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GFCI *breaker* failure modes?

P

Phil Allison

Jan 1, 1970
0
"bud--"


** Lack of reply here shows this smug dude's total dishonesty.
--------------------------------------------------------------


I have seen it referred to by several people who are more technically
competent than you about GFCIs.

** More smug, pompous crap.
The pile of crap I posted, which you replied to, was:

"There is a second current transformer that tries to put a small common
mode current in both the H and N wire."


** Not seen outside the USA and not seen in all GFCIs there either.

And you failed to mention that it is not needed to produce tripping in 99%
of practical situations.

So I did.

Piss off - bulkhead.


..... Phil
 
D

Don Y

Jan 1, 1970
0
Hi Mike,

For a very long time, although incoming services must be bonded to
Earth, they cannot be relied up to provide an Earth. We also have Earth
Spikes.

You aren't supposed to rely on earth to be the "return" for the
supply. E.g., you can't use the metal frame of an all steel building
to "eliminate the need for a neutral connector" (like you would
in an automobile)

"Earth" never carries current.
That's a total no-no for us in the UK!

I also thought that many US homes and premises had their own
transformers, such that a local Neutral and Earth were inherently at the
same potential?

Businesses (high power demands) may have their own transformers, etc.
But, individual residences don't.

Here, for example, four homes will be fed off one transformer
(which is located at grade level as our utilities are below grade).

I *assume* there is an earthing conductor there (it's under a
half cubic yard/meter "box")
They are for us, but the separation of Neutral and Earth mean that under
Live-Neutral fault conditions, any fault Neutral potential doesn't find
its way to the Earth. Under normal conditions they are up to a few
volts different.

At the panel, they are equivalent. In the residence, neutral may
differ instantaneously due to IR drops in the neutral conductor.
Because no current flows through "earth", it is always *at* the
same potential as inside the electrical panel.

There are rules governing how "good" the earth must be. Along with
the wire gauge to be used (based on the rating of the circuit).
Our Neutral is Earthed at the local substation which may be quite a
distance from the property.

Depends on what you consider a "substation".

E.g., here, there is probably one main "substation" for the neighborhood
(~100 residences). This feeds all of the "4-home transformers" in
the nieghbnorhood.

[Actually, there must be at least one other such "feeder" as I know
when this "main transformer" I'm thinking of died, there were
some homes in the neighborhood fed from a different circuit]

I am guessing this "main transformer" also is earthed (?)
We have the same principle and call it equipotential bonding. Though
many rules regarding Earthing arrangements become relaxed if Residual
Current Devices are used.

RCD/GFCI is in *addition* to these requirements. They are mandated
for use in wet locations (outdoors, bathrooms), garages, kitchens,
etc. There are some exceptions that *could* allow non GFCI protection
in these locations -- usually if the service outlets are ~8 ft above
the floor (so a user can't reach them!).

And, other caveats that affect how they are deployed. E.g., some
places will run a "220" circuit into the kitchen (to satisfy the
"two small-appliance counter-top circuits" requirement). This
is neutral plus the two "legs" of the supply (think of our service
as a 220V center-tapped transformer where neutral is the center
tap). This cuts down on wire costs (as the current flowing through
the neutral should be *less* than what it might otherwise be -- if
there are active loads on both "legs").

As both of these circuits are to be GFCI protected, if a ground fault
is detected on *either*, BOTH are disabled. Kinda inconvenient if
you lose *all* your kitchen counter outlets at the same time :-/
 
A

Anthony Stewart

Jan 1, 1970
0
"Anthony Stewart"
** Nope - the differential is between active and neutral.
YOu are correct (Senior's moment)

**Correction**
GFI's trip the breaker based on a differential current between Line and Neutral. ( with the difference assumed to be flowing thru ground )

Actual construction of a GFI uses a current transformer with BOTH Line & Neutral thru the primary path so that the difference is detected.

Trip Levels for GFI are set to 5mA. I agree this designed so that Ul/CSA/IEC approved line filters in products which have Y rated caps to ground for EMI purpose will not trip the breaker. I recall that ground leakage current(from line filter) was set to 0.5mA max per device or 2.5mA max per systemto meet safety requirements and thus not trip the GFI.

If you are getting false trigger GFI, look for any pulse currents are NOT balanced on Line and Neutral ( bad leaky caps in circuit appliance, dust & moisture on exposed conductors or in high humidity zones)

250V / 5mA = 50KOhm leakage which could be the resistance used by the GFI for self test. (20k perhaps for 120/240 V rated device)
 
D

Don Y

Jan 1, 1970
0
Hi Bud,

On 9/22/2013 9:53 PM, Don Y wrote:

A metal water service pipe (10 ft...) is still required to be part of
the earthing system. Not obvious you were saying water service pipe is
not to be used as part of the earthing system, but a lot of people think
that. An additional electrode is now required for new construction.

The latter. "Earth the plumbing" not "rely on the plumbing for earth".

The house I grew up in relied on water main for earth. And, the
water *meter* being metalic (I don't recollect a bonding strap
*across* the meter -- which was highly visible in the basement
workshop)

Here, I was stunned to see this same *apparent* practice (this house
being 30 years NEWER than my childhood home) as I could see the
clamp to the hose bibb located near the panel. On closer inspection,
however, I noticed another earthing conductor embedded in the
stucco heading off to a ground rod.
A stake (ground rod) is easy to install but is the worst of the commonly
used earthing electrodes. For new construction that has footings or
foundations a "concrete encased electrode" is required. It is a good
earthing electrode and a ground rod is not used.


I have overhead distribution, which is 8kV to distribution neutral
(13.8kV phase to phase). The 240/120V secondary neutral is bonded to the
transformer can and earthed at the pole.

That's what I'd remembered when I had overhead service. But, the below
grade service is covered by a large rectangular "box". One would think
the box itself would be earthed if just for safety.

Looking inside doesn't leave you with a nice warm feeling! Lots
of *big* conductors that are "exposed" (relying on the box to
cover them). Makes you wonder how good that bonding strap is
in the event of a car driving into it! :-/

[I was going to upgrade our service, here. Much of the EXPENSIVE
work can be done by the homeowner: trenching, installing plastic
conduit, shading, etc. But, the sight of those big conductors
left me squeamish: "Maybe we can just take this as an opportunity
to CONSERVE!" :> ]
It may be earthed at poles
without transformers. The secondary neutral could be interrupted, as the
hot wires are, where power is supplied by another transformer, but the
neutral is continuous. It has to be continuous because it is also used
as the distribution neutral, and it connects to the distribution neutral
where the 8kV is tapped of the 3-phase supply.

I expect underground would at least connect the secondary neutral to the
transformer can and earth them at the transformer.


In the US, a major function of the N-G bond required at the panel is to
carry fault current back to the transformer. If you have a H-G short,
the fault current takes the ground wire to the N-G bond at the service
and then the service neutral to the transformer. That results in a high
current to trip a breaker. With no N-G bond there would not be a
reliably high current.

(the half of that sentence unsaid is "... thereby allowing the hazard
to persist")

Sort of like designing a pinout for a power cable in a device such
that installing it backwards, *against* the mechanical keying's
wishes causes the power supply to see a short -- instead of
taking out the electronics.
My understanding is some of the UK does not have a "ground" wire in the
utility supply and the building ground is just earthed at the building.
And a RCD main in the UK is to provide a trip in the absence of the high
current above.

No doubt a way of dealing with grandfathering?
Most, if not all, of the exceptions were removed maybe 5 years ago.

Some were silly (e.g., tying the panel to neutral given that
neutral was bonded to earth *at* the panel).
There are a couple changes in the US code that make a common neutral
("multiwire branch circuit") less common.

One is that the supply breaker must now simultaneously disconnect all
the circuits associated with the neutral. (It does not have to be a
common-trip, a listed handle tie can be used.)

I'm not fond of handle tie's (though realize they are an economical
way of doing things) as they are too easily severed. When we moved
in, here, I immediately noticed the tie for the 220V cooler was
split. Someone seeking to be able to turn off the *furnace*
blower (that shared the circuit) while leaving *half* the cooler
circuit live??

:-(
In a business it can be a
real disadvantage to turn off 2 or 3 circuits to work on only one of them.

The other is that in a house most of the circuits now have to be (new
construction) AFCI protected. Like a GFCI breaker, AFCIs require a
separate neutral that goes through the breaker. You could use a 2-pole
breaker but they are expensive. AFCI receptacles are now available, but
in general you can't use them as an alternative to a breaker like you
can with a GFCI receptacle.

Ah, I didn't realize AFCI's were now Code requirements. Bedrooms?
IMHO it is the most confusing of the commonly used chapters.

Problem with all building codes is they are written requiring
a "language lawyer" for proper interpretation. This, IMO, is
counterproductive (code wars, etc.). The code should go to
great pains to explain what it's intent is so folks don't
have to reconcile "conflicting" sections. It's purpose is to
make things *safer*. Imagine if "STOP" signs said,

"GRADUALLY DECELERATE UNTIL FORWARD MOTION HAS BEEN HALTED
FOR A PERIOD SUFFICIENT TO ENSURE ALL FORWARD MOMENTUM HAS BEEN
ABSORBED" (WTF?)

I can recall looking for clarification for a code section that
implied the need for a "divided Jbox" (other than mixing line
and low voltage conductors in the same box). I was never
able to find anyone who could clarify the requirement and
ended up just using *two* Jboxes (instead of drawing attention
to a single *divided* box)

<frown>
 
B

bud--

Jan 1, 1970
0
"bud--"



** Lack of reply here shows this smug dude's total dishonesty.

Ed said that. I agree. You agree. Does anyone disagree?

Also known as reality.
** More smug, pompous crap.



** Not seen outside the USA and not seen in all GFCIs there either.

The subject is GFCIs used in the US (by Don).

It has been a requirement here for a long time, if not from the start.
One datasheet shows it being implemented with 2 parts - it is easy to add.
And you failed to mention that it is not needed to produce tripping in 99%
of practical situations.

Which is irrelevant.

GFCIs have a second CT used to detect N-G shorts and it does not need
load current. You said that is "Hogwash". You were wrong.
So I did.
?


Piss off - bulkhead.

You poor abused thing.
 
B

bud--

Jan 1, 1970
0

Not sure either. It has been a feature for a long time.
** Any GFCI will detect the neutral current that flows when you short N and
G at an outlet. It is often several amps.

In the US, the N and G are at the same potential at the service due to
bonding. That means you need significant load current to get "several
amps" ground current for a N-G short. You would, in general, need 2x
"several amps" to a downstream load using Romex wiring.
 
B

bud--

Jan 1, 1970
0

A metal water service pipe (10 ft...) is still required to be part of
the earthing system. Not obvious you were saying water service pipe is
not to be used as part of the earthing system, but a lot of people think
that. An additional electrode is now required for new construction.

A stake (ground rod) is easy to install but is the worst of the commonly
used earthing electrodes. For new construction that has footings or
foundations a "concrete encased electrode" is required. It is a good
earthing electrode and a ground rod is not used.
You aren't supposed to rely on earth to be the "return" for the
supply. E.g., you can't use the metal frame of an all steel building
to "eliminate the need for a neutral connector" (like you would
in an automobile)

"Earth" never carries current.


Businesses (high power demands) may have their own transformers, etc.
But, individual residences don't.

Here, for example, four homes will be fed off one transformer
(which is located at grade level as our utilities are below grade).

I *assume* there is an earthing conductor there (it's under a
half cubic yard/meter "box")

I have overhead distribution, which is 8kV to distribution neutral
(13.8kV phase to phase). The 240/120V secondary neutral is bonded to the
transformer can and earthed at the pole. It may be earthed at poles
without transformers. The secondary neutral could be interrupted, as the
hot wires are, where power is supplied by another transformer, but the
neutral is continuous. It has to be continuous because it is also used
as the distribution neutral, and it connects to the distribution neutral
where the 8kV is tapped of the 3-phase supply.

I expect underground would at least connect the secondary neutral to the
transformer can and earth them at the transformer.
At the panel, they are equivalent. In the residence, neutral may
differ instantaneously due to IR drops in the neutral conductor.
Because no current flows through "earth", it is always *at* the
same potential as inside the electrical panel.

In the US, a major function of the N-G bond required at the panel is to
carry fault current back to the transformer. If you have a H-G short,
the fault current takes the ground wire to the N-G bond at the service
and then the service neutral to the transformer. That results in a high
current to trip a breaker. With no N-G bond there would not be a
reliably high current.

My understanding is some of the UK does not have a "ground" wire in the
utility supply and the building ground is just earthed at the building.
And a RCD main in the UK is to provide a trip in the absence of the high
current above.
There are rules governing how "good" the earth must be. Along with
the wire gauge to be used (based on the rating of the circuit).
Our Neutral is Earthed at the local substation which may be quite a
distance from the property.

Depends on what you consider a "substation".

E.g., here, there is probably one main "substation" for the neighborhood
(~100 residences). This feeds all of the "4-home transformers" in
the nieghbnorhood.

[Actually, there must be at least one other such "feeder" as I know
when this "main transformer" I'm thinking of died, there were
some homes in the neighborhood fed from a different circuit]

I am guessing this "main transformer" also is earthed (?)
We have the same principle and call it equipotential bonding. Though
many rules regarding Earthing arrangements become relaxed if Residual
Current Devices are used.

RCD/GFCI is in *addition* to these requirements. They are mandated
for use in wet locations (outdoors, bathrooms), garages, kitchens,
etc. There are some exceptions that *could* allow non GFCI protection
in these locations -- usually if the service outlets are ~8 ft above
the floor (so a user can't reach them!).

Most, if not all, of the exceptions were removed maybe 5 years ago.
And, other caveats that affect how they are deployed. E.g., some
places will run a "220" circuit into the kitchen (to satisfy the
"two small-appliance counter-top circuits" requirement). This
is neutral plus the two "legs" of the supply (think of our service
as a 220V center-tapped transformer where neutral is the center
tap). This cuts down on wire costs (as the current flowing through
the neutral should be *less* than what it might otherwise be -- if
there are active loads on both "legs").

There are a couple changes in the US code that make a common neutral
("multiwire branch circuit") less common.

One is that the supply breaker must now simultaneously disconnect all
the circuits associated with the neutral. (It does not have to be a
common-trip, a listed handle tie can be used.) In a business it can be a
real disadvantage to turn off 2 or 3 circuits to work on only one of them.

The other is that in a house most of the circuits now have to be (new
construction) AFCI protected. Like a GFCI breaker, AFCIs require a
separate neutral that goes through the breaker. You could use a 2-pole
breaker but they are expensive. AFCI receptacles are now available, but
in general you can't use them as an alternative to a breaker like you
can with a GFCI receptacle.
As both of these circuits are to be GFCI protected, if a ground fault
is detected on *either*, BOTH are disabled. Kinda inconvenient if
you lose *all* your kitchen counter outlets at the same time :-/

That is true if you use a 2-pole GFCI breaker. It is cheaper to make the
first receptacle on each circuit a GFCI and wire through it. GFCI
breakers are expensive, and 2-pole GFCIs are a lot more expensive.

IMHO it is the most confusing of the commonly used chapters.
 
D

Don Y

Jan 1, 1970
0
Hi Bud,

On 9/22/2013 6:40 PM, Phil Allison wrote:

In the US, the N and G are at the same potential at the service due to
bonding. That means you need significant load current to get "several
amps" ground current for a N-G short. You would, in general, need 2x
"several amps" to a downstream load using Romex wiring.

Well, you could conceivably get GOBS of amps on a neutral-ground
short (flowing in the ground conductor) if the neutral had a high
resistance connection.

E.g., imagine a 10 ohm load from line to neutral with "a couple"
of ohms in the (faulty!) neutral return -- caused by one or more
splices that have degraded/failed over time. The "normal" neutral
current would be V/(10+2) while the "shorted neutral-ground"
current would be V/(10+e) -- e being much smaller than "2".

This is one reason why I never "daisy chain" outlets prefering
instead, to tie the downstream conductor to the upstream conductor
*and* a pigtail (for the local outlet) under a single wirenut.
I've found that relying on the "second set of screws" to carry
the current for the "downstream" loads is a problem waiting
to happen. Whenever you remove the receptacle from the Jbox
(even just to examine it), those screws see some stress as you
try to manhandle the receptacle (esp with 12AWG conductors).

And, the "push in" sort of connections are for folks who opt for
ease of wiring vs. minimizing fire department calls... :<
 
D

Don Y

Jan 1, 1970
0
Hi Ed,

On 9/21/2013 12:00 PM, Don Y wrote:

No it doesn't. See my reply to bud for the details.
He's talking about a short, but what was discussed was
a partial short. The short would be 1.6 ohms or less
per UL 943, while the partial short would be higher,
perhaps as much as 100 ohms.

See my back of napkin analysis as to why this can't be
what I'm seeing...
 
P

Phil Allison

Jan 1, 1970
0
"bud--"
In the US, the N and G are at the same potential at the service due to
bonding. That means you need significant load current to get "several
amps" ground current for a N-G short. You would, in general, need 2x
"several amps" to a downstream load using Romex wiring.

** So fucking what ??

It only takes 5mA ( in the US ) to trip the damn thing.

You are a bullshitting ass.



.... Phil
 
B

bud--

Jan 1, 1970
0
Hi Bud,



The latter. "Earth the plumbing" not "rely on the plumbing for earth".

The house I grew up in relied on water main for earth. And, the
water *meter* being metalic (I don't recollect a bonding strap
*across* the meter -- which was highly visible in the basement
workshop)

Here, I was stunned to see this same *apparent* practice (this house
being 30 years NEWER than my childhood home) as I could see the
clamp to the hose bibb located near the panel. On closer inspection,
however, I noticed another earthing conductor embedded in the
stucco heading off to a ground rod.

My house has a water service pipe as the only earthing electrode. It was
code compliant when installed and is compliant until the electrical
service is replaced.

A metal municipal water system (what I have) will be the best earthing
electrode available at a house. A bond across the water meter has been
required for a long time. Not quite as long - the connection to the
water pipe has to be withing 5 feet of where it enters the house.

A "supplemental electrode" is only required because water service pipes
may be replaced with plastic.

Ground rods are crap. The code requires a resistance of 25 ohms to earth
for a single ground rod, but for 2 rods there is no requirement. What is
the fault current for a hot connected to a 25 ohm rod?
Ah, I didn't realize AFCI's were now Code requirements. Bedrooms?

The 2002 NEC required AFCIs for bedroom circuits.

The 2008 NEC required AFCIs in residences generally where GFCI
protection was not required. The AFCIs are more sensitive than in the
2002 NEC.

All of this is for new circuits.

The 2011 NEC requires AFCI protection for extensions to circuits where
the extension is in an area where AFCI protection is required. Also
requires AFCI protection for replacement receptacles that are in areas
where AFCI protection is required. (Some of this protection can be
provided with AFCI receptacles.)

I have read that the 2014 NEC will require AFCI protection for kitchen
and laundry circuits, some of which also need GFCI protection.

The NEC is only effective when adopted (and sometimes modified) by an
enforcement agency - like a state.
Problem with all building codes is they are written requiring
a "language lawyer" for proper interpretation. This, IMO, is
counterproductive (code wars, etc.). The code should go to
great pains to explain what it's intent is so folks don't
have to reconcile "conflicting" sections. It's purpose is to
make things *safer*.

The current NEC is 8.5 x 11" and 860 pages. It is not intended to
explain how to design or wire or (usually) intent. But there are a
couple good handbooks and endless "how to" books.

"Lawyer language" is necessary to make the code enforceable. If you read
the code much you get used to it. Took me a while to get used to
"grounded conductor" (neutral) and "grounding conductor" (ground wire).
For a few codes back there has been a push to make the NEC more
readable. For instance, the grounding chapter was reorganized.

There shouldn't be "conflicting" sections (I can offhand think of one).
But general rules can be modified by rules for specific instances, and
the rules for a simple task may be found in many different sections.
I can recall looking for clarification for a code section that
implied the need for a "divided Jbox" (other than mixing line
and low voltage conductors in the same box). I was never
able to find anyone who could clarify the requirement and
ended up just using *two* Jboxes (instead of drawing attention
to a single *divided* box)

There are metal dividers to separate sections in a metal box. The box
manufacturer is likely to make dividers that are attached to the box
with screws.

alt.home.repair can usually answer electrical wiring questions.
 
B

bud--

Jan 1, 1970
0
"bud--"


** The subject is as written in the heading - fuckwit.

Why did you say "not seen outside the USA" fuckwit?

It appears to me the "sensing coil" is 2 sensing coils - one on the left
and one on the right.

It is also an international forum and not obvious the breaker is for the US.
** It is extremely relevant.

GFCIs have a second CT to immediately trip on N-G shorts with no load.
Doesn't matter if load current might provide a trip later - the feature
is there. (It is the "hogwash" feature.)

Some of you posts are real useful. Some of them not - like "hogwash".
 
B

bud--

Jan 1, 1970
0
"bud--"

** So fucking what ??

It only takes 5mA ( in the US ) to trip the damn thing.

You are a bullshitting ass.

The ground current is not "several amps" unless the load current is
twice that. Perhaps you could avoid overstatement.
 
P

Phil Allison

Jan 1, 1970
0
"bud--"
Why did you say "not seen outside the USA"

** Simple, very relevant fact.


It appears to me the "sensing coil" is 2 sensing coils - one on the left
and one on the right.

** Possible.

GFCIs have a second CT to immediately trip on N-G shorts with no load.


** This one is different to your example.

http://www.fairchildsemi.com/ds/RV/RV4141A.pdf

No injected current and there is a load present.

Doesn't matter if load current might provide a trip later ..

** It does matter.

It's how all types of GFCIs work.

Not just ones that comply with the latest UL943 spec.

And you are a one trick phoney.



..... Phil
 
P

Phil Allison

Jan 1, 1970
0
"bud--"
The ground current is not "several amps" unless the load current is twice
that.

** Is not the load commonly twice several amps ??

YOU are a BULLSHITTING ASS.

And a one trick phoney.

**** off.
 
D

Don Y

Jan 1, 1970
0
Hi Bud,

On 9/23/2013 8:33 AM, Don Y wrote:

My house has a water service pipe as the only earthing electrode. It was
code compliant when installed and is compliant until the electrical
service is replaced.

Meet my grandfather... :>
A metal municipal water system (what I have) will be the best earthing
electrode available at a house. A bond across the water meter has been
required for a long time. Not quite as long - the connection to the
water pipe has to be withing 5 feet of where it enters the house.

Here, the water pipe enters at one end of the house while the panel
is sited at the other end. I.e., the panel grounds the plumbing,
not the other way around.

Meter is at the street so there's gobs of subterranean pipe between
here and there. OTOH, water softener's are commonly encountered
as soon as the pipe enters the premises. Hence the bonding
across the softener if you wanted to rely on the water supply
for earth.
A "supplemental electrode" is only required because water service pipes
may be replaced with plastic.

Yup. Though I see latest plumbing code requires 1" copper for main.
Ground rods are crap. The code requires a resistance of 25 ohms to earth
for a single ground rod, but for 2 rods there is no requirement. What is
the fault current for a hot connected to a 25 ohm rod?


The 2002 NEC required AFCIs for bedroom circuits.

The 2008 NEC required AFCIs in residences generally where GFCI
protection was not required.

*Everywhere*? I.e., every circuit is either AFCI or GFCI protected?
Lighting circuits? Furnace? ACbrrr? That can get expensive!
The AFCIs are more sensitive than in the 2002 NEC.

All of this is for new circuits.

The 2011 NEC requires AFCI protection for extensions to circuits where
the extension is in an area where AFCI protection is required. Also
requires AFCI protection for replacement receptacles that are in areas
where AFCI protection is required. (Some of this protection can be
provided with AFCI receptacles.)

I have read that the 2014 NEC will require AFCI protection for kitchen
and laundry circuits, some of which also need GFCI protection.

Kitchen (small appliance circuits) have been GFCI for ages.
Though the rest of the kitchen was exempt (dishwasher, disposal,
etc.)
The NEC is only effective when adopted (and sometimes modified) by an
enforcement agency - like a state.


The current NEC is 8.5 x 11" and 860 pages. It is not intended to
explain how to design or wire or (usually) intent. But there are a
couple good handbooks and endless "how to" books.

But, at the end of the day, you are at the mercy of your local
inspector and *his* understanding of the Code. Most places
don't provide a means of "appeal", etc. Which can be amusing
if inspector A says X and followup visit from inspector B says Y!
"Lawyer language" is necessary to make the code enforceable. If you read
the code much you get used to it. Took me a while to get used to
"grounded conductor" (neutral) and "grounding conductor" (ground wire).
For a few codes back there has been a push to make the NEC more
readable. For instance, the grounding chapter was reorganized.

My point is that even "experts" are often unsure as to what the
code actually says for any given situation. Just like two
lawyers reading the same contract can come to two different
conclusions as to how it applies in a specific case.
There shouldn't be "conflicting" sections (I can offhand think of one).
But general rules can be modified by rules for specific instances, and
the rules for a simple task may be found in many different sections.


There are metal dividers to separate sections in a metal box. The box
manufacturer is likely to make dividers that are attached to the box
with screws.

Finding dividers wasn't the problem. Deciding if it was *required*
was the issue, in my case.
 
B

bud--

Jan 1, 1970
0
Meet my grandfather... :>


Here, the water pipe enters at one end of the house while the panel
is sited at the other end. I.e., the panel grounds the plumbing,
not the other way around.

If there is a metal water service it is being used as an earthing
electrode. If you connect to the water pipe why isn't it being used as
an earthing electrode?

If the water service pipe is plastic, interior metal water pipes are
"bonded" with similar methods.
Meter is at the street so there's gobs of subterranean pipe between
here and there. OTOH, water softener's are commonly encountered
as soon as the pipe enters the premises. Hence the bonding
across the softener if you wanted to rely on the water supply
for earth.

New installations require the connection to be within 5 feet of where
the water pipe enters the building. In the past the water pipe was often
used as a conductor.
Yup. Though I see latest plumbing code requires 1" copper for main.


*Everywhere*? I.e., every circuit is either AFCI or GFCI protected?
Lighting circuits? Furnace? ACbrrr? That can get expensive!

120V, 15 and 20A receptacles in "dwelling unit family rooms, dining
rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms,
recreation rooms, closets, hallways, or similar rooms or areas ..."

The branch circuit is protected, not just the receptacle.
Kitchen (small appliance circuits) have been GFCI for ages.
Though the rest of the kitchen was exempt (dishwasher, disposal,
etc.)

Kitchen is counter top receptacles.
But, at the end of the day, you are at the mercy of your local
inspector and *his* understanding of the Code. Most places
don't provide a means of "appeal", etc. Which can be amusing
if inspector A says X and followup visit from inspector B says Y!


My point is that even "experts" are often unsure as to what the
code actually says for any given situation. Just like two
lawyers reading the same contract can come to two different
conclusions as to how it applies in a specific case.

IMHO experts are not often unsure. That is the point of "lawyer language".
 
B

bud--

Jan 1, 1970
0
"bud--"

** Is not the load commonly twice several amps ??

The load is also commonly not twice several amps.

And the N-G trip feature will trip immediately.
YOU are a BULLSHITTING ASS.

And a one trick phoney.

**** off.

What wonderful arguments supporting your opinions.
 
B

bud--

Jan 1, 1970
0
"bud--"

** Simple, very relevant fact.

The relevant fact is what was being discussed was Don's GFCI in the US.

"Outside the US" is not relevant to Don's questions.
** This one is different to your example.

http://www.fairchildsemi.com/ds/RV/RV4141A.pdf

It is the IC Ed talked about. I provided the link.
No injected current

As Ed detailed, there is an injected current. What is the "Grounded
Neutral" CT for?

As is quoted above "GFCIs have a second CT to immediately trip on N-G
shorts with no load."
and there is a load present.

The application circuit shows external loads that trip H-G and trip with
a N-G short, which Ed explained. The IC trips on a N-G short through a
common mode current imposed on H and N, just as I wrote.
** It does matter.

It's how all types of GFCIs work.

Everyone agrees a load will trip a GFCI with a N-G circuit fault.
Not just ones that comply with the latest UL943 spec.

What I wrote is right, as shown by both IC app notes.

Your "hogwash" is hogwash.
And you are a one trick phoney.

You are remarkably dense when you want to be.
 
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