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Surfwospam
 
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Default 2-prong outlet, 3-prong power strip

I'm trying to help a neighbor set up a computer and printer that her
out-of-state son shipped to her.

My neighbor's house was build in the 1960s and only has two-prong outlets. In
the past, whenever she wanted to use a 3-prong plug device, she just used an
adapter.

I'm wondering if it would be okay to plug in the surge protector/power strip
her son sent into a 3-prong adapter and then plug that into the 2-prong wall
outlet. There would be three devices plugged into the power strip/surge
protector: a CPU, monitor, and printer.

Specifically, I want to make sure we're not risking starting an electrical fire
(or some other calamity).

If she does need to get an outlet turned into a 3-prong outlet, what elements
would the electrician take into account in his price (e.g., distance from
switch box) and what's your best guess on what that might cost?

Thanks in advance for any advice you can provide.

Surf
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Greg
 
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The first thing I would do is be sure if there is a ground present in the box.
A lot of older houses used a grounded system but installed 2 prong outlets. If
so the adapter works as long as you connect the ground tab to the center screw.
With that connected try a 3 light tester.
Better is to use a self grounding recptacle ... all assuming a ground is
actually present in the box.
If there is no ground present she really should try to get a circuit pulled in
for the PC. Surge protectors are not very good without a ground.
  #3   Report Post  
m Ransley
 
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A surge protector does not have a discharge path without a ground.

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Greg
 
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A surge protector does not have a discharge path without a ground.


Surge protectors discharge most of the surge as heat in the MOVs. You will have
no neutral to ground protection tho.


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Speedy Jim
 
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wrote:

In the time it took you to type your message, you could have replaced
the outlet with a 3 prong one. They cost about One Dollar. Just be
sure the outlet (green screw) is grounded to the box with a short
piece of green or bare wire. A home built in the 60's should have a
ground in the box. Just be sure you follow the same wiring that was
used. The black or red wires go to the BRASS colored screws, the
White wires go to the SILVER colored screws, and the green screw is
the ground. Not too dificult to do. Be sure to shut off the power
when you do the job.

Don't just bet on the box being grounded! Grounding recepts were
just being phased in during the mid 60's. And not every section
of this great land adopted grounding simultaneously. The box ground
path needs to be checked and verified before replacing any 2-prong
recept.

Jim



On 17 Nov 2004 20:36:52 GMT,
(Surfwospam) wrote:


I'm trying to help a neighbor set up a computer and printer that her
out-of-state son shipped to her.

My neighbor's house was build in the 1960s and only has two-prong outlets. In
the past, whenever she wanted to use a 3-prong plug device, she just used an
adapter.

I'm wondering if it would be okay to plug in the surge protector/power strip
her son sent into a 3-prong adapter and then plug that into the 2-prong wall
outlet. There would be three devices plugged into the power strip/surge
protector: a CPU, monitor, and printer.

Specifically, I want to make sure we're not risking starting an electrical fire
(or some other calamity).

If she does need to get an outlet turned into a 3-prong outlet, what elements
would the electrician take into account in his price (e.g., distance from
switch box) and what's your best guess on what that might cost?

Thanks in advance for any advice you can provide.

Surf



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Greg
 
Posts: n/a
Default

The real trick was having a house built to "GI Bill" or FHA standards (common
around Washington DC). Our 1951 house in Md had 3 wire Romex even though the
receptacles were 2 prong. We retrofitted them to 3 prong in the early 60s.

  #8   Report Post  
Junior Member
 
Posts: 7
Default

Quote:
Originally Posted by Speedy Jim
wrote:

In the time it took you to type your message, you could have replaced
the outlet with a 3 prong one. They cost about One Dollar. Just be
sure the outlet (green screw) is grounded to the box with a short
piece of green or bare wire. A home built in the 60's should have a
ground in the box. Just be sure you follow the same wiring that was
used. The black or red wires go to the BRASS colored screws, the
White wires go to the SILVER colored screws, and the green screw is
the ground. Not too dificult to do. Be sure to shut off the power
when you do the job.

Don't just bet on the box being grounded! Grounding recepts were
just being phased in during the mid 60's. And not every section
of this great land adopted grounding simultaneously. The box ground
path needs to be checked and verified before replacing any 2-prong
recept.

Jim



On 17 Nov 2004 20:36:52 GMT,
(Surfwospam) wrote:


I'm trying to help a neighbor set up a computer and printer that her
out-of-state son shipped to her.

My neighbor's house was build in the 1960s and only has two-prong outlets. In
the past, whenever she wanted to use a 3-prong plug device, she just used an
adapter.

I'm wondering if it would be okay to plug in the surge protector/power strip
her son sent into a 3-prong adapter and then plug that into the 2-prong wall
outlet. There would be three devices plugged into the power strip/surge
protector: a CPU, monitor, and printer.

Specifically, I want to make sure we're not risking starting an electrical fire
(or some other calamity).

If she does need to get an outlet turned into a 3-prong outlet, what elements
would the electrician take into account in his price (e.g., distance from
switch box) and what's your best guess on what that might cost?

Thanks in advance for any advice you can provide.

Surf


NEC says you can simply change rec to gfci marked as no equiptment ground
  #9   Report Post  
Dan
 
Posts: n/a
Default

On Sat, 27 Nov 2004 04:24:31 +0000, Rich123
wrote:


Speedy Jim Wrote:
wrote:
-
In the time it took you to type your message, you could have replaced
the outlet with a 3 prong one. They cost about One Dollar. Just be
sure the outlet (green screw) is grounded to the box with a short
piece of green or bare wire. A home built in the 60's should have a
ground in the box. Just be sure you follow the same wiring that was
used. The black or red wires go to the BRASS colored screws, the
White wires go to the SILVER colored screws, and the green screw is
the ground. Not too dificult to do. Be sure to shut off the power
when you do the job.
-
Don't just bet on the box being grounded! Grounding recepts were
just being phased in during the mid 60's. And not every section
of this great land adopted grounding simultaneously. The box ground
path needs to be checked and verified before replacing any 2-prong
recept.

Jim

-

On 17 Nov 2004 20:36:52 GMT,
(Surfwospam) wrote:

-
I'm trying to help a neighbor set up a computer and printer that her
out-of-state son shipped to her.

My neighbor's house was build in the 1960s and only has two-prong
outlets. In
the past, whenever she wanted to use a 3-prong plug device, she just
used an
adapter.

I'm wondering if it would be okay to plug in the surge protector/power
strip
her son sent into a 3-prong adapter and then plug that into the 2-prong
wall
outlet. There would be three devices plugged into the power
strip/surge
protector: a CPU, monitor, and printer.

Specifically, I want to make sure we're not risking starting an
electrical fire
(or some other calamity).

If she does need to get an outlet turned into a 3-prong outlet, what
elements
would the electrician take into account in his price (e.g., distance
from
switch box) and what's your best guess on what that might cost?

Thanks in advance for any advice you can provide.

Surf-

-

NEC says you can simply change rec to gfci marked as no equiptment
ground


The NEC does allow that, but a surge supressor won't function reliably
without an equipment ground. To properly protect the computer
equipment a properly grounded outlet should be installed.

Dan
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Default 2-prong outlet, 3-prong power strip

ted writes:

What a ridiculous response.


You so funny.
I'm not the Dan you replied to, but that was 16 years ago.
What a ridiculous response indeed.


You may or may not know this, but most of the posts on homeowners hub
are actually from Usenet.

On Usenet, we don't see old posts, only the most recent posts and replies.
The post you just replied to is 16 years old. Please check
the dates and if you feel you must reply, please include the
original post in your reply.

Better yet, get a Usenet account. You can do this for free.


--
Dan Espen


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Default 2-prong outlet, 3-prong power strip

On Tue, 09 Feb 2021 19:35:31 -0500, Dan Espen wrote:

ted writes:

What a ridiculous response.


You so funny.
I'm not the Dan you replied to, but that was 16 years ago.
What a ridiculous response indeed.


You may or may not know this, but most of the posts on homeowners hub
are actually from Usenet.

On Usenet, we don't see old posts, only the most recent posts and replies.


My provider keeps 4000 days worth of posts for this group, or roughly 11
years. I configure my newsreader to only show 'new' messages, but the old
stuff is there if you want it.

The post you just replied to is 16 years old. Please check
the dates and if you feel you must reply, please include the
original post in your reply.

Better yet, get a Usenet account. You can do this for free.


I agree, 16 years is a bit old in this context.

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Default 2-prong outlet, 3-prong power strip

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.

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Default 2-prong outlet, 3-prong power strip

On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.


The only way to be sure about the ground is by using a bug eye tester
with the adapter bonded to the screw or by visual inspection.
Grounding the boxes predates the universal use of 5-15 receptacles by
at least a decade tho.
My old house was built in 1954 and it had grounded boxes with 1-15
receptacles. That was using the paper covered Romex and the 16ga
grounding conductor. That smaller conductor is probably sufficient for
grounding purposes but in 68 they made it full size for 14ga-10ga
cables.
I am not sure exactly when grounding the boxes showed up in the NEC
but it had to be early 50s, late 40s.
YMMV depending on when your AHJ adopted the code.
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Default 2-prong outlet, 3-prong power strip


On Wed, 10 Feb 2021 15:53:59 -0500, posted for all of us to
digest...


On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.


The only way to be sure about the ground is by using a bug eye tester
with the adapter bonded to the screw or by visual inspection.
Grounding the boxes predates the universal use of 5-15 receptacles by
at least a decade tho.
My old house was built in 1954 and it had grounded boxes with 1-15
receptacles. That was using the paper covered Romex and the 16ga
grounding conductor. That smaller conductor is probably sufficient for
grounding purposes but in 68 they made it full size for 14ga-10ga
cables.
I am not sure exactly when grounding the boxes showed up in the NEC
but it had to be early 50s, late 40s.
YMMV depending on when your AHJ adopted the code.


What is a bug eye detector? Never heard that..

--
Tekkie
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Default 2-prong outlet, 3-prong power strip

On Wed, 10 Feb 2021 17:33:49 -0500, Tekkie©
wrote:


On Wed, 10 Feb 2021 15:53:59 -0500, posted for all of us to
digest...


On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.


The only way to be sure about the ground is by using a bug eye tester
with the adapter bonded to the screw or by visual inspection.
Grounding the boxes predates the universal use of 5-15 receptacles by
at least a decade tho.
My old house was built in 1954 and it had grounded boxes with 1-15
receptacles. That was using the paper covered Romex and the 16ga
grounding conductor. That smaller conductor is probably sufficient for
grounding purposes but in 68 they made it full size for 14ga-10ga
cables.
I am not sure exactly when grounding the boxes showed up in the NEC
but it had to be early 50s, late 40s.
YMMV depending on when your AHJ adopted the code.


What is a bug eye detector? Never heard that..


One of those 3 lamp testers


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Default 2-prong outlet, 3-prong power strip

On Wednesday, February 10, 2021 at 7:17:27 PM UTC-5, wrote:
On Wed, 10 Feb 2021 17:33:49 -0500, Tekkie©
wrote:

On Wed, 10 Feb 2021 15:53:59 -0500, posted for all of us to
digest...


On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.

The only way to be sure about the ground is by using a bug eye tester
with the adapter bonded to the screw or by visual inspection.
Grounding the boxes predates the universal use of 5-15 receptacles by
at least a decade tho.
My old house was built in 1954 and it had grounded boxes with 1-15
receptacles. That was using the paper covered Romex and the 16ga
grounding conductor. That smaller conductor is probably sufficient for
grounding purposes but in 68 they made it full size for 14ga-10ga
cables.
I am not sure exactly when grounding the boxes showed up in the NEC
but it had to be early 50s, late 40s.
YMMV depending on when your AHJ adopted the code.


What is a bug eye detector? Never heard that..

One of those 3 lamp testers


Looks like a large plug, you plug it in to a receptacle, it has three LEDs
from which you can determine if there is a ground, if the hot and neutral
are reversed, etc.

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On Thu, 11 Feb 2021 06:11:58 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 7:17:27 PM UTC-5, wrote:
On Wed, 10 Feb 2021 17:33:49 -0500, Tekkie©
wrote:

On Wed, 10 Feb 2021 15:53:59 -0500, posted for all of us to
digest...


On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.

The only way to be sure about the ground is by using a bug eye tester
with the adapter bonded to the screw or by visual inspection.
Grounding the boxes predates the universal use of 5-15 receptacles by
at least a decade tho.
My old house was built in 1954 and it had grounded boxes with 1-15
receptacles. That was using the paper covered Romex and the 16ga
grounding conductor. That smaller conductor is probably sufficient for
grounding purposes but in 68 they made it full size for 14ga-10ga
cables.
I am not sure exactly when grounding the boxes showed up in the NEC
but it had to be early 50s, late 40s.
YMMV depending on when your AHJ adopted the code.

What is a bug eye detector? Never heard that..

One of those 3 lamp testers


Looks like a large plug, you plug it in to a receptacle, it has three LEDs
from which you can determine if there is a ground, if the hot and neutral
are reversed, etc.


You just need to be careful using one on a 2 wire system. It can OK a
deadly situation. If you have a reversal of neutral and the ungrounded
conductor, then someone uses the "neutral" as the ground, the tester
will be happy but the user won't when they get electrocuted.
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On 2/10/2021 2:53 PM, wrote:
On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.


The only way to be sure about the ground is by using a bug eye tester


Those tester will probably show if the ground is good. But the tester
uses a very small current for the test, and will indicate good if there
is a high resistance in the ground path, like 100 ohms. A ground path
with 100 ohms resistance is useless. A more reliable test would be
connecting a 200W light bulb from hot to ground. I have a tester that
tests with a relatively high current pulses. I think from a previous
thread you have a similar tester.

The testers will also not catch problems that should be very rare, like
if some idiot connects the ground contact to the neutral and an idiot
has reversed hot and neutral. A non-contact voltage tester can be used
to determine if hot is actually hot and neutral and ground are not.

IMHO it is useful to know the limitations of test equipment.

with the adapter bonded to the screw or by visual inspection.
Grounding the boxes predates the universal use of 5-15 receptacles by
at least a decade tho.
My old house was built in 1954 and it had grounded boxes with 1-15
receptacles. That was using the paper covered Romex and the 16ga
grounding conductor. That smaller conductor is probably sufficient for
grounding purposes but in 68 they made it full size for 14ga-10ga
cables.
I am not sure exactly when grounding the boxes showed up in the NEC
but it had to be early 50s, late 40s.
YMMV depending on when your AHJ adopted the code.


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On Thu, 11 Feb 2021 16:58:22 -0600, bud-- wrote:

On 2/10/2021 2:53 PM, wrote:
On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.


The only way to be sure about the ground is by using a bug eye tester


Those tester will probably show if the ground is good. But the tester
uses a very small current for the test, and will indicate good if there
is a high resistance in the ground path, like 100 ohms. A ground path
with 100 ohms resistance is useless. A more reliable test would be
connecting a 200W light bulb from hot to ground. I have a tester that
tests with a relatively high current pulses. I think from a previous
thread you have a similar tester.

They do make better testers that will look for a resistance between 1
ohm and some smaller amount.
They verify a reasonable grounding impedance and will also detect a
neutral connected to the ground by the fact that the resistance is
virtually zero.
Ecos makes the one I have.
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On 2/11/2021 11:10 PM, wrote:
On Thu, 11 Feb 2021 16:58:22 -0600, bud-- wrote:

On 2/10/2021 2:53 PM,
wrote:
On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.

The only way to be sure about the ground is by using a bug eye tester


Those tester will probably show if the ground is good. But the tester
uses a very small current for the test, and will indicate good if there
is a high resistance in the ground path, like 100 ohms. A ground path
with 100 ohms resistance is useless. A more reliable test would be
connecting a 200W light bulb from hot to ground. I have a tester that
tests with a relatively high current pulses. I think from a previous
thread you have a similar tester.

They do make better testers that will look for a resistance between 1
ohm and some smaller amount.
They verify a reasonable grounding impedance and will also detect a
neutral connected to the ground by the fact that the resistance is
virtually zero.
Ecos makes the one I have.


The one I have is also an old Ecos. I haven't had it out in years.

A GFCI will trip on a N-G short downstream. It is a feature that was
added many years ago. There is a second current transformer that tries
to inject a small current on the H and N. It is only possible if there
is a N-G short (or reverse wired H-N and a H (which is now N)-G short.



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Default 2-prong outlet, 3-prong power strip

On Thursday, February 11, 2021 at 5:58:09 PM UTC-5, bud-- wrote:
On 2/10/2021 2:53 PM, wrote:
On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.


The only way to be sure about the ground is by using a bug eye tester

Those tester will probably show if the ground is good. But the tester
uses a very small current for the test, and will indicate good if there
is a high resistance in the ground path, like 100 ohms. A ground path
with 100 ohms resistance is useless. A more reliable test would be
connecting a 200W light bulb from hot to ground. I have a tester that
tests with a relatively high current pulses. I think from a previous
thread you have a similar tester.

The testers will also not catch problems that should be very rare, like
if some idiot connects the ground contact to the neutral and an idiot
has reversed hot and neutral.


The plug in testers do detect reversed hot and neutral.

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Posts: 1,058
Default 2-prong outlet, 3-prong power strip


On Wed, 10 Feb 2021 19:17:02 -0500, posted for all of us to
digest...


On Wed, 10 Feb 2021 17:33:49 -0500, Tekkie©
wrote:


On Wed, 10 Feb 2021 15:53:59 -0500,
posted for all of us to
digest...


On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.

The only way to be sure about the ground is by using a bug eye tester
with the adapter bonded to the screw or by visual inspection.
Grounding the boxes predates the universal use of 5-15 receptacles by
at least a decade tho.
My old house was built in 1954 and it had grounded boxes with 1-15
receptacles. That was using the paper covered Romex and the 16ga
grounding conductor. That smaller conductor is probably sufficient for
grounding purposes but in 68 they made it full size for 14ga-10ga
cables.
I am not sure exactly when grounding the boxes showed up in the NEC
but it had to be early 50s, late 40s.
YMMV depending on when your AHJ adopted the code.


What is a bug eye detector? Never heard that..


One of those 3 lamp testers


Gotcha

--
Tekkie
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