Had a potential fire hazard occur a few days ago when a plug for an electric baseboard heater (the outlet is behind some furniture) apparently developed a bad connection. Perhaps the plug was not seated properly or was dislodged by a tug on the cord? Anyway at some point things got hot. Two smoke alarms failed to go off and in the morning I was told by a family member that "the heater isn't working and apparently has fried itself."

There was a heavy smell that something had fried. Upon inspection the outlet and heater plug was fried and there was a burnt spot on the back of the furniture. The white wire insulation inside the outlet was totally crunchy, so there was considerable heat at the connection and the heat conducted up the white wire.

I guess an AFCI breaker might have shut this down, and I see one company sells temperature sensing outlets. I wish the outlets were more commonly available. The breakers would never fit my old box.

On 2/16/2014 1:27 PM, Davej wrote:
Had a potential fire hazard occur a few days ago when a plug for an
electric baseboard heater (the outlet is behind some furniture)
apparently developed a bad connection. Perhaps the plug was not seated
properly or was dislodged by a tug on the cord? ...

You were well past a "potential" hazard at that point.

More likely there was a loose connection on the outlet...isn't the
"backstabbed" type by any chance't?

That sounds like a very risky installation/usage pattern, anyway, of
placing an electric heater behind furniture...

--

On Sun, 16 Feb 2014 13:46:31 -0600, dpb wrote:

On 2/16/2014 1:27 PM, Davej wrote:
Had a potential fire hazard occur a few days ago when a plug for an
electric baseboard heater (the outlet is behind some furniture)
apparently developed a bad connection. Perhaps the plug was not seated
properly or was dislodged by a tug on the cord? ...

You were well past a "potential" hazard at that point.

Yes indeed. Congratulations Davej. You dodged a bullet


More likely there was a loose connection on the outlet...isn't the
"backstabbed" type by any chance't?

That sounds like a very risky installation/usage pattern, anyway, of
placing an electric heater behind furniture...

I think only the plug and cord were behind the sofa.

When I had this problem, it wasn't behind furniture, but I was sleeping.

I also had a very old receptacle. Mine was covered by 20 layers of
paint, but in the case of Davej, if it was more than 10 years old, maybe
he should have replaced the receptacle before using it for this,
certainly if it was at all loose or more than 15. I presume you've
replaced it now. Make sure it grips it firmly and after the heater
has been running for 20 minutes, hold the plug in your hand to see if
it is warm. It shouldn't be at all warm.

I've also seen clamps to hold a plug into a recept. Held on by the
screw in the center. Or you can make one

On 2/16/2014 2:46 PM, dpb wrote:
On 2/16/2014 1:27 PM, Davej wrote:
Had a potential fire hazard occur a few days ago when a plug for an
electric baseboard heater (the outlet is behind some furniture)
apparently developed a bad connection. Perhaps the plug was not seated
properly or was dislodged by a tug on the cord? ...

You were well past a "potential" hazard at that point.

More likely there was a loose connection on the outlet...isn't the
"backstabbed" type by any chance't?

That sounds like a very risky installation/usage pattern, anyway, of
placing an electric heater behind furniture...

--

I read the OUTLET was behind furniture. The heater,
not clear.

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On Sunday, February 16, 2014 3:58:50 PM UTC-6, Stormin Mormon wrote:
On 2/16/2014 2:46 PM, dpb wrote:
On 2/16/2014 1:27 PM, Davej wrote:
Had a potential fire hazard occur a few days ago when a plug for
an electric baseboard heater (the outlet is behind some furniture)
apparently developed a bad connection. Perhaps the plug was not
seated properly or was dislodged by a tug on the cord? ...

You were well past a "potential" hazard at that point.

More likely there was a loose connection on the outlet...isn't the
"backstabbed" type by any chance't?

That sounds like a very risky installation/usage pattern, anyway, of
placing an electric heater behind furniture...

I read the OUTLET was behind furniture. The heater,
not clear.


The outlet was old, perhaps 20+ years, but not coated with paint. The outlet is behind furniture but the heater isn't. The cord is not in a place where it would normally be touched or tugged. I remember unplugging the heater last Spring but I believe a family member plugged it back in this Fall, and that I suspect may have been the problem. Perhaps they did not plug it in carefully and fully? I never use the "backstab" holes in outlets because I don't feel they provide a reliable connection. I think I will be installing a dedicated outlet for this heater in the near future. Thanks for the comments.

On 2/16/2014 11:16 PM, Davej wrote:


The outlet was old, perhaps 20+ years, but not
coated with paint. The outlet is behind furniture
but the heater isn't. The cord is not in a place
where it would normally be touched or tugged. I
remember unplugging the heater last Spring but I
believe a family member plugged it back in this
Fall, and that I suspect may have been the problem.
Perhaps they did not plug it in carefully and fully?
I never use the "backstab" holes in outlets because
I don't feel they provide a reliable connection. I
think I will be installing a dedicated outlet for
this heater in the near future. Thanks for the
comments.


I'm pleased the outlet did not catch fire, and you
and your family are safe. Might be a good socket to
install a two dollar socket, not the bargain basket
59 center. Cheaper than rebuilding.

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On 2/16/2014 1:27 PM, Davej wrote:
Had a potential fire hazard occur a few days ago when a plug for an electric
baseboard heater (the outlet is behind some furniture) apparently developed
a bad connection. Perhaps the plug was not seated properly or was dislodged
by a tug on the cord? Anyway at some point things got hot.

Two smoke alarms failed to go off and in the morning I was told by a family
member that "the heater isn't working and apparently has fried itself."

The smell produced by overheating was probably not smoke. Not exactly
reassuring, but if there had been an actual fire the smoke alarms should
have gone off.


There was a heavy smell that something had fried. Upon inspection the outlet
and heater plug was fried and there was a burnt spot on the back of the
furniture. The white wire insulation inside the outlet was totally crunchy,
so there was considerable heat at the connection and the heat conducted up the white wire.

I guess an AFCI breaker might have shut this down, and I see one company sells
temperature sensing outlets.

There can be a loose connection that produces a "glowing connection"
that is stable, and an AFCI won't trip on arc detection because there is
no arc.

In 2001 UL did testing for Cutler-Hammer on glowing connections. Steel
connection screws (plated)were the easiest to create a glowing
connection. A few amps could produce a glowing connection. The heat can,
obviously, start fires. And the heat can carbonize the plastic, which
can create a leakage path to a ground terminal or the yoke. Since AFCIs
also have a ground fault detector (at 30 mA), that can cause an AFCI
trip. Of 16 receptacle trials, 9 tripped the AFCI. (In 6 the wire burned
open, and in 1 the test was ended after 35 hours.) A glowing connection
might also eventually become an arc.

The earliest AFCIs would only detect high current arcs - between wires.
They would not detect a loose connection, which is lower current than
the circuit breaker rating. More sensitive AFCIs were required in the
2002 NEC, and they can detect a series arc (?above 5 amps). The older
ones will still trip on a ground fault.

I wish the outlets were more commonly available. The breakers would never
fit my old box.

As gfretwell wrote, AFCI receptacles are now available. In addition to
installing them as in his post, you could put AFCI receptacles next to
the panel and use the wire-through feature to protect existing circuits.

"bud--" wrote in message news:53025e07$0$47887$c3e8da3

stuff snipped

As gfretwell wrote, AFCI receptacles are now available. In addition to
installing them as in his post, you could put AFCI receptacles next to
the panel and use the wire-through feature to protect existing circuits.

I wired in three new 20A circuits to service two space heaters and a
convection combo oven. Since I knew where the first outlets were on the
branch circuits I simply replaced those outlets with Leviton AFTR2-W
SmartlockPro Outlet Branch Circuit Arc-Fault Circuit Interrupter
Receptacle, 20-Amp units ($25 each at Amazon) and connected the downstream
outlets through the load connections.

The only real downside of doing that is that when an AFCI outlet trips, you
have to roam around the house looking for it. I've made an addendum to the
ever-growing list of notations inside the panel door of where they are
(along with GFCI's wired the same way) but it still complicates things.

There are circuits I'd like to protect where I don't necessarily know where
the first outlet in the chain happens to be (is there a way to determine
that?) so they would have to be protected by AFCI breakers instead of AFCI
outlets.

The circuit breaker AFCI's are almost twice as expensive and require a
neutral pigtail connection in the circuit breaker panel. Since my neutral
bar is already at capacity, the outlets seemed to make more sense cost-wise
and installation-wise.

I have a question for you. Is it "code" to use two neutral buss bars in a
circuit breaker panel? The one I just bought is rated for putting two 12
gauge wires under one screw but I don't like to do that if I can avoid it.
I could remove the old one and replace it with the one rated for two wires
per terminal and double up all the neutrals but I would rather install a
second one on the opposite side of the panel and still connect one wire per
terminal. Just not sure that two separate neutral buss bars is permissible.

I have to admit since reading about what you wrote about the UL tests I am
not sure arc fault protection devices are worth all the effort. I've had
two meltdowns already from plugs that were either not fully plugged in or
had come loose and one because an six-outlet adapter's crimped internal buss
bar worked itself loose. It would be nice to know if the AFCI could have
detected any of those events. I am beginning to think they might not have.

--
Bobby G.

On 2/18/2014 1:57 PM, Robert Green wrote:
"bud--" wrote in message news:53025e07$0$47887$c3e8da3

stuff snipped

As gfretwell wrote, AFCI receptacles are now available. In addition to
installing them as in his post, you could put AFCI receptacles next to
the panel and use the wire-through feature to protect existing circuits.

I wired in three new 20A circuits to service two space heaters and a
convection combo oven. Since I knew where the first outlets were on the
branch circuits I simply replaced those outlets with Leviton AFTR2-W
SmartlockPro Outlet Branch Circuit Arc-Fault Circuit Interrupter
Receptacle, 20-Amp units ($25 each at Amazon) and connected the downstream
outlets through the load connections.

New in the 2011 NEC - if you extend an existing circuit in an area where
AFCI protection is required the extension (including wiring) must be
AFCI protected. Wiring through an AFCI receptacle (as you did) is one
way to provide that protection. Almost every receptacle in a dwelling
must now be AFCI or GFCI protected (when originally wired or replaced).
In the 2014 NEC some must be both.

Also new in 2011
- replacement receptacles in areas where AFCI protection is now required
have to be AFCI protected (several methods)
- replacement receptacles in areas that now require tamper-resistant
receptacles must be tamper-resistant (that is most of the general
purpose receptacles in a dwelling)(keeps kids from putting paper-clips
in the receptacle)
- replacement receptacles in areas that now require weather-resistant
receptacles must be weather-resistant (damp locations, like outdoors)

And replacement receptacles where GFCI protection is now required must
be GFCI protected

AFCI or GFCI receptacles may have to be tamper-resistant or
weather-resistant.


The only real downside of doing that is that when an AFCI outlet trips, you
have to roam around the house looking for it. I've made an addendum to the
ever-growing list of notations inside the panel door of where they are
(along with GFCI's wired the same way) but it still complicates things.

There are circuits I'd like to protect where I don't necessarily know where
the first outlet in the chain happens to be (is there a way to determine
that?) so they would have to be protected by AFCI breakers instead of AFCI
outlets.

Or install AFCI receptacles at the panel as in my last post.


The circuit breaker AFCI's are almost twice as expensive and require a
neutral pigtail connection in the circuit breaker panel. Since my neutral
bar is already at capacity, the outlets seemed to make more sense cost-wise
and installation-wise.

I have a question for you. Is it "code" to use two neutral buss bars in a
circuit breaker panel? The one I just bought is rated for putting two 12
gauge wires under one screw but I don't like to do that if I can avoid it.
I could remove the old one and replace it with the one rated for two wires
per terminal and double up all the neutrals but I would rather install a
second one on the opposite side of the panel and still connect one wire per
terminal. Just not sure that two separate neutral buss bars is permissible.

You can double-up wires only when the manufacturer says it is allowed.
Look at the label for the panel. Neutrals are never allowed to be
doubled-up - it is a code violation (408.41).

It is relatively easy to add ground bars. The label for the panel should
say what accessory bars can be used. If you have ground wires on the
existing neutral bar they can be moved to the ground bar (and maybe
doubled-up). Neutrals can not be landed on a ground bar (the enclosure
can not be used as the neutral-path connection from ground bar to
neutral bar in a service panel).

I don't know if accessory neutral bars are available. They are not as
easy to install. Other than in a service panel, they have to be
insulated from the enclosure, and you have to figure out the size of the
conductor to connect it to the existing neutral bar.


I have to admit since reading about what you wrote about the UL tests I am
not sure arc fault protection devices are worth all the effort. I've had
two meltdowns already from plugs that were either not fully plugged in or
had come loose and one because an six-outlet adapter's crimped internal buss
bar worked itself loose. It would be nice to know if the AFCI could have
detected any of those events. I am beginning to think they might not have.

Was it a high resistance or arc? Some loose connections are an arc. In
the research done for Cutler-Hammer about 1/2 of the high resistance
connections resulted in a ground fault trip when leakage to ground
resulted from the heat. The 30 mA ground fault trip in an AFCI is there
for that reason. And a "glowing connection" may turn into an arc.

The NEC keeps increasing the locations where AFCI protection is
required. Would be nice if there was data that showed they have a major
effect. But they will likely be most useful as the wiring ages.

"bud--" wrote in message
eb.com...
On 2/18/2014 1:57 PM, Robert Green wrote:

good stuff about new 2011 requirements snipped to be moved to a new thread
later


The only real downside of doing that is that when an AFCI outlet trips,
you
have to roam around the house looking for it. I've made an addendum to
the
ever-growing list of notations inside the panel door of where they are
(along with GFCI's wired the same way) but it still complicates things.

There are circuits I'd like to protect where I don't necessarily know
where
the first outlet in the chain happens to be (is there a way to determine
that?) so they would have to be protected by AFCI breakers instead of
AFCI
outlets.

Or install AFCI receptacles at the panel as in my last post.

There's really not room for that in my panel area. I suppose I could
eventually figure out where the first outlet in a branch circuit is with a
fox and hound. I could ID all the outlets in circuit that way (or by
breaker switching) and then disconnecting the outlet that's the most likely
candidate and testing for power at the downstream outlets but that's a lot
of work and a lot of torquing around of old, cloth covered wiring that is
old and doesn't like to be bothered much anymore. Just like me. (-:

stuff snipped

The circuit breaker AFCI's are almost twice as expensive and require a
I have a question for you. Is it "code" to use two neutral buss bars in
a
circuit breaker panel? The one I just bought is rated for putting two
12
gauge wires under one screw but I don't like to do that if I can avoid
it.
I could remove the old one and replace it with the one rated for two
wires
per terminal and double up all the neutrals but I would rather install a
second one on the opposite side of the panel and still connect one wire
per
terminal. Just not sure that two separate neutral buss bars is
permissible.

You can double-up wires only when the manufacturer says it is allowed.
Look at the label for the panel. Neutrals are never allowed to be
doubled-up - it is a code violation (408.41).

Which clearly makes what I have ground bars.

It is relatively easy to add ground bars. The label for the panel should
say what accessory bars can be used. If you have ground wires on the
existing neutral bar they can be moved to the ground bar (and maybe
doubled-up). Neutrals can not be landed on a ground bar (the enclosure
can not be used as the neutral-path connection from ground bar to
neutral bar in a service panel).

I was under the impression, probably wrong, that if you connected a
secondary buss bar with a large gauge wire (#8) to the neutral buss bar that
it was acceptable to land neutral wires on the secondary buss bar but now I
am not sure where I read that or if it's true. I realize now that the OEM
neutral bar on my Square D panel sits above all the breakers and looks to be
isolated from the enclosure.

I just looked and it seems that the small buss bar I have can be
piggy-backed to the existing neutral bar, but I am going to have to look up
the manual for the panel to be sure. Now a number of things have become
clearer to me, which is probably good safety wise but is going to mean a lot
of work and/or expense to bring it up to code.

Electrically the panel is connected to the neutral conductor just because
ground wires are connected to the neutral bus, correct? I think you're
saying that the issue is that a secondary neutral buss can't depend on that
connection. The Square D panel has mounts for ground buss bars on both
sides of the panel. Even moving all the ground wires from the original
neutral buss to a auxiliary ground bar won't help because there aren't many
grounds (this is a two-pin outlet house, at least on all the older
circuits).

I installed a number of dual skinnies just to be able to take high current
outlet loads off the old circuits which now primarily serve low wattage CFL
lights. I also installed one AFCI breaker with a pigtail before moving on to
the cheaper AFCI outlets, in part because of the lack of neutral buss bar
connections.

I don't know if accessory neutral bars are available. They are not as
easy to install. Other than in a service panel, they have to be
insulated from the enclosure, and you have to figure out the size of the
conductor to connect it to the existing neutral bar.

I am not sure what you mean by "other than in a service panel, they have to
be insulated from the enclosure." I thought I did this correctly because I
recall going out and having to buy one foot of 8 gauge wire to connect the
secondary bar going alongside the rows of breakers inside the circuit
breaker panel. I'll have to review my notes about that. I did notice
Square D make two identical forms of the buss bar except one was tinted
green, the other was all silver which made me also believe that they could
be used to ":land neutrals" (I like that phrase) as well as grounds.

I have to admit since reading about what you wrote about the UL tests I
am
not sure arc fault protection devices are worth all the effort. I've
had
two meltdowns already from plugs that were either not fully plugged in
or
had come loose and one because an six-outlet adapter's crimped internal
buss
bar worked itself loose. It would be nice to know if the AFCI could
have
detected any of those events. I am beginning to think they might not
have.

Was it a high resistance or arc?

One was an arc because you could hear it. The others were most likely high
resistance.

Some loose connections are an arc. In
the research done for Cutler-Hammer about 1/2 of the high resistance
connections resulted in a ground fault trip when leakage to ground
resulted from the heat. The 30 mA ground fault trip in an AFCI is there
for that reason. And a "glowing connection" may turn into an arc.

Someone mentioned thermally protected outlets that cut out when they get too
hot. I've never heard of them. Are they something standard in the
industry? Would they offer protection against high resistance connections
that the AFCI's don't seem to provide?

The NEC keeps increasing the locations where AFCI protection is
required. Would be nice if there was data that showed they have a major
effect. But they will likely be most useful as the wiring ages.

I suppose that the data will fill in over time. Based on the number of
breaker trips I've experienced in my life, I suspect that breakers have
saved my life a lot more often than most other protection devices including
my firearms. (-:

Thanks for your input, Bud.

--
Bobby G.

On 2/20/2014 8:23 PM, Robert Green wrote:
"bud--" wrote in message
eb.com...
On 2/18/2014 1:57 PM, Robert Green wrote:

good stuff about new 2011 requirements snipped to be moved to a new thread
later


The only real downside of doing that is that when an AFCI outlet trips,
you
have to roam around the house looking for it. I've made an addendum to
the
ever-growing list of notations inside the panel door of where they are
(along with GFCI's wired the same way) but it still complicates things.

There are circuits I'd like to protect where I don't necessarily know
where
the first outlet in the chain happens to be (is there a way to determine
that?) so they would have to be protected by AFCI breakers instead of
AFCI
outlets.

Or install AFCI receptacles at the panel as in my last post.

There's really not room for that in my panel area. I suppose I could
eventually figure out where the first outlet in a branch circuit is with a
fox and hound. I could ID all the outlets in circuit that way (or by
breaker switching) and then disconnecting the outlet that's the most likely
candidate and testing for power at the downstream outlets but that's a lot
of work and a lot of torquing around of old, cloth covered wiring that is
old and doesn't like to be bothered much anymore. Just like me. (-:

Making a map with device locations and circuit number is real useful,
but a PITA. Would give you an idea where the first device is.

If you AFCI the first receptacle and wire through the rest, the device
protects the wiring downstream. All the load is at or downstream. The
AFCI receptacle will protect the wiring back to the panel from series
arcs (loose connections) by disconnecting the load that maintains the arc.


stuff snipped

The circuit breaker AFCI's are almost twice as expensive and require a
I have a question for you. Is it "code" to use two neutral buss bars in
a
circuit breaker panel? The one I just bought is rated for putting two
12
gauge wires under one screw but I don't like to do that if I can avoid
it.
I could remove the old one and replace it with the one rated for two
wires
per terminal and double up all the neutrals but I would rather install a
second one on the opposite side of the panel and still connect one wire
per
terminal. Just not sure that two separate neutral buss bars is
permissible.

You can double-up wires only when the manufacturer says it is allowed.
Look at the label for the panel. Neutrals are never allowed to be
doubled-up - it is a code violation (408.41).

Which clearly makes what I have ground bars.

It is relatively easy to add ground bars. The label for the panel should
say what accessory bars can be used. If you have ground wires on the
existing neutral bar they can be moved to the ground bar (and maybe
doubled-up). Neutrals can not be landed on a ground bar (the enclosure
can not be used as the neutral-path connection from ground bar to
neutral bar in a service panel).

I was under the impression, probably wrong, that if you connected a
secondary buss bar with a large gauge wire (#8) to the neutral buss bar that
it was acceptable to land neutral wires on the secondary buss bar but now I
am not sure where I read that or if it's true. I realize now that the OEM
neutral bar on my Square D panel sits above all the breakers and looks to be
isolated from the enclosure.

I assume that if there is a wire-connection that would work. You have to
figure out what size wire is appropriate. Slight chance an inspector
might object to using something the manufacturer calls a "ground bar" as
a neutral bar.


I just looked and it seems that the small buss bar I have can be
piggy-backed to the existing neutral bar, but I am going to have to look up
the manual for the panel to be sure. Now a number of things have become
clearer to me, which is probably good safety wise but is going to mean a lot
of work and/or expense to bring it up to code.

Electrically the panel is connected to the neutral conductor just because
ground wires are connected to the neutral bus, correct? I think you're
saying that the issue is that a secondary neutral buss can't depend on that
connection. The Square D panel has mounts for ground buss bars on both
sides of the panel. Even moving all the ground wires from the original
neutral buss to a auxiliary ground bar won't help because there aren't many
grounds (this is a two-pin outlet house, at least on all the older
circuits).

I installed a number of dual skinnies just to be able to take high current
outlet loads off the old circuits which now primarily serve low wattage CFL
lights. I also installed one AFCI breaker with a pigtail before moving on to
the cheaper AFCI outlets, in part because of the lack of neutral buss bar
connections.

A subpanel near the service panel is another possibility. (But then you
will never be able to sell your house - according to one opinion. And
you won't be able to get insurance. And a house inspector may say the
house should be torn down. And it should be torn down. And that does not
include the shame of having a subpanel.)


I don't know if accessory neutral bars are available. They are not as
easy to install. Other than in a service panel, they have to be
insulated from the enclosure, and you have to figure out the size of the
conductor to connect it to the existing neutral bar.

I am not sure what you mean by "other than in a service panel, they have to
be insulated from the enclosure."

In a service panel the neutral and enclosure are connected together.
Could be a wire. Often is a screw and looks like a mounting screw but
may be green. If the neutral and enclosure are bonded, an added neutral
bar would not have to be insulated from the enclosure (but may not rely
on the enclosure as the electrical connection back to original neutral
bar).

In a subpanel, an added neutral bar must be insulated.

I thought I did this correctly because I
recall going out and having to buy one foot of 8 gauge wire to connect the
secondary bar going alongside the rows of breakers inside the circuit
breaker panel. I'll have to review my notes about that. I did notice
Square D make two identical forms of the buss bar except one was tinted
green, the other was all silver which made me also believe that they could
be used to ":land neutrals" (I like that phrase) as well as grounds.

I have to admit since reading about what you wrote about the UL tests I
am
not sure arc fault protection devices are worth all the effort. I've
had
two meltdowns already from plugs that were either not fully plugged in
or
had come loose and one because an six-outlet adapter's crimped internal
buss
bar worked itself loose. It would be nice to know if the AFCI could
have
detected any of those events. I am beginning to think they might not
have.

Was it a high resistance or arc?

One was an arc because you could hear it. The others were most likely high
resistance.

Some loose connections are an arc. In
the research done for Cutler-Hammer about 1/2 of the high resistance
connections resulted in a ground fault trip when leakage to ground
resulted from the heat. The 30 mA ground fault trip in an AFCI is there
for that reason. And a "glowing connection" may turn into an arc.

Someone mentioned thermally protected outlets that cut out when they get too
hot. I've never heard of them. Are they something standard in the
industry? Would they offer protection against high resistance connections
that the AFCI's don't seem to provide?

I have never heard of thermally protected outlets. Is that feature UL
listed?

And AFCIs may trip on a ground fault caused by a "glowing connection",
or if a glowing connection turns into an arc.


The NEC keeps increasing the locations where AFCI protection is
required. Would be nice if there was data that showed they have a major
effect. But they will likely be most useful as the wiring ages.

I suppose that the data will fill in over time. Based on the number of
breaker trips I've experienced in my life, I suspect that breakers have
saved my life a lot more often than most other protection devices including
my firearms. (-:

"bud--" wrote in message news:53084114$0$59830$c3e8da3
stuff snipped

Making a map with device locations and circuit number is real useful,
but a PITA. Would give you an idea where the first device is.

If you AFCI the first receptacle and wire through the rest, the device
protects the wiring downstream. All the load is at or downstream. The
AFCI receptacle will protect the wiring back to the panel from series
arcs (loose connections) by disconnecting the load that maintains the arc.

After thinking about the for a while, I realized I could use my X-10 signal
strength meters to discover the first outlet on a branch circuit. If I
place a test transmitter on another branch, the X-10 meter will show
noticeable signal attentuation as measurements are taken at each outlet on
the branch circuit in question. I often use that technique to "zero in" on
noise generators. As you move closer to the noisemaker the noise reading
function of my XTBM meter shows an increase in the noise signal level (in
millivolts). Never thought the technique could ID the first outlet in a
circuit, but I think it will.

stuff snipped

I was under the impression, probably wrong, that if you connected a
secondary buss bar with a large gauge wire (#8) to the neutral buss bar
that
it was acceptable to land neutral wires on the secondary buss bar but
now I
am not sure where I read that or if it's true. I realize now that the
OEM
neutral bar on my Square D panel sits above all the breakers and looks
to be
isolated from the enclosure.

I assume that if there is a wire-connection that would work. You have to
figure out what size wire is appropriate. Slight chance an inspector
might object to using something the manufacturer calls a "ground bar" as
a neutral bar.

I had the panel inspected after I installed the first set of dual skinnies.
But I think at that time I had moved all the ground wires from the panel's
legit neutral bar to the ground bar. I was mostly concerned at the time
that the inspector would disallow the dual skinnies because of the potential
to overload the panel. It was obvious from what I had done, though, that I
was relieving the older cloth-wire circuits of heavy loads (like toasters)
and using the new 12/2 romex instead. The overall load on the panel wasn't
changing, just the distribution of that load. Which brings up another
subject. Today with my tong meter I realized that one side of the panel was
pulling way more amps than the other. I guess that's for another thread,
too. What happens when a circuit panel is unbalanced and has substantially
more of a load on one leg than the other?

Since the last inspection I have added more circuits but the overall load is
still way less than the total the panel is rated for. Unfortunately now the
neutrals are connected to the auxiliary buss bar and not just the ground
wires and I recall that was new work, post inspection.

A subpanel near the service panel is another possibility. (But then you
will never be able to sell your house - according to one opinion. And
you won't be able to get insurance. And a house inspector may say the
house should be torn down. And it should be torn down. And that does not
include the shame of having a subpanel.)

No subpanels for me! A long time ago I decided that this house would
probably have to be "gutted" when sold so it's not a big issue. Part of the
problem is that it was built in 1941 when there was a shortage of everything
and those shortages were reflected in the materials used in the house. No
building paper between the floors, badly cured wood on the roof, etc.
Fortunately where I live the land's what's worth the most $ and houses like
mine are often knocked down so that larger homes can be built to replace
them.

stuff snipped

I am not sure what you mean by "other than in a service panel, they have
to
be insulated from the enclosure."

In a service panel the neutral and enclosure are connected together.
Could be a wire. Often is a screw and looks like a mounting screw but
may be green. If the neutral and enclosure are bonded, an added neutral
bar would not have to be insulated from the enclosure (but may not rely
on the enclosure as the electrical connection back to original neutral
bar).

Gotcha. I may be safe after all. The question now is whether to double up
all the ground wires on the buss bar I installed (with the number 8 wire
connected to the panel's original neutral bar) or to install another ground
bar on the left side of the panel. I am leaning toward the latter because I
don't like the idea of disturbing the old wires yet again and because
there's a lot more free space on the left side.

In a subpanel, an added neutral bar must be insulated.

Another reason not to endure the shame of a subpanel.

stuff snipped

Someone mentioned thermally protected outlets that cut out when they get
too
hot. I've never heard of them. Are they something standard in the
industry? Would they offer protection against high resistance
connections
that the AFCI's don't seem to provide?

I have never heard of thermally protected outlets. Is that feature UL
listed?

Dunno. I'll first have to look up where someone mentioned them here and
then go on to Google to find out more. They have to be pretty simple to
build - just needs a klixon internally to interrupt the circuit in case of
an overheat. Look for that in a separate thread as the initial search
turned up a number of likely candidates. There's probably a third thread to
evolve from this. Is UL listing necessary for approval of the installation
of auxiliary equipment like an X-10 coupler/repeater? Now I remember why I
haven't invited the inspector back . . .

And AFCIs may trip on a ground fault caused by a "glowing connection",
or if a glowing connection turns into an arc.

A temperature "aware" outlet seems to be the solution to glowing
connections. More in a new thread.

Thanks for your input, Bud.

--
Bobby G.

On Wednesday, February 26, 2014 5:59:43 AM UTC-5, Robert Green wrote:

I had the panel inspected after I installed the first set of dual skinnies.

But I think at that time I had moved all the ground wires from the panel's

legit neutral bar to the ground bar. I was mostly concerned at the time

that the inspector would disallow the dual skinnies because of the potential

to overload the panel. It was obvious from what I had done, though, that I

was relieving the older cloth-wire circuits of heavy loads (like toasters)

and using the new 12/2 romex instead. The overall load on the panel wasn't

changing, just the distribution of that load. Which brings up another

subject. Today with my tong meter I realized that one side of the panel was

pulling way more amps than the other.


How much is way much more?


I guess that's for another thread,

too. What happens when a circuit panel is unbalanced and has substantially

more of a load on one leg than the other?



Nothing unless the neutral service conductor was undersized
when it was installed and you put such an unbalanced load on
it that it exceeded it's rating, eg managing to put close to
the full service current rating on just one leg, which is highly
unlikely with typical 120V loads.






In a subpanel, an added neutral bar must be insulated.



Another reason not to endure the shame of a subpanel.


I don't know what's shameful about using a subpanel. They
are installed frequently and properly done, nothing wrong with
them. It sure beats tearing out a perfectly good main panel
just to add two more circuits. And having the neutral not grounded
in the subpanel is trivial, they are made to do that. On the
other hand, if you have an old main panel and there are other
reasons to upgrade the whole thing, then I can see going to a new
larger panel.




stuff snipped



Someone mentioned thermally protected outlets that cut out when they get

too

hot. I've never heard of them. Are they something standard in the

industry? Would they offer protection against high resistance

connections

that the AFCI's don't seem to provide?



I have never heard of thermally protected outlets. Is that feature UL

listed?



Dunno. I'll first have to look up where someone mentioned them here and

then go on to Google to find out more. They have to be pretty simple to

build - just needs a klixon internally to interrupt the circuit in case of

an overheat. Look for that in a separate thread as the initial search

turned up a number of likely candidates. There's probably a third thread to

evolve from this. Is UL listing necessary for approval of the installation

of auxiliary equipment like an X-10 coupler/repeater? Now I remember why I

haven't invited the inspector back . . .


I think it's required to be listed and while it's typically listed
by UL it doesn't have to specifically be UL, just a recognized testing
lab. Given the crap that most X-10 products are, and since you're
worried about getting thermally protected outlets, AFCI's etc, I'd
think you'd want the X10 repeater listed. Is this an active one or
just a passive one? The passive ones, at least some, are just caps
AFAIK.

wrote in message
...
On Wednesday, February 26, 2014 5:59:43 AM UTC-5, Robert Green wrote:

Which brings up another subject. Today with my tong meter I realized
that
one side of the panel was pulling way more amps than the other.


How much is way much more?

From 11 to 15A

What happens when a circuit panel is unbalanced and has substantially
more of a load on one leg than the other?

Nothing unless the neutral service conductor was undersized
when it was installed and you put such an unbalanced load on
it that it exceeded it's rating, eg managing to put close to
the full service current rating on just one leg, which is highly
unlikely with typical 120V loads.

OK. I remember a long, long time ago I had problems with a Sony monitor at
work that an electrician attributed to an unbalanced panel, but balancing
the loads didn't solve the wavering on the monitor so while rebalancing at
that site didn't help, it probably didn't hurt, either.

Another reason not to endure the shame of a subpanel.

I don't know what's shameful about using a subpanel.

I was just "playing along" with Bud who I assumed was recapping odd comments
he's seen people make about subpanels. If I misunderstood you, Bud, I
apologize in advance.

They are installed frequently and properly done, nothing wrong with
them. It sure beats tearing out a perfectly good main panel
just to add two more circuits. And having the neutral not grounded
in the subpanel is trivial, they are made to do that. On the
other hand, if you have an old main panel and there are other
reasons to upgrade the whole thing, then I can see going to a new
larger panel.

A total rewire is probably what's required here but as I said, when we leave
this house, it will probably be gutted and renovated into a much larger
house with all new wiring. Putting in a new service panel at this late date
wouldn't be cost effective. I would probably have been forced to upgrade a
long time ago except that the advent of CFLs and LEDs really reduced the
overall load. Same with a new fridge and AC. Much lower total current draw
than the old equipment.

stuff snipped

I think it's required to be listed and while it's typically listed
by UL it doesn't have to specifically be UL, just a recognized testing
lab. Given the crap that most X-10 products are, and since you're
worried about getting thermally protected outlets, AFCI's etc, I'd
think you'd want the X10 repeater listed.

Different concerns. I'd already melted more than one outlet with a space
heater whose plug had worked slightly loose. That's a serious fire hazard.
With the XTB-II repeater, I am not worried that it will start a fire.

Is this an active one or just a passive one? The passive ones, at least
some, are just caps
AFAIK.

This is an active one designed by a guy who built custom electronics for
NASA for several decades. He looked into UL listing but it would have made
the device impracticably expensive. He's provided detailed circuit diagrams
and component lists and enough information to make me comfortable using the
device. We had extensive conversations about worst-case scenarios and while
I'd like it to be UL listed, I don't see it as being a dealbreaker,
especially considering how useful the device has been. You can see for
yourself that this is not typical Chinese made X-10 consumer stuff:

http://jvde.us/xtb/XTB-II_description.htm

Jeff's design and soldering work is impeccable and the XTB-II pretty much
eliminates all of the typical problems X-10 faces in the world of modern
switching-power supplies. Unlike other repeaters, this unit boosts the X-10
signal to over 25 volts which is usually enough to power through any
interference.

Investing in the XTB-II saved me from having to switch to another home
automation protocol and protected my substantial investment in X-10 gear. I
am sure you would change your opinion about X-10 if you saw one of these
units in action and the difference it makes to an "iffy" X-10 setup. The 5
to 10 volt signal strength of standard X-10 gear is just not enough to reach
across phases or fight signal attenuation. That's partly because modern
electronics are pretty noisy and are often designed to choke RFI which,
ironically, is what the X-10 signal looks like to many devices. A 120Khz
noise spike at the zero crossing.

--
Bobby G.

On 2/26/2014 4:59 AM, Robert Green wrote:

I was mostly concerned at the time
that the inspector would disallow the dual skinnies because of the potential
to overload the panel.

Panels will have a rating something like 10/16. There are 10 full size
breaker positions and you can put 16 "poles" in it. A tandem breaker is
2 poles, so you could install up to 6 tandem breakers. The label should
tell you the rating.

The panel is tested with the maximum number of poles - 16 above - and UL
does not allow installing more poles than that. That is done by only
allowing tandem breakers in certain positions (6 in the example above).
The label will indicate which positions tandem breakers can be installed
in. In a 10/20 panel it is all positions. It may also be no positions. A
SquareD tandem breaker has a bar on the bottom that has to fit into a
slot through the gutter rail, which exists only in the positions where
tandem breakers are allowed. These are class CTL panels and breakers
(circuit limiting) and they have been around a long time.

The inspector wants to know that tandem breakers were installed in
positions where they are allowed.

There are also non-class CTL tandem breakers that can be installed in
any position - for older panels that are before CTL came out. I know no
one here would ever install one of them in a class CTL panel.

On 2/26/2014 1:23 PM, Robert Green wrote:
wrote in message
...
On Wednesday, February 26, 2014 5:59:43 AM UTC-5, Robert Green wrote:

Which brings up another subject. Today with my tong meter I realized
that
one side of the panel was pulling way more amps than the other.


How much is way much more?

From 11 to 15A


Doesn't sound like much unless it is a 60A panel. It will vary depending
on what is on anyway


Another reason not to endure the shame of a subpanel.

I don't know what's shameful about using a subpanel.

I was just "playing along" with Bud who I assumed was recapping odd comments
he's seen people make about subpanels. If I misunderstood you, Bud, I
apologize in advance.

There is a certain party here who has that opinion of subpanels, telling
RBM he did schlocky work because he has a subpanel in his house. The
same person has strong opinions about k&t, insurance, and some other
subjects.

On Wednesday, February 26, 2014 2:23:18 PM UTC-5, Robert Green wrote:
wrote in message

...

On Wednesday, February 26, 2014 5:59:43 AM UTC-5, Robert Green wrote:



Which brings up another subject. Today with my tong meter I realized

that

one side of the panel was pulling way more amps than the other.





How much is way much more?



From 11 to 15A


Perfectly normal.





I think it's required to be listed and while it's typically listed

by UL it doesn't have to specifically be UL, just a recognized testing

lab. Given the crap that most X-10 products are, and since you're

worried about getting thermally protected outlets, AFCI's etc, I'd

think you'd want the X10 repeater listed.



Different concerns. I'd already melted more than one outlet with a space

heater whose plug had worked slightly loose. That's a serious fire hazard.

With the XTB-II repeater, I am not worried that it will start a fire.



Is this an active one or just a passive one? The passive ones, at least

some, are just caps

AFAIK.



This is an active one designed by a guy who built custom electronics for

NASA for several decades. He looked into UL listing but it would have made

the device impracticably expensive. He's provided detailed circuit diagrams

and component lists and enough information to make me comfortable using the

device. We had extensive conversations about worst-case scenarios and while

I'd like it to be UL listed, I don't see it as being a dealbreaker,

especially considering how useful the device has been. You can see for

yourself that this is not typical Chinese made X-10 consumer stuff:



http://jvde.us/xtb/XTB-II_description.htm



Jeff's design and soldering work is impeccable and the XTB-II pretty much

eliminates all of the typical problems X-10 faces in the world of modern

switching-power supplies. Unlike other repeaters, this unit boosts the X-10

signal to over 25 volts which is usually enough to power through any

interference.



Investing in the XTB-II saved me from having to switch to another home

automation protocol and protected my substantial investment in X-10 gear. I

am sure you would change your opinion about X-10 if you saw one of these

units in action and the difference it makes to an "iffy" X-10 setup. The 5

to 10 volt signal strength of standard X-10 gear is just not enough to reach

across phases or fight signal attenuation. That's partly because modern

electronics are pretty noisy and are often designed to choke RFI which,

ironically, is what the X-10 signal looks like to many devices. A 120Khz

noise spike at the zero crossing.



--

Bobby G.

I hear you, but I don't think it would change my overall opinion of X-10.
I'm sure it helps increase the reliability and can make it work where
it otherwise would not. Part of the problem is that they are not upfront
about this problem. I'm sure a lot of people wind up not being able
to get it to work because it really should have a bridge/repeater across
the phases. Then if you want such a device, they are expensive and
as you've found out, have problems of their own, ie not UL listed and
there is no guarantee that they will make it all work either. Or maybe
you get it to work for what you're currently doing, then want to add
something else and that won't work.

The other big problem is that AFAIK, no one is doing anything new
with X-10. What you have now, you've pretty much had the same stuff
for more than a decade, ie no new products, no improvements, etc.
The outdoor sensors don't last, that's another problem. I'd still
use it for a simple application, where I put $20 in it and if it works
it works, but I would not choose it as a means to more extensive home
automation.

bud-- posted for all of us...

And I know how to SNIP

I know no
one here would ever install one of them in a class CTL panel.



You are one funny guy!

--
Tekkie

"bud--" wrote in message
eb.com...
On 2/26/2014 1:23 PM, Robert Green wrote:
wrote in message
...
On Wednesday, February 26, 2014 5:59:43 AM UTC-5, Robert Green wrote:

Which brings up another subject. Today with my tong meter I realized
that
one side of the panel was pulling way more amps than the other.


How much is way much more?

From 11 to 15A


Doesn't sound like much unless it is a 60A panel. It will vary depending
on what is on anyway

Thanks. Just wasn't sure what the parameters/problems of unbalanced loads
were. Thanks to you and T4 for clearing that up.

Another reason not to endure the shame of a subpanel.

I don't know what's shameful about using a subpanel.

I was just "playing along" with Bud who I assumed was recapping odd
comments
he's seen people make about subpanels. If I misunderstood you, Bud, I
apologize in advance.

There is a certain party here who has that opinion of subpanels, telling
RBM he did schlocky work because he has a subpanel in his house. The
same person has strong opinions about k&t, insurance, and some other
subjects.

As I thought. Thanks for being circumspect about it and not mentioning
names. Things have been remarkably civil here in AHR of late. Of course,
my blocked senders list is growing like kudzu . . .

--
Bobby G.

"bud--" wrote in message
eb.com...
On 2/26/2014 4:59 AM, Robert Green wrote:

I was mostly concerned at the time
that the inspector would disallow the dual skinnies because of the
potential
to overload the panel.

Panels will have a rating something like 10/16. There are 10 full size
breaker positions and you can put 16 "poles" in it. A tandem breaker is
2 poles, so you could install up to 6 tandem breakers. The label should
tell you the rating.

Panel is a QO CAT QO BW - 20M - 100 - 5

I believe that the 20 refers to the max # of breakers and the 100 is the max
current. Otherwise the catalog number don't seem to agree with the listing
in the PDF. No idea what BW means. It's hard to read the label because
it's a) faded, b) upside down and c) obscured by neutral and ground wires.

The panel is tested with the maximum number of poles - 16 above - and UL
does not allow installing more poles than that. That is done by only
allowing tandem breakers in certain positions (6 in the example above).
The label will indicate which positions tandem breakers can be installed
in. In a 10/20 panel it is all positions. It may also be no positions. A
SquareD tandem breaker has a bar on the bottom that has to fit into a
slot through the gutter rail, which exists only in the positions where
tandem breakers are allowed. These are class CTL panels and breakers
(circuit limiting) and they have been around a long time.

This has to be a pre 1985 panel and I haven't found it yet although I found
a few like it in this PDF:

www.farnell.com/datasheets/1626663.pdf

The inspector wants to know that tandem breakers were installed in
positions where they are allowed.

From what I can see, that's not an issue with my panel. As I recall, the
hot bar (not sure of the technical name of the alternating metal "fingers"
running down the center) was the same from the top to the bottom - no
specialized slots for tandems (why would there be?). The replacement
breakers have a very different connection mechanism that the original ones.
The ones that came with the panel have two pronged clips that make the
connection to the rail but the replacements have a single claw-like
"grabber" - so different looking that I was sure I bought the wrong
breakers.

There are also non-class CTL tandem breakers that can be installed in
any position - for older panels that are before CTL came out. I know no
one here would ever install one of them in a class CTL panel.

I am pretty sure that at least on of the labels on the panel has the letters
CTL but if it came out after 1985, then I definitely don't have a CTL panel.
From what I can see of the PDF listed above, the breaker panels that support
special slots for tandems look quite different from the box I have which is
a series of alternating metal fingers running down the heavy black plastic
"spine" of the panel.

http://en.wikipedia.org/wiki/Circuit_total_limitation

Talks about CTL being in place since 1969 and replacement breakers being
non-CTL. Even if the panel ends up "dangerously overloaded" isn't the main
breaker supposed to trip before anything bad happens?

--
Bobby G.

On 3/2/2014 12:55 PM, Robert Green wrote:
"bud--" wrote in message
eb.com...
On 2/26/2014 4:59 AM, Robert Green wrote:

I was mostly concerned at the time
that the inspector would disallow the dual skinnies because of the
potential
to overload the panel.

Panels will have a rating something like 10/16. There are 10 full size
breaker positions and you can put 16 "poles" in it. A tandem breaker is
2 poles, so you could install up to 6 tandem breakers. The label should
tell you the rating.

Panel is a QO CAT QO BW - 20M - 100 - 5

I believe that the 20 refers to the max # of breakers and the 100 is the max
current. Otherwise the catalog number don't seem to agree with the listing
in the PDF. No idea what BW means. It's hard to read the label because
it's a) faded, b) upside down and c) obscured by neutral and ground wires.

I agree with 20 and 100. M means it has a main breaker. (As in your link
below.)

I don't know what BW is either. Need a real old catalog.

I would read "20" as not allowing tandem breakers. "2024" would allow
tandems in 4 positions. But it is an old catalog number.

Seems like UL had maximum number of poles depending on the panel rating.
I think a 100A panel had a max of 20 poles and 200A had a max of 40 or
42 poles. That makes it harder to overload a panel, but doesn't work so
good if you don't have much on each circuit (so you need more circuits).
SquareD has panels with a lot more poles ("circuits") than that now.


The panel is tested with the maximum number of poles - 16 above - and UL
does not allow installing more poles than that. That is done by only
allowing tandem breakers in certain positions (6 in the example above).
The label will indicate which positions tandem breakers can be installed
in. In a 10/20 panel it is all positions. It may also be no positions. A
SquareD tandem breaker has a bar on the bottom that has to fit into a
slot through the gutter rail, which exists only in the positions where
tandem breakers are allowed. These are class CTL panels and breakers
(circuit limiting) and they have been around a long time.

This has to be a pre 1985 panel and I haven't found it yet although I found
a few like it in this PDF:

www.farnell.com/datasheets/1626663.pdf

The inspector wants to know that tandem breakers were installed in
positions where they are allowed.

From what I can see, that's not an issue with my panel. As I recall, the
hot bar (not sure of the technical name of the alternating metal "fingers"
running down the center) was the same from the top to the bottom - no
specialized slots for tandems (why would there be?). The replacement
breakers have a very different connection mechanism that the original ones.
The ones that came with the panel have two pronged clips that make the
connection to the rail but the replacements have a single claw-like
"grabber" - so different looking that I was sure I bought the wrong
breakers.

SquareD class CTL tandem breakers have the usual horizontal clip at the
busbar end. At the gutter rail end they have what you describe as a
claw, which fits into a slot in the gutter rail. The slot is only
present at the positions where tandem breakers are allowed.

Your farnell link has a crappy picture for a Homeline panel on page 9 of
your link.
A better picture is
http://www.circuitbreakersuperstore...._8_2_5862.html
where the gutter rail claw can be seen.

Regular breakers just have a clip at the gutter rail end, as with your
original breakers.


There are also non-class CTL tandem breakers that can be installed in
any position - for older panels that are before CTL came out. I know no
one here would ever install one of them in a class CTL panel.

I am pretty sure that at least on of the labels on the panel has the letters
CTL but if it came out after 1985, then I definitely don't have a CTL panel.
From what I can see of the PDF listed above, the breaker panels that support
special slots for tandems look quite different from the box I have which is
a series of alternating metal fingers running down the heavy black plastic
"spine" of the panel.

The difference is only in the gutter rail.


http://en.wikipedia.org/wiki/Circuit_total_limitation

Talks about CTL being in place since 1969 and replacement breakers being
non-CTL. Even if the panel ends up "dangerously overloaded" isn't the main
breaker supposed to trip before anything bad happens?

Yes.

I don't entirely agree with the limit on circuits. If I watch the
connected load I might install tandems where you are not supposed to.

I think one reason for the limit is to limit the heat produced in the
panel. Heat can cause a breaker to trip at a lower current. Would seem
like a 100A panel would only make 100A of heat no matter how many breakers.


There is, in general, a limitation for fuses and circuit breakers of 80%
for "continuous" loads, which are loads that are on for 3 hours or more.
My understanding is this is based on panel heat, and the breaker may
trip at less than 100% if the load is on for more than 3 hours.

An exposed 20A breaker or fuse by itself is supposed to hold at 20A forever.

circuit limit number is to protect breaker box from being overfilled. just like te limit of the number of wires in any box

"bud--" wrote in message
b.com...
On 3/2/2014 12:55 PM, Robert Green wrote:
"bud--" wrote in message
eb.com...
On 2/26/2014 4:59 AM, Robert Green wrote:

I was mostly concerned at the time
that the inspector would disallow the dual skinnies because of the
potential
to overload the panel.

Panels will have a rating something like 10/16. There are 10 full size
breaker positions and you can put 16 "poles" in it. A tandem breaker is
2 poles, so you could install up to 6 tandem breakers. The label should
tell you the rating.

Panel is a QO CAT QO BW - 20M - 100 - 5

I believe that the 20 refers to the max # of breakers and the 100 is the
max
current. Otherwise the catalog number don't seem to agree with the
listing
in the PDF. No idea what BW means. It's hard to read the label because
it's a) faded, b) upside down and c) obscured by neutral and ground
wires.

I agree with 20 and 100. M means it has a main breaker. (As in your link
below.)

I don't know what BW is either. Need a real old catalog.

I've found that publications printed before the internet often never make
their way to the net. I don't see myself spending too much time looking for
the meaning of BW.

I would read "20" as not allowing tandem breakers. "2024" would allow
tandems in 4 positions. But it is an old catalog number.

Those tandem breakers fit just fine g. I looked at the box again and the
rails are continous without interruption or anything that looks like special
slotting meant to accept tandems only in one spot.

Seems like UL had maximum number of poles depending on the panel rating.
I think a 100A panel had a max of 20 poles and 200A had a max of 40 or
42 poles. That makes it harder to overload a panel, but doesn't work so
good if you don't have much on each circuit (so you need more circuits).
SquareD has panels with a lot more poles ("circuits") than that now.

It would be nice to upgrade to a newer panel but it wouldn't be cost
effective. This place has to be "shelled" when I am through with it. Boy
will my heirs be disappointed. (-:

The panel is tested with the maximum number of poles - 16 above - and
UL
does not allow installing more poles than that. That is done by only
allowing tandem breakers in certain positions (6 in the example above).
The label will indicate which positions tandem breakers can be
installed
in. In a 10/20 panel it is all positions. It may also be no positions.
A
SquareD tandem breaker has a bar on the bottom that has to fit into a
slot through the gutter rail, which exists only in the positions where
tandem breakers are allowed. These are class CTL panels and breakers
(circuit limiting) and they have been around a long time.

This has to be a pre 1985 panel and I haven't found it yet although I
found
a few like it in this PDF:

www.farnell.com/datasheets/1626663.pdf

The inspector wants to know that tandem breakers were installed in
positions where they are allowed.

From what I can see, that's not an issue with my panel. As I recall,
the
hot bar (not sure of the technical name of the alternating metal
"fingers"
running down the center) was the same from the top to the bottom - no
specialized slots for tandems (why would there be?). The replacement
breakers have a very different connection mechanism that the original
ones.
The ones that came with the panel have two pronged clips that make the
connection to the rail but the replacements have a single claw-like
"grabber" - so different looking that I was sure I bought the wrong
breakers.

SquareD class CTL tandem breakers have the usual horizontal clip at the
busbar end. At the gutter rail end they have what you describe as a
claw, which fits into a slot in the gutter rail. The slot is only
present at the positions where tandem breakers are allowed.

No slots in my gutter rail. All the same from top to bottom but at least
now I know why they changed the clamping mechanism. Boy was I certain when
I got them home that they were the wrong style breakers even though I had
religiously copied down the breaker information from the one I had pulled.
I also discovered that the previous owner had replaced 15A breakers with 20A
ones, which I based on the fact that the same gauge wires were feeding both
sizes of breaker. I replaced those 20A units with 15A ones, just to be on
the safe side.

I figured wiring from 1940 was not likely to be 20A capable but the idiots
before me apparently found the kitchen circuits tripped less frequently with
the larger capacity breaker. Sadly, you could see that the 20A breaker feed
wires had evidence of overheating. That's what led me to add the
tandem/dual skinnies and run new wires to the kitchen and workshop areas.

Your farnell link has a crappy picture for a Homeline panel on page 9 of
your link.
A better picture is
http://www.circuitbreakersuperstore...._8_2_5862.html
where the gutter rail claw can be seen.

Regular breakers just have a clip at the gutter rail end, as with your
original breakers.

Either kind of breaker fits into any slot on the breaker panel I have. I
saw a printer's mark on one label in the box that said 1961. Of course,
there's no telling if that's related to the date the panel was installed.
But based on the history of this house that I know about, it's entirely
possible the panel is that old. I know at one point it was a screw fuse
panel because I found a bunch of fuses directly below the panel area when I
pulled the old paneling off the basement.

There are also non-class CTL tandem breakers that can be installed in
any position - for older panels that are before CTL came out. I know no
one here would ever install one of them in a class CTL panel.

I am pretty sure that at least on of the labels on the panel has the
letters
CTL but if it came out after 1985, then I definitely don't have a CTL
panel.
From what I can see of the PDF listed above, the breaker panels that
support
special slots for tandems look quite different from the box I have which
is
a series of alternating metal fingers running down the heavy black
plastic
"spine" of the panel.

The difference is only in the gutter rail.

Then I don't have a CTL panel.

http://en.wikipedia.org/wiki/Circuit_total_limitation

Talks about CTL being in place since 1969 and replacement breakers being
non-CTL. Even if the panel ends up "dangerously overloaded" isn't the
main
breaker supposed to trip before anything bad happens?

Yes.

I don't entirely agree with the limit on circuits. If I watch the
connected load I might install tandems where you are not supposed to.

I think the offloading of old, cloth-covered wiring to newer 12/2 NM
justified the use of tandems in my case. It has to be safer using new
wiring than muddling through with the old crap.

I think one reason for the limit is to limit the heat produced in the
panel. Heat can cause a breaker to trip at a lower current. Would seem
like a 100A panel would only make 100A of heat no matter how many
breakers.

There are some interesting charts here about temperature, load and other
factors relating to breakers and how they trip and when.

http://static.schneider-electric.us/...CT9801R108.pdf

There is, in general, a limitation for fuses and circuit breakers of 80%
for "continuous" loads, which are loads that are on for 3 hours or more.
My understanding is this is based on panel heat, and the breaker may
trip at less than 100% if the load is on for more than 3 hours.

An exposed 20A breaker or fuse by itself is supposed to hold at 20A
forever.

I saw something (not especially credible - one of those "ask me" sorts of
sites) that said because of the heat generated by the electronics in AFCI
breakers, they had to be mounted away from each other. I also read
manufacturer info that said that heat generation was taken into account.
That's where I also saw something about the NEC required that instrument
controls that a user had to operate with fingers not be over 140F. That
seems a little high.

--
Bobby G.

"bob haller" wrote in message
...
circuit limit number is to protect breaker box from being overfilled. just
like te limit of the number of wires in any box

My panel seems to be in an oversize box - thank God - because there's at
least 8" of empty space in the box below where the gutter rails end.

--
Bobby G.

On 3/6/2014 10:57 AM, Robert Green wrote:
"bud--" wrote in message
b.com...

Those tandem breakers fit just fine g. I looked at the box again and the
rails are continous without interruption or anything that looks like special
slotting meant to accept tandems only in one spot.

Then I presume you used non-CTL tandem breakers.


The difference is only in the gutter rail.

Then I don't have a CTL panel.

You can't tell that from the rail. The panel could just not allow any
tandem breakers.

Sounds like from the date you found it is not a CTL panel and it is
kosher to use non-CTL tandem breakers.

I am not entirely convinced that is a problem anyway. If you have a
100A panel seems like you would only get '100A of heat' no matter how
many circuits/poles there are. You would have to watch how much load you
connect so you don't actually overload the panel.

"bud--" wrote in message
eb.com...
On 3/6/2014 10:57 AM, Robert Green wrote:
"bud--" wrote in message
b.com...

Those tandem breakers fit just fine g. I looked at the box again and
the
rails are continous without interruption or anything that looks like
special
slotting meant to accept tandems only in one spot.

Then I presume you used non-CTL tandem breakers.

I used what Home Depot had on the shelves that matched the QO designation
and it was approved by the AHJ. Dual skinnies/tandems are a pretty popular
item in this development of houses built to house the army of workers that
descended on DC at the beginning of WWII. Fortunately with CFLs and more
efficient motors the average load for such items has decreased substantially
(although the number of plug in chargers and appliances has increased
geometrically). I assume when I ultimately switch to LEDs the overall load
will be reduced again.

The difference is only in the gutter rail.

Then I don't have a CTL panel.

You can't tell that from the rail. The panel could just not allow any
tandem breakers.

Tell that to the four that are in there now! (-:

Sounds like from the date you found it is not a CTL panel and it is
kosher to use non-CTL tandem breakers.

That date's not conclusive. They could have been using the same label for
20 years. There must be some other date markings inside the box. Reading
all the details is getting to be like reading "War and Peace" - very
arduous.

I am not entirely convinced that is a problem anyway. If you have a
100A panel seems like you would only get '100A of heat' no matter how
many circuits/poles there are. You would have to watch how much load you
connect so you don't actually overload the panel.

I do. A long time ago I installed two Hall effect sensors on the incoming
feeds. For days I was calibrating them with various space heater loads
(this was the springtime and it drove my wife a little crazy having me run
space heaters with the windows open. She's a frugal New Englander). Those
sensors feed into my HomeVision home automation controller's analog inputs.
From there I can roughly gauge the total load at any one time and it very
rarely exceeds 50A, and only then when it's very cold which self-limits the
overheating panel problem to some extent.

--
Bobby G.