There seem to be quite a few units available with
similar specs: clamping voltages in the 400-500V range, energy
dissipation on the order of 1000 joules, maximum current 50,000 amps,
5 ns response. One example is the Intermatic 1G1240R. These seem to
generally be described as sufficient for protecting appliances but the
vendors still recommend point-of-use surge suppressors for electronic
equipment.

There is also a product sold by Tytewadd, which clamps at 130V, maximum
current 10,000 amps, and 1.5 ns response. It is specifically
advertised as protection for "sensitive equipment". But... it has a
total energy dissipation of only 70 joules, far far less than the
previous class of units.

Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician to
rewire a couple outlets in key locations, and stick with power strip
surge suppressors?

Whole-house surge suppression is a good idea and that is based on personal
experience.

130 volt clamp is too low. 70 joules is too low.

There was no Internet when I installed my first unit and I went to the best
electrical supply house in my vicinity and talked to those folks. Now, you
can Google this to death.

wrote:

We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment. I've already put in GFCI
outlets in bathrooms, kitchen, garage, outdoor locations. So from a
people safety perspective I think that's about as good as we can do,
and grounding would not improve that situation.

Now for equipment, I'm thinking about a panel-based whole house surge
suppressor, since the lack of grounding will defeat any point-of-use
surge suppressors. There seem to be quite a few units available with
similar specs: clamping voltages in the 400-500V range, energy
dissipation on the order of 1000 joules, maximum current 50,000 amps,
5 ns response. One example is the Intermatic 1G1240R. These seem to
generally be described as sufficient for protecting appliances but the
vendors still recommend point-of-use surge suppressors for electronic
equipment.

There is also a product sold by Tytewadd, which clamps at 130V, maximum
current 10,000 amps, and 1.5 ns response. It is specifically
advertised as protection for "sensitive equipment". But... it has a
total energy dissipation of only 70 joules, far far less than the
previous class of units.

Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician to
rewire a couple outlets in key locations, and stick with power strip
surge suppressors?

-- Dave

Lack of grounding will not "defeat" point of use suppressers. Those
suppressers will still act to suppress differential surges on the line
between neutral and hot which are most likely to cause damage to the
connected device.

Without a ground that can't do anything about common mode surges where
the same surge voltage is present on both the hot and neutral however
these surges are less likely to damage the connected device unless it
has a ground connection like a CATV connection.

Pete C.

Charles Schuler wrote:

Whole-house surge suppression is a good idea and that is based on personal
experience.

130 volt clamp is too low. 70 joules is too low.

There was no Internet when I installed my first unit and I went to the best
electrical supply house in my vicinity and talked to those folks. Now, you
can Google this to death.

I think I can safely say I've googled it to death already. I couldn't
find any information on the Tytewadd device except from the
manufacturer. Why is a low voltage clamp bad? I'd think that it would
be better to clamp as low as possible.

I asked a local electrician about installing a whole house surge
suppressor and he said he hadn't heard of them, and I can't find a
local supplier that stocks them. I guess that's because we're in a low
lightning risk area (we're lucky if we get one or two thunderstorms per
year), but it still seems like cheap insurance. On the other hand, if
these units are not effective for protecting electronic equipment, then
I'm back to square one.

-- Dave

Pete C. wrote:

Lack of grounding will not "defeat" point of use suppressers. Those
suppressers will still act to suppress differential surges on the line
between neutral and hot which are most likely to cause damage to the
connected device.

Hmmm. Some surge suppressor power strip vendors specifically say that
they offer no protection and no warranty when used in an ungrounded
outlet. Are you saying that they can shunt current between hot and
neutral in a differential surge? I thought that all surges were
shunted to ground?

-- Dave

Common mode surges are a most typical source of electronics damage.
Point of use (plug-in) protector would do what already exists inside
appliances. Appliance protection is typically so superior that a
surge, incapable of damaging that appliance, can still cause a plug-in
protector to smoke. This undersized (smoking) protector gets the naive
to promote more sales of a so profitable and ineffective product.

Take a $3 power strip. Add some $0.10 parts. Sell it for $20 or
$120 as a plug-in protector. Do anything possible to avoid discussing
THE most critical component in every protection 'system': earth ground.
Amazing how word association (surge protector = surge protection)
replaces science to promote myths.

Appreciate further problems with plug-in protectors even 20+ years
after UL1449 was created (because this happened so often). Would you
put these on a rug or on a desk full of papers?
http://www.westwhitelandfire.com/Art...Protectors.pdf
http://www.hanford.gov/rl/?page=556&parent=554
http://www.zerosurge.com/HTML/movs.html
http://www.nmsu.edu/~safety/programs...tectorfire.htm

Earthing is the most essential component in every protector system.
Industry professionals, your telco, AC electric companies, commercial
radio and TV broadcasters, ham radio operators, and even Ben Franklin
demonstrated this all so necessary 'system' component. Do they install
plug-in protectors? Of course not. No earth ground means no effective
protection. True 70 years ago. Now essential for homes due to
something new - the transistor.

Yes, lack of grounding will not defeat point of use suppressers
because those grossly overpriced protectors don't even claim to protect
from a typically destructive transient. But then don't take my word
for it. Where does it list each type of transient with numbers to
define protection? It does not. They hope you will 'assume' it is a
complete protection solution. Assuming is what recommends plug-in
protectors - myths based only on assumptions that even the manufacturer
does not dare to claim.

How to quickly identify an ineffective protector: 1) No dedicated
earthing wire. 2) Manufacturer avoids all discussion about earthing.

Effective protection earths before transients enter the building - so
that transients do not overwhelm protection already inside appliances.
Transients that don't enter a building therefore do not find
destructive earthing paths everywhere inside that building.

Effective protectors are also sold under names of responsible
manufacturers such as Square D, Cutler-Hammer, Siemens, Intermatic,
Leviton, and GE. Effective protector solutions will not be found in
Radio Shack, Sears, Staples, Best Buy, K-mart, Office Max, Bed Bath &
Beyond, Wal-mart, or the grocery store. How do you know? Where is
that all so necessary earthing wire?

Solutions are sold in Lowes, Home Depot, and most any electrical
supply house. They have been necessary since the 1970s - when
transistors began appearing in homes. Home earthing system must both
meet and exceed post 1990 National Electrical Code requirements.

Above is installed for secondary protection. Primary protection
'system' should be inspected:
http://www.tvtower.com/fpl.html

A 'whole house' protector is protection for about $1 per appliance.
Superior solution - and it even costs less money. A protector is only
as effective as its earth ground.

Pete C. wrote:
Lack of grounding will not "defeat" point of use suppressers. Those
suppressers will still act to suppress differential surges on the line
between neutral and hot which are most likely to cause damage to the
connected device.

Without a ground that can't do anything about common mode surges where
the same surge voltage is present on both the hot and neutral however
these surges are less likely to damage the connected device unless it
has a ground connection like a CATV connection.

wrote:
We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment. I've already put in
GFCI outlets in bathrooms, kitchen, garage, outdoor locations. So
from a people safety perspective I think that's about as good as we
can do, and grounding would not improve that situation.

Now for equipment, I'm thinking about a panel-based whole house surge
suppressor, since the lack of grounding will defeat any point-of-use
surge suppressors. There seem to be quite a few units available with
similar specs: clamping voltages in the 400-500V range, energy
dissipation on the order of 1000 joules, maximum current 50,000 amps,
5 ns response. One example is the Intermatic 1G1240R. These seem to
generally be described as sufficient for protecting appliances but the
vendors still recommend point-of-use surge suppressors for electronic
equipment.

There is also a product sold by Tytewadd, which clamps at 130V,
maximum current 10,000 amps, and 1.5 ns response. It is specifically
advertised as protection for "sensitive equipment". But... it has a
total energy dissipation of only 70 joules, far far less than the
previous class of units.

Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician to
rewire a couple outlets in key locations, and stick with power strip
surge suppressors?

-- Dave

130V ac is too low a voltage for a clamp; line voltages can go to 132Vac for
short periods of time and be "in spec". Are you sure you read that right?
Sounds more like someting for a lab environ or such. Anyway, since you're
talking suppressors and not conditioners, that's too low a voltage rating
for everyday use 24/7; you'll spend all your time wondering why it's
alerting.

Joules are the important number; the higher the better. 70 joules is next
to useless for a whole-house arrangement. I'm surprised the numbers don't
go higher than 1,000 too, but haven't fiddled in that market for some time.
Joules are a measure of the total power it can consume while "protecting"
the house, so get as high as you can.

Any timng in the nanoseconds range should be OK. You'll probably find that
as the joules go up, the nanoseconds time gets longer, too, and that's
normal within reason. If there is mention of zero-crossing design too,
that's another good feature.

Amps and/or Volts alone aren't very accurate measures of the quality of a
suppressor; so pay attention to the joules numbers the most.

And just a short reminder: NOTHING can protect you against a nearby
lightning hit, so watch out for too much marketing hype in that vein. That
said however, lightning is often the cause of substantial spikes and surges
on the power lines; the transofrmer out on the pole helps smooth thouse out
a lot, but if it's a close enough hit, nothing will "protect" against it.

That's great and logical actions for the GFCI work you did. Sounds like
it's to code and you caught the important places to have them.

An EXCEPTION for the 2-wire outlets is going to be for your computer and
other electronic equipment around the house. IFF a product is sold with a
3-wire cord, then the 3-wires are necessary for a myriad of reasons ranging
from UL type safety requirements to FCC RF requirements.
You might want to give some thought to providing the 3rd wire (earth
ground) for the outlets where you connect your computer, TV, Stereo, things
like that. Computers and their peripherals in particular depend on the
ground connection for a lot of things.

This one's an important safety consideration: All 2-wire outlets must
have the polarity type openings, two different sizes in other words; shorter
one is hot, longer one is neutral. And of course the plugs that go in them
must conform also, in case you have any equipment where a plug or cord has
been replaced on it.
Not all plugs have the two different sized blades on them; they may be
what's called Class 2 devices; in these cases it doesn't matter which way
they're plugged in; there is no polarity to worry about.
IFF there is a third wire though, there really does need to be a ground
in the outlet for that third wire to connect to.

HTH,
Pop`

Pop` wrote:

An EXCEPTION for the 2-wire outlets is going to be for your computer and
other electronic equipment around the house. IFF a product is sold with a
3-wire cord, then the 3-wires are necessary for a myriad of reasons ranging
from UL type safety requirements to FCC RF requirements.
You might want to give some thought to providing the 3rd wire (earth
ground) for the outlets where you connect your computer, TV, Stereo, things
like that. Computers and their peripherals in particular depend on the
ground connection for a lot of things.

Hmmm. If this is the case then why are GFCI outlets allowed on
ungrounded circuits at all? It would be easy enough to manufacture a
2-wire GFCI outlet with no ground pin for retrofits, and an ungrounded
GFCI is just begging to receive a 3-prong plug. My understanding was
that purely from a safety perspective an ungrounded GFCI outlet was as
safe as a grounded one even when used with a 3-wire device.

-- Dave

wrote:

Pete C. wrote:

Lack of grounding will not "defeat" point of use suppressers. Those
suppressers will still act to suppress differential surges on the line
between neutral and hot which are most likely to cause damage to the
connected device.

Hmmm. Some surge suppressor power strip vendors specifically say that
they offer no protection and no warranty when used in an ungrounded
outlet. Are you saying that they can shunt current between hot and
neutral in a differential surge? I thought that all surges were
shunted to ground?

-- Dave

A typical cheap suppresser has three MOVs, one hot to ground, one
neutral to ground and one hot to neutral. Obviously the hot to neutral
MOV can clamp transients that are differential across the hot and
neutral regardless of the presence of a ground connection. Suppressers
using gas discharge tubes would be similar.

If the surge is common mode, raising the voltage on both hot and neutral
and the device connected has no ground connection anywhere like a CATV
connection, then the entire device will jump to the higher potential
which should cause no damage. The hot-neutral suppresser would still
attempt to clamp any excess imbalance so the device should not see any
effective over voltage unless the surge exceeds the suppressers clamping
capacity.

As for warranty, certainly the suppresser can't work to it's full design
capacity without a ground so they don't want to warranty anything. That
doesn't mean that the suppresser will be useless without a ground.

Pete C.

w_tom spake thus:

Common mode surges are a most typical source of electronics damage.
Point of use (plug-in) protector would do what already exists inside
appliances. Appliance protection is typically so superior that a
surge, incapable of damaging that appliance, can still cause a plug-in
protector to smoke. This undersized (smoking) protector gets the naive
to promote more sales of a so profitable and ineffective product.

Take a $3 power strip. Add some $0.10 parts. Sell it for $20 or
$120 as a plug-in protector. Do anything possible to avoid discussing
THE most critical component in every protection 'system': earth ground.

[lotsa good stuff grounding snipped]

'Scuse me just a second, but even though the O.P. referred to their
house as having "older two-wire ungrounded wiring", that doesn't mean
that their service is *ungrounded*, only that there's not a separate
ground and neutral, correct? So their electrical service *is* grounded
(should be, anyhow).


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

w_tom wrote:

Common mode surges are a most typical source of electronics damage.

useless bogus blather deleted

There you go again with your nonsense.

Care to explain how a common mode surge can damage a device that has no
ground connection?

A device with only two electrical connections, hot and neutral, does not
care in the least what the voltage on these lines is relative to ground.
0 Volts and 120 Volts or 12,000 Volts and 12,120V look *exactly* the
same to the device. Unless the surge is high enough to blow through the
insulation of the devices enclosure and arc to ground it is absolutely
irrelevant to the health of the device.

Pete C.

wrote:
I asked a local electrician about installing a whole house surge
suppressor and he said he hadn't heard of them, and I can't find a
local supplier that stocks them.

Here's twelve:

http://search.ebay.com/search/search...e&category 0=

Home Depot and Loews both (sometimes) carry them.

A house using two wire receptacles would be wired for pre-1990
earthing requirements. One need not ground wall receptacles to have
superior surge protection. But earthing at the AC mains box must be
upgraded to post 1990 code AND meet additional requirements defined in
the previous post.

This proper earthing and a 'whole house' protector are less
expensive, far more effective, AND enhances household human safety.
All this without massive rewiring of a house for three wire
receptacles. Notice a critically important parameter for surge
protection. That earthing must be short (ie 'less than 10 feet').
What is necessary to install an effective 'whole house' protector?
That household earthing must be upgraded to meet and to exceed post
1990 NEC code requirements. Superior protection regardless of two wire
or three wire receptacles.

Meanwhile, too many homes do not even have earthing that meets those
1960 earthing requirements. Too many see lights working - then assume
everything is just fine. One home even exploded because that missing
earthing (and other factors) caused electricity to conduct through the
gas meter.

Not only is 1960 earthing typically not sufficient for transistor
protection. Too often, earthing is compromised as to not provide human
protection. That earthing must both meet and 'exceed' post 1990 code
requirements. To better appreciate why, learn about 'wire impedance'.
Not resistance - impedance.

David Nebenzahl wrote:
[lotsa good stuff grounding snipped]

'Scuse me just a second, but even though the O.P. referred to their
house as having "older two-wire ungrounded wiring", that doesn't mean
that their service is *ungrounded*, only that there's not a separate
ground and neutral, correct? So their electrical service *is* grounded
(should be, anyhow).

wrote:
Hmmm. If this is the case then why are GFCI outlets allowed on
ungrounded circuits at all? It would be easy enough to manufacture a
2-wire GFCI outlet with no ground pin for retrofits, and an ungrounded
GFCI is just begging to receive a 3-prong plug. My understanding was
that purely from a safety perspective an ungrounded GFCI outlet was as
safe as a grounded one even when used with a 3-wire device.

Do not confuse human safety requirements with other requirements.
National Electrical Code only addresses human safety issues. GFCI with
only two wires and with the label "No Equipment Ground" (or whatever
the exact wording is) does provide human safety (if an unearthed surge
does not enter the house and damage that GFCI).

Many wires do (perform) multiple functions. Again, earthing wire
must meet human safety requirements (NEC) and must exceed those
requirements to provide transistor safety.

Code permits GFCI because code only addresses human safety issues.

wrote:
Pop` wrote:

An EXCEPTION for the 2-wire outlets is going to be for your
computer and other electronic equipment around the house. IFF a
product is sold with a 3-wire cord, then the 3-wires are necessary
for a myriad of reasons ranging from UL type safety requirements to
FCC RF requirements. You might want to give some thought to
providing the 3rd wire (earth ground) for the outlets where you
connect your computer, TV, Stereo, things like that. Computers and
their peripherals in particular depend on the ground connection for
a lot of things.

Hmmm. If this is the case then why are GFCI outlets allowed on
ungrounded circuits at all? It would be easy enough to manufacture a
2-wire GFCI outlet with no ground pin for retrofits, and an ungrounded
GFCI is just begging to receive a 3-prong plug. My understanding was

that purely from a safety perspective an ungrounded GFCI outlet was as
safe as a grounded one even when used with a 3-wire device.

True, w/r to personal safety of living beings.


-- Dave

They're "allowed" because they do what they're designed to do on a 2-wire
circuit. The ground however is still missing, and non-functional. The
"safety" issue isn't toward people; it's toward reliability and
functionality for areas where the ground is necessary for whatever reason,
such as computers and surge protectors. Without the third wire, surge
protection exists only between the hot & neutral; the hot & neutral
connections to ground then are ineffective and cannot divert surges etc to
ground as they are designed to do. So, the degree of protection suffers.

An ungrounded GFCI is no 'safer' than a standard outlet w/r to the third
wire necessity or lack of it. The safety in this case is to equipment, not
people necessarily. I don't know the wording, but I'm pretty sure even an
ungrounded GFCI is supposed to be labelled as such; because of the three
receptacles per outlet. Actually, that's why a lot of people go for the
GFCI breakers right in the panels. Plus, there you don't have to worry
about whether the GFCI is "first" in the line or not; it has to be there.

HTH
Pop`

Pete C. wrote:
wrote:

Pete C. wrote:

Lack of grounding will not "defeat" point of use suppressers. Those
suppressers will still act to suppress differential surges on the
line between neutral and hot which are most likely to cause damage
to the connected device.

Hmmm. Some surge suppressor power strip vendors specifically say
that they offer no protection and no warranty when used in an
ungrounded outlet. Are you saying that they can shunt current
between hot and neutral in a differential surge? I thought that all
surges were shunted to ground?

-- Dave

A typical cheap suppresser has three MOVs, one hot to ground, one
neutral to ground and one hot to neutral. Obviously the hot to neutral
MOV can clamp transients that are differential across the hot and
neutral regardless of the presence of a ground connection. Suppressers
using gas discharge tubes would be similar.

If the surge is common mode, raising the voltage on both hot and
neutral and the device connected has no ground connection anywhere
like a CATV connection, then the entire device will jump to the
higher potential which should cause no damage. The hot-neutral
suppresser would still attempt to clamp any excess imbalance so the
device should not see any effective over voltage unless the surge
exceeds the suppressers clamping capacity.

As for warranty, certainly the suppresser can't work to it's full
design capacity without a ground so they don't want to warranty
anything. That doesn't mean that the suppresser will be useless
without a ground.

Pete C.

True, but if you want any common-mode protection type event in particular,
which is what happens with lightning or any other signals that hits both
wires "out there", then you need that ground.
Contrary to the previous post, most line noises are actually common mode,
including many of those caused inside the building. I only have empirical
evidence to back that up, but it comes from many trips aroud the country
investigating product failures due to line transients, and later running a
testing laboratory for compliance testing of such equipment. The worst
power I ever saw was in Sioux Falls, South Dakota; line voltages constantly
as high as 136V ac and the dirtiest stiff I ever saw. The best was Texas.

HTH
Pop`

w_tom wrote:
A house using two wire receptacles would be wired for pre-1990
earthing requirements. One need not ground wall receptacles to have
superior surge protection. But earthing at the AC mains box must be
upgraded to post 1990 code AND meet additional requirements defined in
the previous post.

This proper earthing and a 'whole house' protector are less
expensive, far more effective, AND enhances household human safety.
All this without massive rewiring of a house for three wire
receptacles. Notice a critically important parameter for surge
protection. That earthing must be short (ie 'less than 10 feet').
What is necessary to install an effective 'whole house' protector?
That household earthing must be upgraded to meet and to exceed post
1990 NEC code requirements. Superior protection regardless of two
wire or three wire receptacles.

Meanwhile, too many homes do not even have earthing that meets those
1960 earthing requirements. Too many see lights working - then assume
everything is just fine. One home even exploded because that missing
earthing (and other factors) caused electricity to conduct through the
gas meter.

Not only is 1960 earthing typically not sufficient for transistor
protection. Too often, earthing is compromised as to not provide
human protection. That earthing must both meet and 'exceed' post
1990 code requirements. To better appreciate why, learn about 'wire
impedance'. Not resistance - impedance.

Your last paragraph is good, and true. Everything else you said is suspect,
especially the gas meter comment: Gas, while IN the pipes, will not burn
and won't explode. There's a piece of that story missing if it's true.
Whole house protectors are in general good, and work well, depending.
They are not however superior to direct-connected connections. Protection
operates by shunting overvoltage currents to another source an thus
bypassing the equipment it protects. With all three wires protected, even
the ground cannot rise or fall without the other two lines doing the same.
Without it, the differences between hot or neutral and ground can be as high
as the current creates, therby trashing equipment that the ground is meant
to protect.

Now, your first paragraph indicates that whole house protection is great.
But it's only possible if the protection goes to the ground conductor, AND,
it's by no means superior to direct-connected protection with the ground
wire present.

Interesting dialogs here if nothing else.;-)


David Nebenzahl wrote:
[lotsa good stuff grounding snipped]

'Scuse me just a second, but even though the O.P. referred to their
house as having "older two-wire ungrounded wiring", that doesn't mean
that their service is *ungrounded*, only that there's not a separate
ground and neutral, correct? So their electrical service *is*
grounded (should be, anyhow).

Yes. Correct. The only caveat is that sometimes the ground isn't easily
available in the fuse or breaker box in the "old stuff".


Pop`

Pete C. wrote:
w_tom wrote:

Common mode surges are a most typical source of electronics damage.

useless bogus blather deleted

There you go again with your nonsense.

Care to explain how a common mode surge can damage a device that has
no ground connection?

A device with only two electrical connections, hot and neutral, does
not care in the least what the voltage on these lines is relative to
ground. 0 Volts and 120 Volts or 12,000 Volts and 12,120V look
*exactly* the same to the device. Unless the surge is high enough to
blow through the insulation of the devices enclosure and arc to
ground it is absolutely irrelevant to the health of the device.

Pete C.

I'm not agreeing with the previous post, but ... common mode surges are
rarely only common mode. With all the "stuff" connected to the wires there
is, IME, often an associated longitudinal imbalance in the wires that causes
the 120V relationship to shift, usually not in a 60 cycle pattern (harmonics
and sub-harmonics). If it last for long, the protection elements usually
burn out within a short time and then the voltages make it to the equipment
itself.
The old 600V tubes used on phone wires could withstand it pretty well,
but the electronic and solid state components cannot. That's also why surge
suppressors have lights on them to indicate their operational status:
Although a protector works by shorting surges away from the equipment,
eventually they will "burn out" and become an open ckt to surges. In turn,
that's why the joule ratings on a suppressor are the most important spec.
The more joules it can handle, the longer it can last through a long or a
series of surge/s.
The 600V protection afforded by phone lines, by the way, is why any
decent surge suppressor also includes connections for the phone lines to run
thru. After any serious surge conditions, there are always a plethora of
fax machines, answering machines, modems, etc. etc. being either repaired or
replaced.

Pop`

HeyBub wrote:
wrote:
I asked a local electrician about installing a whole house surge
suppressor and he said he hadn't heard of them, and I can't find a
local supplier that stocks them.

It might be the "whole house" term that's the problem. You have to watch
out for that term: Usually it means it's a replacement for a ckt breaker,
in which case that's not really "whole" house.
Also, many of them have trip voltages of 500V, which is not sufficient to
protect sensitive computer components at all, regardless of their claims.
They start out by tripping in a few nano-seconds, and that certainly helps
protect equipment, but 1. that time extends with age, and 2. if the voltage
is at 148V, it's not going to protect ANYthing! Specs and the way they're
stated vary widely, but most good equipment suppressors begin to conduct at
about 140V, reach a knee as about 150V, and then become short ckt very
quickly and solidly. You really have to be sure you're comparing apples and
oranges with these things.

Lest I be accused of saying the "whole house" protector is useless, I am
NOT!. By having a 500V trip point, they are relying on the inbuilt surge
protection in the attached equipment to be able to take the remainder of the
voltage jolt, and for the most part it works. Anything connected to the
grid in NA is protected against surges by FCC requirements for the phone
lines, but ... those are minimums, not recommended protection ranges, and
some companies really skimp to save a penny. Grid protection is usually
only afforded by the transofrmers in the equipment, or a coil here and
there. I know, our lab has tested thousands of them over the years.
Answering machines are probably the worst IME, but it definitely varies by
company. Since the new "rules" came out, the situation has improved a lot
but still is only a set of minimum requirements, not recommended
requirements.

Pop`



Here's twelve:

http://search.ebay.com/search/search...e&category 0=

Home Depot and Loews both (sometimes) carry them.

w_tom wrote:
wrote:
Hmmm. If this is the case then why are GFCI outlets allowed on
ungrounded circuits at all? It would be easy enough to manufacture a
2-wire GFCI outlet with no ground pin for retrofits, and an
ungrounded GFCI is just begging to receive a 3-prong plug. My
understanding was that purely from a safety perspective an
ungrounded GFCI outlet was as safe as a grounded one even when used
with a 3-wire device.

Do not confuse human safety requirements with other requirements.
National Electrical Code only addresses human safety issues. GFCI
with only two wires and with the label "No Equipment Ground" (or
whatever the exact wording is) does provide human safety (if an
unearthed surge does not enter the house and damage that GFCI).

Many wires do (perform) multiple functions. Again, earthing wire
must meet human safety requirements (NEC) and must exceed those
requirements to provide transistor safety.

Code permits GFCI because code only addresses human safety issues.

Good point! That sort of says it all, doesn't it?

Pop`

wrote:
We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment.

So what type of existing wiring do you have K&T? BX? Romex no ground?

may be possible to easily add ground thruout your home if say its BX?

Pop` spake thus:

David Nebenzahl wrote:

[lotsa good stuff grounding snipped]

'Scuse me just a second, but even though the O.P. referred to their
house as having "older two-wire ungrounded wiring", that doesn't mean
that their service is *ungrounded*, only that there's not a separate
ground and neutral, correct? So their electrical service *is*
grounded (should be, anyhow).

Yes. Correct. The only caveat is that sometimes the ground isn't easily
available in the fuse or breaker box in the "old stuff".

What do you mean, not "easily available"? If present, the ground will be
connected to the neutral side, correct? Therefore easily available, no?


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

w_tom wrote:

The usual bull**** from w_ on plug-in surge suppressors.

The best information I have seen on surges and surge protection is at
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf
- the title is "How to protect your house and its contents from
lightning: IEEE guide for surge protection of equipment connected to AC
power and communication circuits" published by the IEEE in 2005 (the
IEEE is the dominant organization of electrical and electronic engineers
in the US). (This link originally came from w_.)

A second god source is:
http://www.nist.gov/public_affairs/p.../surgesfnl.pdf
- this is the "NIST recommended practice guide: Surges Happen!: how to
protect the appliances in your home" published by the National
Institute of Standards and Technology (the US government agency formerly
called the National Bureau of Standards) in 2001

Both guides were intended for wide distribution to the general public to
explain surges and how to protect against them. The IEEE guide was
targeted at people who have some (not much) technical background.

Common mode surges are a most typical source of electronics damage.
Common mode surges (H & N lift away from G) coming in on the power line
are converted to transverse mode surges (H lifts away from N & G) by the
N-G bond in US services.

Point of use (plug-in) protector would do what already exists inside
appliances. Appliance protection is typically so superior that a
surge, incapable of damaging that appliance, can still cause a plug-in
protector to smoke. This undersized (smoking) protector gets the naive
to promote more sales of a so profitable and ineffective product.
Undersized is a "straw man". Plug-in protectors come in ratings from
junk to very high.

Both the IEEE guide and NIST guide recognize plug-in suppresors as
effective.


Take a $3 power strip. Add some $0.10 parts. Sell it for $20 or
$120 as a plug-in protector. Do anything possible to avoid discussing
THE most critical component in every protection 'system': earth ground.
Amazing how word association (surge protector = surge protection)
replaces science to promote myths.
Amazing how religious beliefs about earth ground promote myths. The IEEE
guide clearly describes plug-in surge protectors as primarily CLAMPING
the voltage on all conductors to the common ground at the surge
suppressor. The clamped voltage is safe for connected equipment.
Earthing is secondary.


Appreciate further problems with plug-in protectors even 20+ years
after UL1449 was created (because this happened so often). Would you
put these on a rug or on a desk full of papers?
When you don't have technical arguments try pathetic scare tactics.

http://www.westwhitelandfire.com/Art...Protectors.pdf
Includes guidelines for using plug-in suppressors

http://www.hanford.gov/rl/?page=556&parent=554
Those with minimal reading ability can read this link talks about ”some
older model” power strips and specifically references the revised UL
standard, effective 1998, that requires a thermal disconnect as a fix
for overheating MOVs.

http://www.zerosurge.com/HTML/movs.html
This link is for ZeroSurge, and is to push their plug-in suppressor
technology using series mode protection, which w_ says doesn't work.

http://www.nmsu.edu/~safety/programs...tectorfire.htm
Same event as the first link above with pictures that don't work.

None of these links say the damaged suppressor had a UL label. None of
them say plug-in suppressors are not effective or that they should not
be used or that there is a problem under the current UL standard.
Problem fixed in 1998.


Earthing is the most essential component in every protector system.
The religious mantra again. Not shared by the IEEE of NIST.

Industry professionals, your telco, AC electric companies, commercial
radio and TV broadcasters, ham radio operators, and even Ben Franklin
demonstrated this all so necessary 'system' component. Do they install
plug-in protectors? Of course not. No earth ground means no effective
protection.
Religious mantra #3. And the NIST and IEEE say plug-in suppressors are
effective.


Yes, lack of grounding will not defeat point of use suppressers
because those grossly overpriced protectors don't even claim to protect
from a typically destructive transient. But then don't take my word
for it. Where does it list each type of transient with numbers to
define protection?
Note "each type". Common mode surges do not come in past the N-G bond in
the service. Plug-in suppressors have clamps from H-N, H-G, N-G and
handle all modes anyway. And w_ has never provided specs for "each type
of transient" for any of his favorite suppressors. Yet another stupid
argument.


How to quickly identify an ineffective protector: 1) No dedicated
earthing wire. 2) Manufacturer avoids all discussion about earthing.
Religious mantra #4.

Bottom line - the IEEE and NIST recognize plug-in suppressors as effective.

--
bud--

David Nebenzahl wrote:
Pop` spake thus:

David Nebenzahl wrote:

[lotsa good stuff grounding snipped]

'Scuse me just a second, but even though the O.P. referred to their
house as having "older two-wire ungrounded wiring", that doesn't
mean that their service is *ungrounded*, only that there's not a
separate ground and neutral, correct? So their electrical service
*is* grounded (should be, anyhow).

Yes. Correct. The only caveat is that sometimes the ground isn't
easily available in the fuse or breaker box in the "old stuff".

What do you mean, not "easily available"? If present, the ground will
be connected to the neutral side, correct? Therefore easily
available, no?

That's what I'd have thought, too. Around here, including the farm I grew
up as a teen on, the ground only actually goes to the meter. Then there's a
heavy bare wire from the meter to the fusebox, and it's lugged to the
fusebox on the back side of the box; not even visible to the naked eye. I
only found it because I pulled the meter (which you could do in those days,
NOT now!). The two boxes were connected with that heavy strap.

Our CEO sorry, code enforcement officer, grew up in the business, and he
told me once that's pretty common in a lot of areas. So, I figured it was
worth mentioning here. Guess I should have pointed it out as more of an
unusual thing; sorry.

Pop` wrote:

wrote:

We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make it
as safe as possible for people and equipment. I've already put in
GFCI outlets in bathrooms, kitchen, garage, outdoor locations. So
from a people safety perspective I think that's about as good as we
can do, and grounding would not improve that situation.

Now for equipment, I'm thinking about a panel-based whole house surge
suppressor, since the lack of grounding will defeat any point-of-use
surge suppressors. There seem to be quite a few units available with
similar specs: clamping voltages in the 400-500V range, energy
dissipation on the order of 1000 joules, maximum current 50,000 amps,
5 ns response. One example is the Intermatic 1G1240R. These seem to
generally be described as sufficient for protecting appliances but the
vendors still recommend point-of-use surge suppressors for electronic
equipment.

There is also a product sold by Tytewadd, which clamps at 130V,
maximum current 10,000 amps, and 1.5 ns response. It is specifically
advertised as protection for "sensitive equipment". But... it has a
total energy dissipation of only 70 joules, far far less than the
previous class of units.

Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician to
rewire a couple outlets in key locations, and stick with power strip
surge suppressors?

-- Dave


130V ac is too low a voltage for a clamp; line voltages can go to 132Vac for
short periods of time and be "in spec". Are you sure you read that right?
Sounds more like someting for a lab environ or such. Anyway, since you're
talking suppressors and not conditioners, that's too low a voltage rating
for everyday use 24/7; you'll spend all your time wondering why it's
alerting.
Equipment can withstand perhaps 800V. Selecting too low a clamp voltage
results in the suppressor clamping more surges than is required to
protect equipment. Clamping a surge results in power dissipated in MOVs
(the primary protection element), and MOVs deteriorate and can
eventually fail as cumulative dissipation goes up. In addition, low
clamp voltage can cause rapid failure if there is utility overvoltage.
The author of the NIST guide on surges says that overvoltage is the most
frequent cause of failure of surge protectors.

A major reason manufacturers have low clamp voltage ratings on their
surge suppressors is that it "sounds better". Higher voltages provide
better overall protection.


Joules are the important number; the higher the better. 70 joules is next
to useless for a whole-house arrangement. I'm surprised the numbers don't
go higher than 1,000 too, but haven't fiddled in that market for some time.
Joules are a measure of the total power it can consume while "protecting"
the house, so get as high as you can.

The IEEE guide on surges at:
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf
says Joule rating is not reliable for _comparison_ because there is no
standard for how the rating is determined, and comparisons are thus
apples and oranges. The guide recommends current ratings, IIRC, and has
guidelines on adequate ratings.

But energy ratings are still important. MOVs deteriorate with surge
hits. With a higher Joule rating a suppressor can withstand larger hits.
And the total cumulative energy rating of a MOV will be much higher than
the stated energy rating if the stated energy rating is much higher that
the single event hits. Higher energy ratings do not just raise the
simple sum of energy hits that can be absorbed.


Also very important is a single point ground - the phone, CATV, ...
protector earthing wire connecting with a short wire to the earthing
conductor from the panel, close to the panel. Surge currents on the
earthing wires can produce large voltage drops which can appear between
power and phone wires. Single point ground minimizes the difference
between power and phone (CATV, ...) wires.

--
bud--

On Dec 16, 9:34 am, " wrote:
wrote:

So what type of existing wiring do you have K&T? BX? Romex no ground?

may be possible to easily add ground thruout your home if say its BX?

I'm not sure of the terminology but the wiring appears to be two-wire,
and not metal-clad.

I had the original 50-year-old service panel upgraded and a new ground
rod installed. The cable and phone service is (now) properly grounded
at the same point.

I think my current plan is to order a panel mounted protector like the
Intermatic one, then try to have one outlet per room grounded, for
point-of-use suppressors. Does that seem reasonable?

-- Dave

Bud-- wrote:
Pop` wrote:

wrote:

We're moving into a house that has older two-wire ungrounded wiring.
Short of the expense of rewiring the entire house, I'd like to make
it as safe as possible for people and equipment. I've already put
in GFCI outlets in bathrooms, kitchen, garage, outdoor locations. So
from a people safety perspective I think that's about as good as
we can do, and grounding would not improve that situation.

Now for equipment, I'm thinking about a panel-based whole house
surge suppressor, since the lack of grounding will defeat any
point-of-use surge suppressors. There seem to be quite a few units
available with similar specs: clamping voltages in the 400-500V
range, energy dissipation on the order of 1000 joules, maximum
current 50,000 amps, 5 ns response. One example is the Intermatic
1G1240R. These seem to generally be described as sufficient for
protecting appliances but the vendors still recommend point-of-use
surge suppressors for electronic equipment.

There is also a product sold by Tytewadd, which clamps at 130V,
maximum current 10,000 amps, and 1.5 ns response. It is
specifically advertised as protection for "sensitive equipment". But...
it has a total energy dissipation of only 70 joules, far far
less than the previous class of units.

Does anyone have experience with the Tytewadd devices? They're not
that cheap -- $150. I'm in a generally low-lightning-risk location
(Northern California, bay area) so maybe this kind of moderate
protection is sufficient. But 70 joules is less than the specs on a
rinky dink power strip. Should I save my money, ask an electrician
to rewire a couple outlets in key locations, and stick with power
strip surge suppressors?

-- Dave


130V ac is too low a voltage for a clamp; line voltages can go to
132Vac for short periods of time and be "in spec".

Right numbers, wrong interpretation. The actual "knee" is at 135V and it's
"knee", not clamped voltage. There's a big difference. Perhaps I mispoke,
but I don't see it. The knee moves upward as the energy in the surge hits
it.

Are you sure you
read that right? Sounds more like someting for a lab environ or
such. Anyway, since you're talking suppressors and not
conditioners, that's too low a voltage rating for everyday use 24/7;
you'll spend all your time wondering why it's alerting.
Equipment can withstand perhaps 800V.

No, that's patently false unless you include energy durations along with it.
Playing withg such numbers, equipment can, by current safety

Selecting too low a clamp
voltage results in the suppressor clamping more surges than is
required to protect equipment. Clamping a surge results in power
dissipated in MOVs (the primary protection element), and MOVs
deteriorate and can eventually fail as cumulative dissipation goes
up. In addition, low clamp voltage can cause rapid failure if there
is utility overvoltage. The author of the NIST guide on surges says
that overvoltage is the most frequent cause of failure of surge
protectors.
A major reason manufacturers have low clamp voltage ratings on their
surge suppressors is that it "sounds better". Higher voltages provide
better overall protection.


Joules are the important number; the higher the better. 70 joules
is next to useless for a whole-house arrangement. I'm surprised the
numbers don't go higher than 1,000 too, but haven't fiddled in that
market for some time. Joules are a measure of the total power it can
consume while "protecting" the house, so get as high as you can.

The IEEE guide on surges at:
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf
says Joule rating is not reliable for _comparison_ because there is no
standard for how the rating is determined, and comparisons are thus
apples and oranges. The guide recommends current ratings, IIRC, and
has guidelines on adequate ratings.

But energy ratings are still important. MOVs deteriorate with surge
hits. With a higher Joule rating a suppressor can withstand larger
hits. And the total cumulative energy rating of a MOV will be much
higher than the stated energy rating if the stated energy rating is
much higher that the single event hits. Higher energy ratings do not
just raise the simple sum of energy hits that can be absorbed.


Also very important is a single point ground - the phone, CATV, ...
protector earthing wire connecting with a short wire to the earthing
conductor from the panel, close to the panel. Surge currents on the
earthing wires can produce large voltage drops which can appear
between power and phone wires. Single point ground minimizes the
difference between power and phone (CATV, ...) wires.

Bud-- wrote:
Pop` wrote:

Typing with my palms again there; ignore my preceding post.


wrote:

We're moving into a house that has older two-wire ungrounded wiring.
....

There is also a product sold by Tytewadd, which clamps at 130V,
maximum current 10,000 amps, and 1.5 ns response. It is
specifically advertised as protection for "sensitive equipment". But...
it has a total energy dissipation of only 70 joules, far far
less than the previous class of units.

If one can find the info anywhere, this is actually intended to be used in
conjunction with other equipment, which makes the 70 joules a min, not best,
but usable, energy limit.



....
Equipment can withstand perhaps 800V. Selecting too low a clamp
voltage results in the suppressor clamping more surges than is
required to protect equipment.

Of course, but you're neglecting the time/power curve of current as it
reaches and passes the "knee" of the conduction cycle.

Clamping a surge results in power
dissipated in MOVs (the primary protection element), and MOVs
deteriorate and can eventually fail as cumulative dissipation goes
up.

True, but what you're missing is that, nowdays, even the varistor ckts, and
all the solid state ckts, also include a fusing arrangement that completely
opens the ckt. In good equipment, changing the fuse is all that's required.
Cheaper equipment may not allow for the fuse to be changed, but, the fuse
"fixes" the old problem of the MOVs if you insist, going bad without knowing
it.

In addition, low clamp voltage can cause rapid failure if there
is utility overvoltage.

No, not in a properly designed protection ckt. In a misdesign, yes, but few
of those exist on the market due to UL/CSA/EC/NOMs, etc.. If you don't meet
their specs, you don't sell it (or aren't supposed to be able tog).

The author of the NIST guide on surges says
that overvoltage is the most frequent cause of failure of surge
protectors.

1. MOVs are for the cheapie units, and do actually a pretty fair job of
protection. There is some accuracy in your statement, but ... 800V (peaks =
800 x 2.828) is going to be pretty disastrous to most equipment that sees
it. It looks like you're missing the point of application points for this
equipment.
2. Your complaint about 130V clamping voltage is incorrect. The "knee" of
the operating impedance waveform initiates at 130V. It begins passing
measurable current, usually still in milliamps, at about 150V. That will
NOT burn out the varistors and other solid state devices used. Actually,
varistors have given way to better components these days but are still used
in some designs, especially inside the protected equipments.
As the energy content passes the "knee" voltage, current pass increases
exponentially until it is essentially a short circuit.


A major reason manufacturers have low clamp voltage ratings on their
surge suppressors is that it "sounds better". Higher voltages provide
better overall protection.

No, it's because it's good design these days, and/or the not so often
mentioned idea is to sacrifice the protector rather than the protected
equipment. Such vague terms as you are using are misleading and
misinformation at best.


Joules are the important number; the higher the better. 70 joules
is next to useless for a whole-house arrangement. I'm surprised the
numbers don't go higher than 1,000 too, but haven't fiddled in that
market for some time. Joules are a measure of the total power it can
consume while "protecting" the house, so get as high as you can.

The IEEE guide on surges at:
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf
says Joule rating is not reliable for _comparison_ because there is no
standard for how the rating is determined, and comparisons are thus
apples and oranges. The guide recommends current ratings, IIRC, and
has guidelines on adequate ratings.

The above is not what the IEEE guide says; you need to go read it again. It
points out the misuse of the term, and possible problems with it, but does
not recommend current ratings; it recommends well beyond just the current
ratings. When you read such documents, you have to take the entire document
into consideration, not just the paragraphs that seem to support your own
stance, because there is often a lot more to it than the one paragraph.

But energy ratings are still important. MOVs deteriorate with surge
hits.

Yes, that's true. Also time is extremely important. As is total energy.
The unfortunate part of all this is that such information as in the IEEE
goes well beyond the use of typical lay people; it's not targetted at, nor
meant for, them. When the discussions go in this direction, the layperson
is left out completely.

With a higher Joule rating a suppressor can withstand larger
hits. And the total cumulative energy rating of a MOV will be much
higher than the stated energy rating

No, it would be much LESS!! It becomes less effective also under such
circumstances. This is one of the main reasons fusing technology came into
being for surge protection. A fuse has its own time/heat/melt/etc ratings
which works in conjunction with the specs on the device doing the energy
detouring.

if the stated energy rating is
much higher that the single event hits. Higher energy ratings do not
just raise the simple sum of energy hits that can be absorbed.

I don't know what the rest of that means.


Also very important is a single point ground - the phone, CATV, ...
protector earthing wire connecting with a short wire to the earthing
conductor from the panel, close to the panel. Surge currents on the
earthing wires can produce large voltage drops which can appear
between power and phone wires.

No, the difference in potentials is between the ground references for the
stated systems, not all the wires. All grounds are not equal.

Single point ground minimizes the
difference between power and phone (CATV, ...) wires.

Not sure what that's about; guess you're still reading the IEEE specs maybe.

I'm not trying to fly in your face here; simply to keep things straight and
nothing more. I'm about out of time now so you can say pretty much what
you'd like.

If your'e interested in some good links on grounding techniques with respect
to sensitive equipment, let me know and I can look a few of them up for you.
IEEE is pretty good, and so are some of the folks who interpret it, but
there are some better links for the layperson that will make things easier
to understand. I'd simply have to relocate them again; I don't see them in
my Favorites - damn that last rebuildG.

Regards,

Pop`

wrote in message
ups.com...
Charles Schuler wrote:

Whole-house surge suppression is a good idea and that is based on
personal
experience.

130 volt clamp is too low. 70 joules is too low.

There was no Internet when I installed my first unit and I went to the
best
electrical supply house in my vicinity and talked to those folks. Now,
you
can Google this to death.

I think I can safely say I've googled it to death already. I couldn't
find any information on the Tytewadd device except from the
manufacturer. Why is a low voltage clamp bad? I'd think that it would
be better to clamp as low as possible.

I think you are mixing up the clamp voltage with maximum continuous voltage:

Typically, the maximum continuous operating voltage is 130 and the UL 1449
surge rating is 400 V.

I recommend this:
http://www.nist.gov/public_affairs/p.../surgesfnl.pdf

Good document; thanks for posting it.

Pop`


Charles Schuler wrote:
wrote in message
ups.com...
Charles Schuler wrote:

Whole-house surge suppression is a good idea and that is based on
personal
experience.

130 volt clamp is too low. 70 joules is too low.

There was no Internet when I installed my first unit and I went to
the best
electrical supply house in my vicinity and talked to those folks. Now,
you
can Google this to death.

I think I can safely say I've googled it to death already. I
couldn't find any information on the Tytewadd device except from the
manufacturer. Why is a low voltage clamp bad? I'd think that it
would be better to clamp as low as possible.

I think you are mixing up the clamp voltage with maximum continuous
voltage:
Typically, the maximum continuous operating voltage is 130 and the UL
1449 surge rating is 400 V.

I recommend this:
http://www.nist.gov/public_affairs/p.../surgesfnl.pdf

Pop` wrote:

Pete C. wrote:
wrote:

Pete C. wrote:

Lack of grounding will not "defeat" point of use suppressers. Those
suppressers will still act to suppress differential surges on the
line between neutral and hot which are most likely to cause damage
to the connected device.

Hmmm. Some surge suppressor power strip vendors specifically say
that they offer no protection and no warranty when used in an
ungrounded outlet. Are you saying that they can shunt current
between hot and neutral in a differential surge? I thought that all
surges were shunted to ground?

-- Dave

A typical cheap suppresser has three MOVs, one hot to ground, one
neutral to ground and one hot to neutral. Obviously the hot to neutral
MOV can clamp transients that are differential across the hot and
neutral regardless of the presence of a ground connection. Suppressers
using gas discharge tubes would be similar.

If the surge is common mode, raising the voltage on both hot and
neutral and the device connected has no ground connection anywhere
like a CATV connection, then the entire device will jump to the
higher potential which should cause no damage. The hot-neutral
suppresser would still attempt to clamp any excess imbalance so the
device should not see any effective over voltage unless the surge
exceeds the suppressers clamping capacity.

As for warranty, certainly the suppresser can't work to it's full
design capacity without a ground so they don't want to warranty
anything. That doesn't mean that the suppresser will be useless
without a ground.

Pete C.

True, but if you want any common-mode protection type event in particular,
which is what happens with lightning or any other signals that hits both
wires "out there", then you need that ground.
Contrary to the previous post, most line noises are actually common mode,
including many of those caused inside the building. I only have empirical
evidence to back that up, but it comes from many trips aroud the country
investigating product failures due to line transients, and later running a
testing laboratory for compliance testing of such equipment. The worst
power I ever saw was in Sioux Falls, South Dakota; line voltages constantly
as high as 136V ac and the dirtiest stiff I ever saw. The best was Texas.

HTH
Pop`

I'm in Texas. I haven't scoped the line, but power here seems to be
decent. I did have one incident last year where when walking past my
server rack in the garage I noticed the UPS beeping. Clearly the power
wasn't out so I went to investigate. The UPS reported 136V on the line
and was on battery for overvoltage protect. I got my Fluke 87 and
checked at an outlet and confirmed 135.6V (the UPS only does 3 digit). I
called TXU and the CSR had no clue what I was talking about but promised
to pass it to a tech. A few min later I got a call back from a tech and
told him what I had found. Less than 10 min later the tech was parked in
my driveway. By the time I got out to the truck he had confirmed the
high voltage and was on the radio to another tech heading to the
regulator bank a mile or so away. A few minutes later I had a nice 127V.
No problems since. I was pretty impressed with TXU's response.

Pete C.

Pop` wrote:

Pete C. wrote:
w_tom wrote:

Common mode surges are a most typical source of electronics damage.

useless bogus blather deleted

There you go again with your nonsense.

Care to explain how a common mode surge can damage a device that has
no ground connection?

A device with only two electrical connections, hot and neutral, does
not care in the least what the voltage on these lines is relative to
ground. 0 Volts and 120 Volts or 12,000 Volts and 12,120V look
*exactly* the same to the device. Unless the surge is high enough to
blow through the insulation of the devices enclosure and arc to
ground it is absolutely irrelevant to the health of the device.

Pete C.

I'm not agreeing with the previous post, but ... common mode surges are
rarely only common mode. With all the "stuff" connected to the wires there
is, IME, often an associated longitudinal imbalance in the wires that causes
the 120V relationship to shift, usually not in a 60 cycle pattern (harmonics
and sub-harmonics). If it last for long, the protection elements usually
burn out within a short time and then the voltages make it to the equipment
itself.
The old 600V tubes used on phone wires could withstand it pretty well,
but the electronic and solid state components cannot. That's also why surge
suppressors have lights on them to indicate their operational status:
Although a protector works by shorting surges away from the equipment,
eventually they will "burn out" and become an open ckt to surges. In turn,
that's why the joule ratings on a suppressor are the most important spec.
The more joules it can handle, the longer it can last through a long or a
series of surge/s.
The 600V protection afforded by phone lines, by the way, is why any
decent surge suppressor also includes connections for the phone lines to run
thru. After any serious surge conditions, there are always a plethora of
fax machines, answering machines, modems, etc. etc. being either repaired or
replaced.

Pop`

Clearly a big enough and long enough duration surge i.e. nearby
lightning hit has a good chance of exceeding the capabilities of any
reasonably affordable protection device. My point though was that the
inexpensive suppressers do still provide some protection even if they
don't have a ground and that a true common mode surge of modest
amplitude will have no effect on a device that has no ground connection.

Pete C.

Pop` wrote:


Prolog:
François Martzloff was the surge guru at the NIST (still thought of by
some of us old people as the National Bureau of Standards). He did
research and wrote many peer-reviewed papers, many of them available
(along with papers from others) at an anthology he maintains at:
http://www.eeel.nist.gov/817/pubs/spd-anthology/

One of them is:
http://www.eeel.nist.gov/817/pubs/sp...shoot%20PQ.pdf
which is a guide for phone service reps for co-op power utilities. It is
considerably more technical than the IEEE guide, and has a lot of
information on surges caused by powerline switching - may be of interest
to a few people.

He also wrote the NIST guide to surges and surge protection at:
http://www.nist.gov/public_affairs/p.../surgesfnl.pdf
which is aimed at the general public. This is the same link as Charles
Schuler provided.

...

Equipment can withstand perhaps 800V. Selecting too low a clamp
voltage results in the suppressor clamping more surges than is
required to protect equipment.

Of course, but you're neglecting the time/power curve of current as it
reaches and passes the "knee" of the conduction cycle.

Clamping a surge results in power
dissipated in MOVs (the primary protection element), and MOVs
deteriorate and can eventually fail as cumulative dissipation goes
up.

True, but what you're missing is that, nowdays, even the varistor ckts, and
all the solid state ckts, also include a fusing arrangement that completely
opens the ckt. In good equipment, changing the fuse is all that's required.
Cheaper equipment may not allow for the fuse to be changed, but, the fuse
"fixes" the old problem of the MOVs if you insist, going bad without knowing
it.

I did not comment on MOVs going “bad without knowing”.
If a MOV goes bad, changing the fuse won’t help - the new fuse will blow
too. The MOV is now low resistance.
I presume you are not saying a fuse will protect a MOV from failure from
cumulative dissipation - the MOV is already fatally damaged.

In addition, low clamp voltage can cause rapid failure if there
is utility overvoltage.

No, not in a properly designed protection ckt. In a misdesign, yes, but few
of those exist on the market due to UL/CSA/EC/NOMs, etc.. If you don't meet
their specs, you don't sell it (or aren't supposed to be able tog).

From the Martzloff co-op paper cited at the top - pdf-page 20:
“In Fact, the major cause of TVSS failures is a temporary overvoltage,
rather than an unusually large surge.”

The author of the NIST guide on surges says
that overvoltage is the most frequent cause of failure of surge
protectors.

1. MOVs are for the cheapie units, and do actually a pretty fair job of
protection. There is some accuracy in your statement, but ... 800V (peaks =
800 x 2.828) is going to be pretty disastrous to most equipment that sees
it. It looks like you're missing the point of application points for this
equipment.
2.8x gives the peak-to-peak voltage which is of no use.
800V is the peak voltage, not the RMS. Equipment fails on the peak and
lightning surges are more like a pulse making peak appropriate. 800V
withstand came from an old PC magazine evaluation on plug-in surge arrester.

From a Martzloff technical paper - pdf-page 20:
http://www.eeel.nist.gov/817/pubs/sp...es/Enduser.pdf
“The fact of the matter is that nowadays, most electronic appliances
have an inherent immunity level of at least 600 V to 800 V, so that the
clamping voltages of 330 V widely offered by TVSS manufacturers are
really not necessary. Objective assessment of the situation leads to the
conclusion that the 330 V clamping level, promoted by a few
manufacturers, was encouraged by the promulgation of UL Std 1449,
showing that voltage as the lowest in a series of possible clamping
voltages for 120 V circuits. Thus was created the downward auction of
"lower is better" notwithstanding the objections raised by several
researchers [B8] and well-informed manufacturers. One of the
consequences of this downward auction can be premature ageing of TVSS
that are called upon to carry surge currents as the result of relatively
low transient voltages that would not put equipment in jeopardy.”

2. Your complaint about 130V clamping voltage is incorrect. The "knee" of
the operating impedance waveform initiates at 130V. It begins passing
measurable current, usually still in milliamps, at about 150V. That will
NOT burn out the varistors and other solid state devices used. Actually,
varistors have given way to better components these days but are still used
in some designs, especially inside the protected equipments.
As the energy content passes the "knee" voltage, current pass increases
exponentially until it is essentially a short circuit.

I didn’t talk about a 130V [RMS] clamping voltage. I am not talking
about 130V, but overvoltage which is significantly over the normal line
voltage that puts lower UL voltage classes of MOVs above the “knee”.

I have not seen anything that indicates MOVs aren’t the dominant element
that actually provides surge protection for power circuits. From the
IEEE guide [published 2005] - guide-page 37:
“The vast majority (90%) of both hard-wired and plug-in protectors use
MOVs to perform the voltage–limiting function. In most AC protectors,
they are the only significant voltage limiters.”


A major reason manufacturers have low clamp voltage ratings on their
surge suppressors is that it "sounds better". Higher voltages provide
better overall protection.


No, it's because it's good design these days, and/or the not so often
mentioned idea is to sacrifice the protector rather than the protected
equipment. Such vague terms as you are using are misleading and
misinformation at best.

Repeating from the Enduser.pdf paper above:
“Objective assessment of the situation leads to the conclusion that the
330 V clamping level, promoted by a few manufacturers, was encouraged by
the promulgation of UL Std 1449, showing that voltage as the lowest in a
series of possible clamping voltages for 120 V circuits. Thus was
created the downward auction of "lower is better" notwithstanding the
objections raised by several researchers [B8] and well-informed
manufacturers.”


The IEEE guide on surges at:
http://www.mikeholt.com/files/PDF/Li...ion_May051.pdf
says Joule rating is not reliable for _comparison_ because there is no
standard for how the rating is determined, and comparisons are thus
apples and oranges. The guide recommends current ratings, IIRC, and
has guidelines on adequate ratings.

The above is not what the IEEE guide says; you need to go read it again. It
points out the misuse of the term, and possible problems with it, but does
not recommend current ratings; it recommends well beyond just the current
ratings. When you read such documents, you have to take the entire document
into consideration, not just the paragraphs that seem to support your own
stance, because there is often a lot more to it than the one paragraph.

I read it - all of it.
The IEEE guide gives guidance on values for service panel current and
clamp-voltage ratings on guide-pages 18-19. It gives guidance on plug-in
protector clamp-voltage ratings and discusses UL test currents
guide-page 37-38. It gives warnings on using Joule ratings pages 25 and
40. It gives no Joule ratings. I have provided more endorsement of Joule
ratings than the IEEE guide.

But energy ratings are still important. MOVs deteriorate with surge
hits.

Yes, that's true. Also time is extremely important. As is total energy.
The unfortunate part of all this is that such information as in the IEEE
goes well beyond the use of typical lay people; it's not targetted at, nor
meant for, them. When the discussions go in this direction, the layperson
is left out completely.

The IEEE guide is targeted at people ”with some technical background”
and is well within the capabilities of many here, but I usually include
a link to the NIST guide (provided above and by Charles) which is aimed
at the unwashed masses.


With a higher Joule rating a suppressor can withstand larger
hits. And the total cumulative energy rating of a MOV will be much
higher than the stated energy rating

No, it would be much LESS!! It becomes less effective also under such
circumstances. This is one of the main reasons fusing technology came into
being for surge protection. A fuse has its own time/heat/melt/etc ratings
which works in conjunction with the specs on the device doing the energy
detouring.

I suspect I am reading you wrong. Fuses aren't of use on lightning
induced surges. A fast fuse can open in 1/4 cycle, about 4ms. Surges
from lightning are over in 20-100 microseconds. If a fuse opened that
fast it would have to survive the thousands of amps of surge current and
the thousands of volts that would develop across the fuse.

if the stated energy rating is
much higher that the single event hits. Higher energy ratings do not
just raise the simple sum of energy hits that can be absorbed.

I don't know what the rest of that means.

The idea is hard to convey in just a few words. Let me try again in
excessive gory detail.
MOVs have a MCOV voltage rating (maximum continuous operating voltage)
which is the voltage at which the MOVs conduct 1mA (you referred to
above). When a MOV clamps the voltage across it, it has a current
through it and a voltage across it, which means it absorbs energy. Thus
MOVs also have an energy (Joule) rating. If the MOV takes a single hit
that is equal to its Joule rating, the MCOV will be lowered by 10%. This
is considered the end of life. As it is used further the MCOV will
continue to lower and eventually it will conduct at normal circuit
voltages resulting in thermal runaway and high current failure. Surge
protectors have thermal protectors or fuses to disconnect in this
situation.

Values taken from an actual 330Joule MOV:
* with 330J hits the MOV can withstand 1 hit - cumulative energy
dissipated 330Joules
* with 90J hits the MOV can withstand 10 hits - cumulative energy
dissipation 900Joules
* with 24J hits the MOV can withstand 100 hits – cumulative energy
dissipation 2400Joules
* with 13.5J hits the MOV can withstand 1000 hits - cumulative energy
dissipation 13,500Joules.

Note the cumulative energy rising as the energy of the hits goes down.

The point I was trying to make is that if you get a surge protector that
is rated far above the energy it is likely to dissipate in a single
event, it will be able to take far more hits (and last far longer) than
the simple sum of the hits would predict. ‘Oversizing’ the Joule rating
has definite advantages.




Also very important is a single point ground - the phone, CATV, ...
protector earthing wire connecting with a short wire to the earthing
conductor from the panel, close to the panel. Surge currents on the
earthing wires can produce large voltage drops which can appear
between power and phone wires.

No, the difference in potentials is between the ground references for the
stated systems, not all the wires. All grounds are not equal.

If the ground reference for the CATV shifts away from the ground
reference for power, that voltage will appear at anything connected to
both. An example is in the IEEE guide starting guide-page 30 where a
CATV ground block is distant from the N-G bond at the power service by
30 feet. A 3000A surge on the CATV lead-in produces a voltage difference
of 10,000V between the CATV ground block and the power system N-G. That
voltage appears at TVs connected to power and CATV, and they won’t like it.

With a “single point ground” the CATV ground block is located adjacent
to the power service and connected with a short wire to the power
earthing conductor at the power service. If the resistance to earth is a
low 5 ohms and the same 3000A surge, the power and CATV grounds will
lift from ‘absolute earth’ by 15,000V. But because of the “single point
ground”, the CATV ground and power system grounds will be together,
protecting connected equipment. “Single point ground” is one of the most
important surge protection tools. [In the previous case above, the power
ground will lift 15,000V above ‘absolute ground’ and the CATV will lift
25,00V.]

Single point ground minimizes th
difference between power and phone (CATV, ...) wires.

Not sure what that's about; guess you're still reading the IEEE specs maybe.

I'm not trying to fly in your face here; simply to keep things straight and
nothing more. I'm about out of time now so you can say pretty much what
you'd like.

If your'e interested in some good links on grounding techniques with respect
to sensitive equipment, let me know and I can look a few of them up for you.
IEEE is pretty good, and so are some of the folks who interpret it, but
there are some better links for the layperson that will make things easier
to understand. I'd simply have to relocate them again; I don't see them in
my Favorites - damn that last rebuildG.

Always interested in surge info. Technical papers are good. If you are
looking for ways to kill an evening, week, ... the anthology at the top
has numerous papers on surges.

--
bud--

Pete C. wrote:
w_tom wrote:

Common mode surges are a most typical source of electronics damage.

useless bogus blather deleted

There you go again with your nonsense.

Care to explain how a common mode surge can damage a device that has no
ground connection?

The same way a person that has no ground connection can plug his finger
into the hot and not the neutral or ground contact in a socket and still
get electrocuted. When you say the device has no ground connection, what
you really mean is that it has no *obvious* ground connection.

And even if your device is a hundred million ohms from ground, it may be
insulated from ground by something that will punch through when a 5,000
volt common-mode surge hits the device.

--
Asking Iran and Syria to help us succeed in Iraq is like your local fire
department asking a couple of arsonists to help put out the fire.
-- Joe Lieberman

w_tom wrote:
http://www.westwhitelandfire.com/Art...Protectors.pdf

Why do they suggest not daisy-chaining suppressor power strips?

--
Asking Iran and Syria to help us succeed in Iraq is like your local fire
department asking a couple of arsonists to help put out the fire.
-- Joe Lieberman

clifto wrote:

Pete C. wrote:
w_tom wrote:

Common mode surges are a most typical source of electronics damage.

useless bogus blather deleted

There you go again with your nonsense.

Care to explain how a common mode surge can damage a device that has no
ground connection?

The same way a person that has no ground connection can plug his finger
into the hot and not the neutral or ground contact in a socket and still
get electrocuted. When you say the device has no ground connection, what
you really mean is that it has no *obvious* ground connection.

And even if your device is a hundred million ohms from ground, it may be
insulated from ground by something that will punch through when a 5,000
volt common-mode surge hits the device.

--
Asking Iran and Syria to help us succeed in Iraq is like your local fire
department asking a couple of arsonists to help put out the fire.
-- Joe Lieberman

I already covered that in another reply. A device with no ground will be
unaffected by a common mode surge up to the point of insulation
breakdown through for example, the plastic case of the device, the wood
table it's on, the carpeting under the table, etc. Basically a very
close lightning strike which no affordable protection device will be
able to protect against.

Pete C.

Static electric charges can build across shoes. Touch something such
as a door or electronics. How does a circuit conduct electricity from
finger to charges beneath those shoes? Many parts in that circuit are
not conductive? But at those higher voltages, things not considered
conduct become conductive.

Yes, an appliance without a better connection to earth will be less
susceptible to damage. This is why some things are damaged whereas
others are not. Even wall paint may become a conductor at these
voltages. It is not possible to isolate an appliance from destructive
transients. Otherwise lightning could not conduct through the best
insulator - 3 miles of air.

Why does lightning strike a wooden church steeple? Wood is not a
conductor? That is your reasoning. But wood is both a conductor and a
connection to earth. Concrete is not a conductor according to your
reasoning. But concrete is such a good conductor as to be recommended
- Ufer ground.

Protection has always been about earthing transients so that
destructive paths are not found through appliances or through wooden
church steeples.

You are assuming things not conductive when a building is chock full
of conductive paths to earth. Just another reason why every high
reliability building earths before transients enter a building. They
know better. A transient permitted to electronics can find surprise
paths to earth. Best protection which is also less expensive and easy
to implement has always been to earth before a transient can enter a
building. One properly earthed 'whole house' protector is that
effective.

We are not protecting from close lightning strikes. Protection
already inside appliances makes that irrelevant. We are protecting
against a direct strike to AC mains down the strike which is a direct
strike to every household appliance. Only some appliances
destructively earth that direct strike. Which ones? You do not know.
But that answer is irrelevant if the direct strike is earthed before it
enters a building. Some utilities are earthed directly (cable TV and
satellite dish). Others require a 'whole house' protector (AC electric
and telephone). But that protection will only be as good as a single
point earth ground.

Again, this was both a problem and solution well understood way back
in the early 1900s. The technology so effective that your telco
installed it on every phone line. Why would a telephone operator in a
wooden room become a path to earth via non-conductive headphones and a
wooden chair? Those become conductive paths to earth through her body.
Why did that telephone operator not remove her headset when
thunderstorms approached? Even long before WWII, single point earthing
was well proven protection. The need for earthing has been that well
understood for that long. Otherwise lightning could find a path to
earth through that operator. If Pete C's reasoning was correct, the
operator was never at risk. Telcos knew better. Even those
non-conductive headphone and wooden chair could become a conductive and
harmful path to earth.

Protection is about earthing before transients can enter a building.
One 'whole house' protector is defined by the quality of its earthing.

Pete C. wrote:
I already covered that in another reply. A device with no ground will be
unaffected by a common mode surge up to the point of insulation
breakdown through for example, the plastic case of the device, the wood
table it's on, the carpeting under the table, etc. Basically a very
close lightning strike which no affordable protection device will be
able to protect against.

clifto wrote:
w_tom wrote:
http://www.westwhitelandfire.com/Art...Protectors.pdf

Why do they suggest not daisy-chaining suppressor power strips?

Will a power strip protector somehow stops or block what three miles
of sky could not? That is not what a power strip protector does. And
yet that is why some daisy chain power strip protectors on a myth that
more will create a chain of protection - stop or block a surge.

Meanwhile, every power strip must have a 15 amp circuit breaker so
that excessive load does not concentrate on one power strip. Fires
have killed because power strips were daisy chained when, instead, the
solution was sufficient number of wall receptacles. Fire code in some
larger cities did not permit power strips - same reason. Safer than a
$25 surge protector power strip is the $3 power strip with an essential
15 amp circuit breaker. That circuit breaker to eliminate danger of
too many loads on one wall plug. But you must confirm that breaker
exists.

That breaker is not your primary safety device. Primary protection
is to not daisy chain power strips. That breaker is only a secondary
layer of protection. If you must daisy chain power strips, then the
room needs more wall receptacles.

w_tom wrote:
clifto wrote:
w_tom wrote:
http://www.westwhitelandfire.com/Art...Protectors.pdf

Why do they suggest not daisy-chaining suppressor power strips?

Will a power strip protector somehow stops or block what three miles
of sky could not?

Yes.

That is not what a power strip protector does. And
yet that is why some daisy chain power strip protectors on a myth that
more will create a chain of protection - stop or block a surge.

Not all myth, but your'e blatherskiting so no sense wasting words on you.


Meanwhile, every power strip must have a 15 amp circuit breaker so
that excessive load does not concentrate on one power strip.

No. They do not have to be 15 amps. Ckt brkrs are not the only means
either.

Fires
have killed because power strips were daisy chained when, instead, the
solution was sufficient number of wall receptacles.

BS. You can not cite even a single instance of that claim. Do you even
know what "daisy chained" means?

Fire code in some
larger cities did not permit power strips - same reason.

No, definitely not the same reason.

Safer than a
$25 surge protector power strip is the $3 power strip with an
essential 15 amp circuit breaker.

Safer how? To what? Whom?

That circuit breaker to eliminate
danger of too many loads on one wall plug. But you must confirm that
breaker exists.

That breaker is not your primary safety device.

I havent' heard anyone claim that it was.

Primary protection
is to not daisy chain power strips.

Again, no one claimed that was the case.

That breaker is only a secondary
layer of protection. If you must daisy chain power strips, then the
room needs more wall receptacles.

You're making this up as you go along, I think.

Pete C. wrote:
clifto wrote:

Pete C. wrote:
w_tom wrote:

Common mode surges are a most typical source of electronics damage.

useless bogus blather deleted

There you go again with your nonsense.

Care to explain how a common mode surge can damage a device that
has no ground connection?

The same way a person that has no ground connection can plug his
finger into the hot and not the neutral or ground contact in a
socket and still get electrocuted. When you say the device has no
ground connection, what you really mean is that it has no *obvious*
ground connection.

And even if your device is a hundred million ohms from ground, it
may be insulated from ground by something that will punch through
when a 5,000 volt common-mode surge hits the device.

--
Asking Iran and Syria to help us succeed in Iraq is like your local
fire department asking a couple of arsonists to help put out the
fire. -- Joe Lieberman

I already covered that in another reply. A device with no ground will
be unaffected by a common mode surge up to the point of insulation
breakdown through for example, the plastic case of the device, the
wood table it's on, the carpeting under the table, etc. Basically a
very close lightning strike which no affordable protection device
will be able to protect against.

Pete C.

Actually, switch gaps usually get jumped first.