GFCI operation question

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| Arc Fault Circuit Interrupter. The AFCI breakers look like, and wire | like GFCIs. AFCIs trip on arcs. The NEC requires them on new circuits to | bedrooms. The proposed 2008 NEC requires them for all residential 15 and | 20A circuits IIRC (could still be changed though).
And AFCI-only device could be made to work without accessing the neutral of the circuit involved. The issue is the AFCI device needs to use power to function. Possibly that is the only purpose of the neutral pigtail if the device does not include any GFCI function.
I hope the change goes through. But I would like to see local AHJ rules that permit case-by-case exceptions to be made where AFCI devices are found to be incompatible with certain appliances.
And regarding the issue of putting smoke detectors on AFCI protected circuits. The simple solution is keep receptacle circuits and lighting circuits separate, and put the smoke detectors on the lighting circuits. Those circuits should have much less instance of nuisance trips, and would more readily be noticed if they are opened, in case the smoke detector false to alarm.
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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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We had to have smoke detectors on a separate dedicated circuit. Our contractor decided not to sub out the electrical work, and sure looked upset when he learned he had to rewire four levels of smoke detectors.
S
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snipped-for-privacy@ipal.net wrote:

But all AFCIs include a 30mA GFCI as part of the protection. (That is not the same as a 6mA GFCI for shock protection of people.)

Just to be clear, lighting circuits that include bedrooms have to be on an AFCI. (I think that is what you said.)
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| snipped-for-privacy@ipal.net wrote:
|> |> | Arc Fault Circuit Interrupter. The AFCI breakers look like, and wire |> | like GFCIs. AFCIs trip on arcs. The NEC requires them on new circuits to |> | bedrooms. The proposed 2008 NEC requires them for all residential 15 and |> | 20A circuits IIRC (could still be changed though). |> |> And AFCI-only device could be made to work without accessing the neutral |> of the circuit involved. The issue is the AFCI device needs to use power |> to function. Possibly that is the only purpose of the neutral pigtail if |> the device does not include any GFCI function. |> | | But all AFCIs include a 30mA GFCI as part of the protection. (That is | not the same as a 6mA GFCI for shock protection of people.)
I've seen some that don't. Those were from Cutler-Hammer, the company that makes AFCI without GFCI, AFCI with 30maGFCI, and AFCI with 6maGFCI.
If the NEC ends up requiring the GFCI function, then the ones without GFCI would likely end up being no longer made. But right not it is not clear what the NEC requires NOW (2005 code) or will require (2008 code). All we know is that the scope of where AFCI is required appears to be expanding.
|> And regarding the issue of putting smoke detectors on AFCI protected |> circuits. The simple solution is keep receptacle circuits and lighting |> circuits separate, and put the smoke detectors on the lighting circuits. |> Those circuits should have much less instance of nuisance trips, and |> would more readily be noticed if they are opened, in case the smoke |> detector false to alarm. |> | | Just to be clear, lighting circuits that include bedrooms have to be on | an AFCI. (I think that is what you said.)
All the circuits supplying outlets in the bedrooms must be AFCI protected.
The issue with smoke detectors is more complex. I do believe they must be on AFCI, and I think that is appropriate. I do not expect the smoke detectors to be any source of nuisance trips. Thus it might seem to be a good plan to put them all on their own circuit. But I don't trust that they will alarm when the power is lost. The reason is because that would cause problems in utility outages. Do you want all your smoke detectors beeping when a storm knocks out your power? But what if the branch circuit the smoke detectors are on loses power. You might not even notice that a problem exists. Connecting smoke detectors with receptacles is a bad idea becauseof two reasons. Either the receptacle might not even get used, or the receptacle's usage might be the source of excess nuisance trips. That could compromise the safety of the smoke detectors. My idea is to put them on the same circuit as regularly used overhead lights, such as hall lights or stairway lights. That way, if there is a circuit trip that does affect the smoke detectors, you will be alerted to a problem with that breaker, and motivated to correct it.
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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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snipped-for-privacy@ipal.net wrote:

Smoke detectors that are designed to be interconnected will usually have a backup battery and will chirp every so often if power is lost.
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Tom Horne

Well we aren\'t no thin blue heroes and yet we aren\'t no blackguards to.
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Thomas D. Horne, FF EMT wrote:

Have a reference handy for AFCIs without 30mA ground fault detection?

(There was a proposal for the 2008 NEC to require that but it was rejected.)

Do they chirp if the battery is dead? Removed? I havn't played with them.
The way I understand the 2008 NEC-ROP, NFPA 760 requires smoke detectors that are on AFCI circuits have a secondary power source (battery). Another hidden requirement.
IMHO requiring smoke detectors to be on an AFCI circuit lowers overall fire safety and is dumb.
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| Have a reference handy for AFCIs without 30mA ground fault detection?
Some have 5ma GFCI and some have no GFCI:
Page 22: http://www.eatonelectrical.com/unsecure/cms1/TB00300001E.PDF
Pages 3 and 4: http://www.eatonelectrical.com/unsecure/cms1/TD00308001E.PDF
Page 1: http://www.eatonelectrical.com/unsecure/cms1/TD01201036E.PDF
| The way I understand the 2008 NEC-ROP, NFPA 760 requires smoke detectors | that are on AFCI circuits have a secondary power source (battery). | Another hidden requirement. | | IMHO requiring smoke detectors to be on an AFCI circuit lowers overall | fire safety and is dumb.
I'm not convinced of that, yet.
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Those without GFCI protection are intended for use in habitable and non-habitable spaces not requiring ground fault protection (living rooms and the like.)
Those with 5ma GFCI protection are intended to serve bathrooms, kitchens and anywhere where a standard GFCI is required.
Those with 30ma GFCI is designed to serve residential equipment noted in the NEC requiring 30 ma GFCI (actually termed GFEP to differentiate between the two.) Article 426.28 only requires ground fault protection for equipment, no personnel and that's to only place it can be used to meet code. To protect personnel, you must use 5ma protection.
wrote:

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| Those without GFCI protection are intended for use in habitable and | non-habitable spaces not requiring ground fault protection (living rooms and | the like.) | | Those with 5ma GFCI protection are intended to serve bathrooms, kitchens and | anywhere where a standard GFCI is required. | | Those with 30ma GFCI is designed to serve residential equipment noted in the | NEC requiring 30 ma GFCI (actually termed GFEP to differentiate between the | two.) Article 426.28 only requires ground fault protection for equipment, no | personnel and that's to only place it can be used to meet code. To protect | personnel, you must use 5ma protection.
This is along the lines of what I expected, and certainly sounds very reasonable. Still, the required ground fault protection can be had with an AFCI that has no GFCI, or only has 30ma GFCI, as long as the 5ma GFCI receptacles are also used, where the GFCI people protection is required. Whether one would want to do it that way is another matter.
In a bathroom, there is an advantage to having the ability to reset the GFCI device right there. That advantage may or may not be relevant for a kitchen. Other areas like a garage are probably not much of a concern.
I have been told, but have never sacrificed a device to verify, or set up the appropriate test, that GFCI receptacles open BOTH the hot wire AND the neutral wire when they trip. If so, why is that? Is it to offer at least some protection even when the device is miswired? Or is there even some risk with voltages on the neutral wire?
I do believe some neutral wire risk exists. It's certainly not as much as for the hot wire, usually in terms of voltage, and in terms of exposure events. One example of when the risk is high is when there is a open in in the supply neutral. But the chance of that happening coincident with contacting the neutral to ground, is much lower than either alone. The other risk is the voltage present as a function of the voltage drop along the supply neutral from the point of bonding to the point of contact. That's generally a very low voltage, though it can vary with loading on the system. Still, I'd feel safer having an interruption mechanism that will open BOTH wires together when tripped.
Suppose you have an AFCI that includes GFCI protection, either at the 5ma level or the 30ma level, followed by a GFCI receptacle. Leakage from the neutral to ground would still result in a trip. But can it be guaranteed that the receptacle device will always open? Perhaps the breaker will open first, and de-energize the circuit before the receptacle can open, leaving the neutral wire still connected. To be assured that the receptacle will trip, I'd have to have no GFCI in the breaker, and place the GFCI protection in the receptacle, assuming it is designed to open the neutral.
If I am forced to put GFCI protection in the breaker along with the AFCI protection, or if GFCI receptacles don't actually have neutral contacts that can be opened, I do have a fallback plan. I would run the circuit through a secondary box containing a 2-pole normally open electrically closed contactor. The circuit would run through these contacts. The coil would be powered from the supply side. If the breaker opens the hot wire, the coil will de-energize and open both wires. It won't be as quick an open since such contactors aren't listed for GFCI protection. But at least it will be something that can prevent certain problems. For shared neutral circuits, this would be a 3-pole contactor with a 240 volt coil. These are avalable from Square-D and Cutler-Hammer. One issue that some people might be concerned with is the constant power used by the coil, 24x365xN.
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snipped-for-privacy@ipal.net wrote:

30mA ground fault detection in an AFCI is for arc protection. Far as I know all AFCIs include it (though I need to look harder at phil's 2nd link). Arcs can produce carbon paths which, if a ground is available, can produce ground fault currents. That may produce a trip before there is an arc or before an arc is detected.
In the Consumer Product Safety Commission paper at: http://www.cpsc.gov/volstd/afci/AFCIFireTechnology.pdf that is explained on pdf page 14.
Phil has a link in another thread to: http://www.eatonelectrical.com/unsecure/cms1/AFCI_UL_SPECIAL_SERVICES_INVESTIGATION.PDF which is a UL investigation showing that a "glowing connection" at a receptacle binding screw may (or may not) cause an AFCI trip through the 30mA ground fault function.

I have read in newsgroups (so it must be true) that both poles are opened for hot-neutral-reverse protection.
GFCIs (5mA) are now required to not work with reverse load-line terminal wiring. (Previously the load terminals connected to the receptacle.) I don't think you can do that without double pole contacts line-receptacle and line-load. And I don't think it can be done without that being a NO contact that requires the device to be powered to connect (which it wouldn't be if the line-side neutral was open).
In both cases testing can be easily done without a hammer but so far I have been too lazy.

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Here's a good place to learn more. http://www.cpsc.gov/CPSCPUB/PUBS/afcifac8.pdf#search=%22afci%20ground%20fault%22
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| |> 30mA ground fault detection in an AFCI is for arc protection. Far as I |> know all AFCIs include it (though I need to look harder at phil's 2nd |> link). | | Here's a good place to learn more. | http://www.cpsc.gov/CPSCPUB/PUBS/afcifac8.pdf#search=%22afci%20ground%20fault%22
Sounds like we are now back to the beginning.
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A "neutral" is not defined in the NEC, but is described in Article 310.15(B)(4) as carrying "only the unbalanced current from other conductors...".
In a 120 volt (lighting) circuit, the current is carried on both the white (or "grounded") conductor and an "ungrounded (usually black, but not necessarily) conductor. The term "neutral" refers to the neutral connection at the transformer; the center-tap. In a pure 240 volt circuit, current flows on the two phase conductors and a white (or grounded) conductor in not even needed. By introducing 120 volt circuits, the white forms one of the return legs, and carries current. (240 v between the ungrounded legs, 120 v from either leg to the neutral.)
In Europe, the term "neutral" does include a grounded conductor in a 120 v circuit. In the states the term is used interchangeably but in error.


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| A "neutral" is not defined in the NEC, but is described in Article | 310.15(B)(4) as carrying "only the unbalanced current from other | conductors...".
"Neutral conductor" is defined in the NEC. The term is used in many places. I fully understand what a neutral is. Are you raising an issue about its common or formal usage?
| In a 120 volt (lighting) circuit, the current is carried on both the white | (or "grounded") conductor and an "ungrounded (usually black, but not | necessarily) conductor.
If you are wanting to get very specific, it's the insulators that have the color. The current is carried on the (usually) copper metal (with a magnetic field, of course).
The code requires the grounded conductor be identified well (e.g. continuous color, not just marked at each end). Others have more leeway.
| The term "neutral" refers to the neutral connection at the transformer; the | center-tap. In a pure 240 volt circuit, current flows on the two phase | conductors and a white (or grounded) conductor in not even needed. By | introducing 120 volt circuits, the white forms one of the return legs, and | carries current. (240 v between the ungrounded legs, 120 v from either leg | to the neutral.)
You could tap the transformer off-center a bit if you wanted to and have 115 volts on one side and 125 volts on the other side. Would you call that a "neutral"?
So tell me ... what happens if you have a couple of very low power factor loads, one on each 120 volt side, where one is very inductive and the other is very capacitive? Now how much current flows on the "neutral"?
| In Europe, the term "neutral" does include a grounded conductor in a 120 v | circuit. In the states the term is used interchangeably but in error.
I see very little use in error in the US. Neutral does not mean grounded, but it generally implies that because that is the required way to wire it up. See NEC 250.26(2). The two terms "neutral conductor" and "grounded conductor" do have different meanings, but are associated with the same wire because that is the required way.
Single phase in Europe is generally 2-wire service. You can still call one wire neutral because it may well be the wire connected to the real neutral point in either a single phase transformer (center tapped 230/460) or a three phase transformer (connected to the star common). But it is grounded and thus (also) correct to call it a grounded conductor. If the service is coming from a 2-wire transformer all by itself, then it's not really neutral; it's just grounded.
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In Europe, there are no 120V circuits, and "neutral" is a supply current carrying conductor which is at or near ground potential.
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|> In Europe, the term "neutral" does include a grounded conductor in a 120 v |> circuit. In the states the term is used interchangeably but in error. | | In Europe, there are no 120V circuits, and "neutral" is a supply | current carrying conductor which is at or near ground potential.
But that doesn't really change the meaning's origin. The first power systems were three phase to drive motors. I don't know if delta was used much way back when, but with star/wye configurations, you do have a genuine neutral. When single phase at 240v is taken from that, the neutral is still there. It just doesn't have enough phases brought in to take the neutralizing role there.
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     snipped-for-privacy@ipal.net writes:

The neutral role is still there, i.e. it's still at or near ground potential.
Now there are some single phase supplies in europe which don't have a neutral, but they are much less common and only in a few countries (not UK). An example is a single phase supply from a corner grounded delta, where both of the lines are taken from a non-grounded corner.
There are also IT supplies which are isolated with just a resistance to ground to prevent the secondary capacitively floating up to the much higer primary voltage. Strictly the side with the resistor to ground is still called a neutral, although it might be some way from ground potential. Again, I believe some parts of Europe use this, but it only occurs in the UK on standalone generators, not from the public supply.
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| snipped-for-privacy@ipal.net writes:
wrote:
|>|> In Europe, the term "neutral" does include a grounded conductor in a 120 v |>|> circuit. In the states the term is used interchangeably but in error. |>| |>| In Europe, there are no 120V circuits, and "neutral" is a supply |>| current carrying conductor which is at or near ground potential. |> |> But that doesn't really change the meaning's origin. The first power |> systems were three phase to drive motors. I don't know if delta was |> used much way back when, but with star/wye configurations, you do have |> a genuine neutral. When single phase at 240v is taken from that, the |> neutral is still there. It just doesn't have enough phases brought |> in to take the neutralizing role there. | | The neutral role is still there, i.e. it's still at or near ground | potential.
But that's not what the meaning of neutral is. It's neutral whether it is grounded or not. In cases where there are 2 or mroe phases, the idea is that when things are in balance, there is no current on the neutral. It was neutralized by the balance. But I think the meaning really comes from the neutral point in the transformer winding of the secondary.
| Now there are some single phase supplies in europe which don't have | a neutral, but they are much less common and only in a few countries | (not UK). An example is a single phase supply from a corner grounded | delta, where both of the lines are taken from a non-grounded corner.
Apparently these are older connections. From what I gather, the first power in much of Europe in the late 1800's was 220/127 three phase. It appears that predated Edison supplying light to New York, so it seems he took the 220 voltage and split it for DC. He likely also realized, in all his light bulb work, that a lower voltage worked better on the filament. I've heard that the 220/127 can still be found in some remote locations like way north Norway and rural parts of Spain. A friend has reported seeing the remnants of 220/127 wiring in buildings in Germany predating WW1.
| There are also IT supplies which are isolated with just a resistance | to ground to prevent the secondary capacitively floating up to the | much higer primary voltage. Strictly the side with the resistor to | ground is still called a neutral, although it might be some way from | ground potential. Again, I believe some parts of Europe use this, | but it only occurs in the UK on standalone generators, not from the | public supply.
The reason they use that resistance instead of a solid ground is to avoid single fault failures. But during that time, one hot line is now grounded.
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wrote:
[snip]

Even when that's exactly what you want.

[snip]
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87 days until the winter solstice celebration

Mark Lloyd
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Mark Lloyd wrote:

When the supply wires are connected to the LOAD terminals on old GFCIs, the GFCI receptacle is not protected - it is live even if the GFCI is tripped. (I believe the downstream circuit, which would be connected to the LINE terminals, is protected.)
Under the new UL standard, which I think was adopted about 2 years ago, if you connect supply wires to the LOAD terminals the GFCI receptacle and LOAD terminals will always be dead.
I may have tried to say that with too few words.
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