AFCI Breakers

[iwire]

Now, one thing I will agree with is the benefit of insulation testing at the completion of a job. We do that often as it is a called for in many of our job specification.

 

[Tony S]

I?m giving up, I?m right in that everything should be tested and recorded and you?re right because there are more of you.

Now if someone comes up with a logical explanation of why things shouldn?t be tested other than MCB?s I?ll listen. With MCB?s it would be a case of throw away after testing making it a bit of a waste of time really.
I think I?d rather be certain that a device will operate within its set parameters than rely on what it says on the box.
According to the label on my breakfast cereal I?ll loose weight.

Regarding my statement about the RCD exploding, a 125A RCD is a bit unforgiving with an internal short circuit.

I?ve done very few domestic installs, it works out at about one every eight years. That is the reason I had another electrician test my flat. I?m authorised to work and test up to 11KV and yet I can?t test a domestic install.

 

[iwire]

I?m giving up, I?m right in that everything should be tested and recorded and you?re right because there are more of you.

In other words you are right because you say you are right.

Now if someone comes up with a logical explanation of why things shouldn?t be tested other than MCB?s I?ll listen.

I have not seen anyone suggest testing is not needed we just differ in opinion on how extensive the testing has to be.

As far as the reason why I do not support this ramp test you suggest is because that is more info than needed to determine if the GFCI is functioning. You have told us that the equipment is expensive and requires regular calibration. I never support requirements that spend money needlessly.

I think I?d rather be certain that a device will operate within its set parameters than rely on what it says on the box.

And again, the test button does make sure of that.

Regarding my statement about the RCD exploding, a 125A RCD is a bit unforgiving with an internal short circuit.

I thought you were talking about a GFCI, I have never heard of a GFCI exploding when the test button is pushed. It seems like these RCDs need better quality control or better design if pushing the trip button causes a destructive failure.

 

[chuck@tracyelectricinc.co]

Check for a bad wire nut connection, or a loose screw shell in the lamp holder, quit often the rivet or screw securing the screw shell is defective from the factory, the AFCI will detect the arc to the screw shell and trip, same with a wire that is slipping out from the wirenut.

 

[mbrooke]

OK, why is it that previously in this thread I was told how much simpler an RCD was than a GFCI?

An RCD is simpler because it contains no electronics: (see attached pictures)

A toroid + solenoid is a lot less likely to fail, nuisance trip or do this:

http://forums.mikeholt.com/attachment.php?attachmentid=750&stc=1&d=1188559293

http://ecmweb.com/site-files/ecmweb.com/files/archive/ecmweb.com/mag/903ecmFORENpic2.jpg


The only seem complex to you because in some other parts of the world GFCIs/RCD/GFPs ect must all undergo testing to produce trip data regardless of their internal design. If a US GFCI was shipped and used in the UK it to would have to under go elaborate testing under UK regs.

What 'wear' the parts are stationary other than a trip. If anything they might stick due to non-use but that is a problem every molded case circuit breaker has and we don't test them either. They are far to inexpensive to bother doing load testing of them. If they are suspect they are simply tossed out.

These trip mechanisms can seize from foreign infiltration like bugs, water ect. Any grease can dry out inside. I have pushed test buttons on outdoor GFCIs that would not even move. Even if the mechanical parts are ok, their is a printed circuit board that can act up.

The mechanical parts are the same as our standard thermo-magnetic trip breakers. There is no wear unless they happen to be tripping all the time and my experience tells me that wear makes them subject to early triping not late.

Depends. For a GFCI breaker yes, for a GFCI outlet, that could be debated.

If the resister burns out the test button would not trip it so it would not pass the test. In other words .... no danger.

And if the test button isn't working then the RCD would immediately be labelled defective without further testing.

Call me very doubtful.

We know!

I am sorry you cant understand it but that does not change the fact it is enough.

From a North American document stand point you are correct, it is enough. From a UK regulation standpoint its not.

Im sure in reality the test button is sufficient in most cases, but why not rest assured for those cases where something might fly under?

I know you will think this is also over the top, but in the UK all completed installations must undergo an "earth fault loop impedance test" which in a nut shell must show the EGC is intact (not broken).

Might be excessive, but in the rare event an open ground exists (a life safety hazard) why not find out before something goes horribly wrong?

No need for that information, it only makes pretty reports.

I like pretty

One the breaker leaves the factory the trip time and trip level is not going to drift unless the mechanical parts seize up ....... and they it wont test with the button.

Any documents supporting that statement, or that the circuit board/ mechanical trip behavior will never change?

 

[mbrooke]

Now, one thing I will agree with is the benefit of insulation testing at the completion of a job. We do that often as it is a called for in many of our job specification.

But not under the NEC. I know many, many sparkies who do not test switch gear let alone residential installations. About the only thing the NEC wants you to test is a manufactured trailer home. Just because its a house doesn't mean install error doesn't exist.

 

[mbrooke]

If it is within the standard, do we really care about the exact numbers? I expect that the GFCI standard specifies the resistance of the resistor or the amount of current that it should flow at 120 volts. I don't have a copy of the standard to verify that. Most GFCIs trip much quicker than what the standard permits. I think if there was any delay, even a delay much less than the 3.7 seconds that the standard permits, I would replace the device.

Does such a standard even exist? For every GFCI? Not saying it does not, (you know more about this then I do) but to this day cant find anything about it available to the public or official.

 

[mbrooke]

These worthless devices were forced down our throats by overzealous jackasses who call themselves code authorities, who never met a rule they didn't like. They have long refused to address the issue that inferior wiring methods (chiefly backstabbing) have caused most of the problems the devices were supposed to "fix". I have replaced dozens of backstabbed devices that were "protected" by AFCI breakers that never tripped.

I have been fortunate to see only a few afci's nuisance tripping but am still angry at how much business has been lost because of the increased costs brought on by these devices.

Code authorities, open wide so we can shove them back down YOUR throats. Manufacturers, who probably bribed the authorities, you get in line too.

I think your post says it all! :thumbsup::thumbsup::thumbsup::thumbsup::thumbsup:


I particularly agree with your views on backstabbing. Backstabbing is an inferior method which I am sure has been responsible for many fires yet nothing is being done about it, let alone an investigative report.

Which leads me to glowing connections. It is believed high resistance connections are responsible for 90%-95% of all electrical fires, yet to this day absolutely nothing has been done to address them. Every expert knows of the risk, even grandma knows a loose connection can burn down a home, yet its the pink elephant in the room no one wants to talk about.


Yes Eaton has a patent for an electronic glowing connection interrupter (which if anything should have been advanced, brought to the market instead of AFCIs), yet you can not tell me for decades on end no one has at least tried to come up with something simple be it self fusing connections or what to address them. Again, the fact back stabbed outlets are permitted and even what the British call "fire nuts" shows the NEC has absolutely no interest in eliminating electrical fires, more like profiting from them.

Not ranting at you though, just blowing off steam at the CMP

 

[iwire]

An RCD is simpler because it contains no electronics: (see attached pictures)

A toroid + solenoid is a lot less likely to fail, nuisance trip or do this:

http://forums.mikeholt.com/attachment.php?attachmentid=750&stc=1&d=1188559293

http://ecmweb.com/site-files/ecmweb.com/files/archive/ecmweb.com/mag/903ecmFORENpic2.jpg


The only seem complex to you because in some other parts of the world GFCIs/RCD/GFPs ect must all undergo testing to produce trip data regardless of their internal design. If a US GFCI was shipped and used in the UK it to would have to under go elaborate testing under UK regs.

Hold on there partner.

I don't know anything about RCDs, I have never claimed they are complex or basic. I was pointing out that you and Tony S are saying entirely different things about them.

You have said they are simpler than GFCIs. Tony says they are more complicated than GFCIs.

These trip mechanisms can seize from foreign infiltration like bugs, water ect. Any grease can dry out inside. I have pushed test buttons on outdoor GFCIs that would not even move. Even if the mechanical parts are ok, their is a printed circuit board that can act up.

So in other words it did not pass the test.

Seems like the test button did its job.

Depends. For a GFCI breaker yes, for a GFCI outlet, that could be debated.

No debate, the 'wear parts' of a GFCI outlet are not the parts that have anything at all to do with the trip characteristics.

And if the test button isn't working then the RCD would immediately be labelled defective without further testing.

No kidding.

From a North American document stand point you are correct, it is enough. From a UK regulation standpoint its not.

I work and live in North America, this forum is primarily North American. My comments are all based on that fact.

I am not trying to change what other areas do or require.

Im sure in reality the test button is sufficient in most cases, but why not rest assured for those cases where something might fly under?

Because the idea is practical safeguarding not absoulutly safeguarding. The cost to benefit has to be there.

I have not seen you post any links or info showing that things are 'flying under' that seems to be an assumption you are making.

I know you will think this is also over the top, but in the UK all completed installations must undergo an "earth fault loop impedance test" which in a nut shell must show the EGC is intact (not broken).

Actually I do not think that would be over the top at the time of completion. I take grounding pretty seriously.

Over the top would be requiring that same test on a annual basis.

Might be excessive, but in the rare event an open ground exists (a life safety hazard) why not find out before something goes horribly wrong?

I agree, one of the things I work on often is parking lot lighting and I honestly worry about the condition of the EGC. Often these circuits operate at 277 volts to ground and it is not that unusual for a hot conductor in the pole to short to to the pole due to movement from wind and time. If the EGC is not intact they pole will be live. That scares me, I never want to hear someone was hurt or killed by a pole I was the last to work on.

I like pretty

Great, test all you want just don't try to push it on the rest of us as a regulation.

Any documents supporting that statement, or that the circuit board/ mechanical trip behavior will never change?

I am claiming that the electronic parts will either work or not and that their time / current levels will not change over time.

I have not claimed the mechanical trip parts will not wear out or gum up. However the trip button will determine if the parts are gummed up. If the parts were out my experience tells me the breaker is gets easier to trip.

All the mechanicals inside the GFCI breaker are the same as in a standard molded case breaker. Do you think standard molded case breakers should be load bank tested?

How about you posting some legitimate evidence or statistics that shows the test button does not do the job?

 

[iwire]

A little reading for you.

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=20553

Electrical/Electronic Technical Note 91-1

December 18, 1991

How to Test the Operation of a GFCI

The Office of Electrical, Electronic, and Mechanical Engineering Safety Standards does not recommend the use of GFCI testers as a means of determining compliance with ?1926.404(b)(1)(ii), as such testers may not produce accurate results. Ground-fault circuit interrupters incorporate a testing circuit that can be used to determine whether or not the device itself will function as intended. No further tests are necessary.

Any GFCI tester that puts a resistive load between the ungrounded circuit conductor and the equipment grounding conductor1 to measure the current at which the device trips is subject to errors due to voltage fluctuations. If the circuit voltage is 100 volts, the tester could indicate that a GFCI tripped at 7.2 mA when it would actually have tripped at 6.0 mA. (See attachment.)

Testers like the Greenlee model 5708,(2) described in Mr. Loebach's memorandum (attached), cannot produce a reliable indication of the trip level of a GFCI. This device sends a 200-millisecond pulse through the grounding conductor at various current levels. A GFCI may not trip at minimum current levels (that is, 6-20mA) in such a short period of time. (For example, UL Standard 943 allows trip times of up to 1.5 seconds at 15mA.) This tester provides a 4-second interval between pulses and cannot be adjusted to provide a longer pulse or a shorter interval.

Additionally, an employer cannot reasonably be expected to know at what level his or her GFCIs trip. A reasonable person would only expect the employer to check them periodically using their built-in test mechanisms. Assuming that test equipment could accurately detect a GFCI that trips at too high a current, the employer should not be penalized for conditions beyond his or her normal control.

__________________________

(1) Deliberately putting current through the equipment grounding conductor is undesirable and, under certain conditions (for example, in a hazardous location), is unsafe.

(2) This device is not currently approved by a nationally recognized testing laboratory and does not meet OSHA's electrical safety standards. Therefore, it should not be used by OSHA compliance staff.

A citation in such cases may be warranted -- penalties are not.

The supervisory circuit built into a ground-fault circuit interrupter is designed to cause tripping even when the circuit voltage is 85 percent of rated voltage (102V for a 120-volt device). At rated voltage, the current employed by the supervisory circuit may not exceed 9mA. Thus, it gives an indication of the operability of the GFCI at currents approaching the trip level. It may not give an indication of whether the GFCI actually opens the circuit; however, this can easily be determined by plugging utilization equipment into the circuit in question.

For these reasons, the Office of Electrical, Electronic, and Mechanical Engineering Safety Standards recommends that the compliance staff use the test button on a GFCI in combination with an attached load plugged into the circuit to be tested rather than a GFCI tester. A plug-in ground continuity tester would suffice as an attached load. If the lights on the continuity tester go out when the test button is pressed, the GFCI can be assumed to be operating correctly. If the lights stay on or if the test mechanism fails to operate, the GFCI is faulty, and a citation would be warranted.

 

[iwire]

More

http://www.nema.org/Products/Documents/NEMA-GFCI-2012-Field-Representative-Presentation.pdf

UL GFCI Tests

Every GFCI must pass the following end-of-line manufacturing tests:

1.no trip below 4mA (no load)

2.must trip at 6mA (no load)

3.no trip below 4mA (with load) at rated voltage

4.must trip at 6mA (with load) at rated voltage

5.must trip with 2 ohm grounded neutral

6.must trip within 25 ms with a 500 ohm fault

7.must trip with test button at +10/-15% rated voltage

8.must not trip with noise test of GFCI Standard

9.calibration test at +10/-15% rated voltage

GFCI Testers

Why are testers used?

?verify operation of the GFCI

?check protection of downstream receptacles

Will not test:

?GFCI calibration

?ALL types of improper installation

?Danger on 2-wire circuits

Will test for some types of improper installation:

?line/load reversal

?which outlets are protected by GFCI

?reverse polarity

?presence of the equipment ground

Benefits of UL943 (GFCI) vs. IEC (RCD)
Increased Safety Benefits

UL943 Max 6 mA - threshold for ?let-go? current.
IEC Min 20 mA - threshold current for ventricular fibrillation.

Receptacle End of Life indication

Grounded Neutral protection

Portable units - Load protection if both supply neutral and ground conductors are open together.

 

[mbrooke]

Hold on there partner.

I don't know anything about RCDs, I have never claimed they are complex or basic. I was pointing out that you and Tony S are saying entirely different things about them.

You have said they are simpler than GFCIs. Tony says they are more complicated than GFCIs.

I don't think Tony ever explicitly said they are more complex. In terms of the testing done in the UK on all RCD/GFCIs, yes, it is far, far more complex. But that is testing only.


In terms of construction, a least involving printed circuit boards, UK RCDs are much simpler having usually no electronics. That was my point in terms of simplicity. A semiconductor device is far more likely to be damaged by voltage transients then an electromechanical device.


Think of those older Westinghouse time dial relays providing over current protection vs an SEL or GE multilin microprocessor controller. Same goal in term of purpose but different construction.

So in other words it did not pass the test.

Seems like the test button did its job.

In this case. But a slow trip?

No debate, the 'wear parts' of a GFCI outlet are not the parts that have anything at all to do with the trip characteristics.

Of course, unless you are pressing the reset button all day it wont break down from friction. But foreign object infiltration, of issues with the circuit board itself are real case problems.




No kidding.

I work and live in North America, this forum is primarily North American. My comments are all based on that fact.

I am not trying to change what other areas do or require.

I know, but the knowledge gained is worth it. :thumbsup: Both sides of the pond have much to offer and can learn from each other in places where the other has succeeded bettering both. Kind of like you scratch my back I scratch yours, in the end both are happier.


My reason for bring up UK RCDs and their design application, being that a similar concept could be applied here providing AFCI protection at a far lower cost.


Not only that, but the fact most UK RCDs have no electronics means the "self test" concept now being required for US GFCIs could in theory be eliminated. Only a matter of time before its applied to AFCI raising their cost even more. The primary driver for self testing GFCIs are electronics that fail when subjected to transients. Couple that with no monthly testing and the risk of no having protection goes up. Only down side is added cost, which again, gets passed on to the consumer.

Yes its true a mechanical device can fail, but unlikely when compared to semi conductors. And if the concern was really about mechanical failures then self testing GFCIs would have done away with them all together

Because the idea is practical safeguarding not absoulutly safeguarding. The cost to benefit has to be there.

Exactly! $37 per breaker is not practical safe guarding, certainly not when a much cheaper concept could do the same.

I have not seen you post any links or info showing that things are 'flying under' that seems to be an assumption you are making.

I am making an assumption, as you are. Let me read up on your links though, you might have supporting evidence.

Actually I do not think that would be over the top at the time of completion. I take grounding pretty seriously.

Then we can agree here, that at least this test, is worth it?

Over the top would be requiring that same test on a annual basis.

That might be extreme.

I agree, one of the things I work on often is parking lot lighting and I honestly worry about the condition of the EGC. Often these circuits operate at 277 volts to ground and it is not that unusual for a hot conductor in the pole to short to to the pole due to movement from wind and time. If the EGC is not intact they pole will be live. That scares me, I never want to hear someone was hurt or killed by a pole I was the last to work on.

30ma GFP might lessen the risk should the EGC become compromised But in all seriousness this is one place where an intact EGC is essential.

Great, test all you want just don't try to push it on the rest of us as a regulation.

Will read up on the facts, then decide.

I am claiming that the electronic parts will either work or not and that their time / current levels will not change over time.

You may be correct, but there is no proof of either me or you being correct.

I have not claimed the mechanical trip parts will not wear out or gum up. However the trip button will determine if the parts are gummed up. If the parts were out my experience tells me the breaker is gets easier to trip.

The trip button may trip them, but at what speed? Ive pressed some buttons and it took literally a second or two, not the instantaneous opening on a new GFCI. In a case like this a GFCI may pass the UL test for a 8ma fault, but a 250ma fault? 80 cycles would be out of compliance Id think. This is where a GFCI would fly under in theory.

However, a tester would accurately catch the trip time.

Another possible scenario, though I have never run across it, would be where one of the contacts gets hung up. The GFCI would still trip, breaking on pole but not the other. Years ago there was a recall of an LICD plug that would do that in some cases.

All the mechanicals inside the GFCI breaker are the same as in a standard molded case breaker. Do you think standard molded case breakers should be load bank tested?

No, for the mechanicals Id think are coved by flipping the toggle. Of course that still wont determine the opening speed but you get my point.

How about you posting some legitimate evidence or statistics that shows the test button does not do the job?

Will see what I can find. Im sure Tony could at least give the UK's reasoning behind it.

 

[mbrooke]

A little reading for you.

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=20553


Electrical/Electronic Technical Note 91-1

December 18, 1991

How to Test the Operation of a GFCI

The Office of Electrical, Electronic, and Mechanical Engineering Safety Standards does not recommend the use of GFCI testers as a means of determining compliance with ?1926.404(b)(1)(ii), as such testers may not produce accurate results. Ground-fault circuit interrupters incorporate a testing circuit that can be used to determine whether or not the device itself will function as intended.

True, because the resistor inside could pass 500ma. Its not known.

No further tests are necessary.

Via set standards, of course. At one time seatbelts were not required for Cars.

Any GFCI tester that puts a resistive load between the ungrounded circuit conductor and the equipment grounding conductor1 to measure the current at which the device trips is subject to errors due to voltage fluctuations. If the circuit voltage is 100 volts, the tester could indicate that a GFCI tripped at 7.2 mA when it would actually have tripped at 6.0 mA. (See attachment.)

This actually supports my claim!

Its true, and would also hold true for the GFCI itself. All the GFCIs I have seen have a fixed resistor, not a voltage compensated testing assembly. So the manufacturer has to intentionally select a lower value to compensate for installations that are within the lower bandwidth of voltage tolerances. This means that supplies at the higher level, like 126.5 volts will produce more current at time of testing.


So again, we have no real idea of what imbalance the GFCI sees under a test, often more to cover low voltage cases. However, a microprocessor testing device can pull the exact current desired with a display screen.

Testers like the Greenlee model 5708,(2) described in Mr. Loebach's memorandum (attached), cannot produce a reliable indication of the trip level of a GFCI. This device sends a 200-millisecond pulse through the grounding conductor at various current levels. A GFCI may not trip at minimum current levels (that is, 6-20mA) in such a short period of time. (For example, UL Standard 943 allows trip times of up to 1.5 seconds at 15mA.) This tester provides a 4-second interval between pulses and cannot be adjusted to provide a longer pulse or a shorter interval.

Yes, a short coming of not using a real tester like those deployed in the UK where parameters can be adjusted over a broad range.

Additionally, an employer cannot reasonably be expected to know at what level his or her GFCIs trip. A reasonable person would only expect the employer to check them periodically using their built-in test mechanisms. Assuming that test equipment could accurately detect a GFCI that trips at too high a current, the employer should not be penalized for conditions beyond his or her normal control.

And he doesn't know either with the self test mechanism. What value did the self test place?

(1) Deliberately putting current through the equipment grounding conductor is undesirable and, under certain conditions (for example, in a hazardous location), is unsafe.

Correct, if the EGC is open, but then this right here claims we shouldn't use those 3 light plug in testers either.

In any case its better to know the EGC is open.

(2) This device is not currently approved by a nationally recognized testing laboratory and does not meet OSHA's electrical safety standards. Therefore, it should not be used by OSHA compliance staff.

A citation in such cases may be warranted -- penalties are not.

Of course.

The supervisory circuit built into a ground-fault circuit interrupter is designed to cause tripping even when the circuit voltage is 85 percent of rated voltage (102V for a 120-volt device). At rated voltage, the current employed by the supervisory circuit may not exceed 9mA. Thus, it gives an indication of the operability of the GFCI at currents approaching the trip level.

Supervisory circuit? If they mean the test resistor, the GFCI pictured has a 10K resistor, (12ma), and further, if the voltage is in the upper limit? Its over 9ma even for a 9ma sized resistor at 120 volts.

It may not give an indication of whether the GFCI actually opens the circuit; however, this can easily be determined by plugging utilization equipment into the circuit in question.

And this is where a tester comes in, checking both Live and neutral have opened. :thumbsup: And no, a 3 light tester wouldn't catch a hung up neutral.

For these reasons, the Office of Electrical, Electronic, and Mechanical Engineering Safety Standards recommends that the compliance staff use the test button on a GFCI in combination with an attached load plugged into the circuit to be tested rather than a GFCI tester. A plug-in ground continuity tester would suffice as an attached load. If the lights on the continuity tester go out when the test button is pressed, the GFCI can be assumed to be operating correctly. If the lights stay on or if the test mechanism fails to operate, the GFCI is faulty, and a citation would be warranted.

But again, this is just comparing a tester vs an internal resistor. Still doesn't give much info on ma during testing, speed, or successful opening of all contacts.



A tester would tell me:

With an immediate imbalance drop;

Time to trip at 3ma, abort after 6 seconds (just to check for nuisance tripping)


Time to trip at 5ma (abort after 13 seconds)


Time at 10ma

Time at 15ma

Time at 30ma

Time at 50ma


Then we do a ramp test to determine the current rise in relation to the trip time.


...............................



Of course this isn't reflecting UK tests but Tony can explain his standardized methods.

 

[romex jockey]

Agreed.......so why not those who have that GREATER knowledge continue to press for change if they believe it is so. Let's face it...the Home Builders Association has the deepest pockets of all of the anti-AFCI proponents and pay for many independent studies and they serve on CMP 2......yet again they FIGHT the AFCI at every chance so why would they have not proposed data on contrary to what the manufacturers claim. Let's not say it is because they are in the pockets of the manufacturers because I know that not be true having worked with both......so.....so much theory....

So with all the passion to debunk AFCI's.....why would someone not put together the data to prove them wrong and take all the glory for saving mankind from needless wasted spending......WHY?

My state amended for AFCI usage a full cycle before the rest of the nation , we went bat sh&t crazy installing the first version here. In fact i was convinced that this magic widget was the ultimate cure for all the K&T we still have (we're still lousy with it btw) , and sold them per manufacturers shtick that they would protect circuitry from all electrical fire.

As time went on i dug, read, and understood how wrong i was.

That said, all the trade icons questioned them, including this sites owner. NFPA EE's questioned them. Finally the grandaddy icon of afci technology himself, a PROPONENT of the technology forwarded a dissertation to the IEEE in '12

He , along with multitudes of others, also forwarded many many ROP's to CMP-2 . In fact if there were some sort of way to account for which CMP was hammered most, i'd wager it #2 via 210.12 B

ALL these folks had the same basic aim.

They wished to clarify what the AFCI does and does not do. So what more could you want Master?

That our illustrious CMP,CPSC,NRTL,UL et all lettered bureacractic oversight, as well as our shill trade rags have remained silent is moot Master.

~RJ~

 

[iwire]

I don't think Tony ever explicitly said they are more complex.

Example

Your GFCI is identical to a 3 pole RCD baring the leakage current rating.

Tony says they are identical plus leakage current rating. I have to assume, and maybe incorrectly, that this leakage current rating requires a more complex device.

You say

The sad part is US GFCI are full of electronics, where UK RCDs are just a toroid coil and a solenoid?

Do you see the difference there?

 

[mbrooke]

More

http://www.nema.org/Products/Documents/NEMA-GFCI-2012-Field-Representative-Presentation.pdf

Benefits of UL943 (GFCI) vs. IEC (RCD)
Increased Safety Benefits

UL943 Max 6 mA - threshold for ?let-go? current.
IEC Min 20 mA - threshold current for ventricular fibrillation.

Based on what, or who? Not what most charts say in regard to ventricular fibrillation. See pic, and I will see if I can find the Mike Holt graphic.

Receptacle End of Life indication

Needs more elaboration.



Grounded Neutral protection


This really has no purpose. Its done by adding an injection system to the electronics. A standard RCD will not trip immediately like a GFCI if the circuit has no load, but it will when load is applied. The big issue is again is electronics.

Portable units - Load protection if both supply neutral and ground conductors are open together.

Not sure what they mean. FWIW UK RCBOs have open neutral protection, as in those white leads.

 

[romex jockey]

I'm told an AFCI has a microprocessor, that actually catalogs and 'remembers' arc signatures>



So how does the test button 'test' for it?

~RJ~

 

[iwire]

True, because the resistor inside could pass 500ma. Its not known.

Yes, that is about an external plug in tester which is not the same as the internal test.

Via set standards, of course. At one time seatbelts were not required for Cars.

There is no need to increase standards requirement when the existing ones are working fine. You have yet to post anything showing that existing standards are causing unsafe conditions.

There was a clear and easily provable need for seatbelts.

This actually supports my claim!

Sure with external testers.

If you actually read the text it explains that is not the case with the internal test button operation.

Its true, and would also hold true for the GFCI itself. All the GFCIs I have seen have a fixed resistor, not a voltage compensated testing assembly. So the manufacturer has to intentionally select a lower value to compensate for installations that are within the lower bandwidth of voltage tolerances. This means that supplies at the higher level, like 126.5 volts will produce more current at time of testing.

Above 126.5 volts is a problem in in itself. Do you think all electrical equipment needs to be designed to operate safely far above or below its nominal voltage rating?


So again you are looking for absolute safeguarding without showing any evidence it is needed,

So again, we have no real idea of what imbalance the GFCI sees under a test, often more to cover low voltage cases. However, a microprocessor testing device can pull the exact current desired with a display screen.

Show me the injuries or property damaged caused by GFCIs failing to test properly operating out of their voltage range.

Yes, a short coming of not using a real tester like those deployed in the UK where parameters can be adjusted over a broad range.

I agree those plug in testers are not a good way to go. Never said they were. I have been saying the internal tester does the job.

And he doesn't know either with the self test mechanism. What value did the self test place?

The standards tell us that the internal test is all we need.

Please show us how not knowing the precise value has caused injuries or deaths.

Correct, if the EGC is open, but then this right here claims we shouldn't use those 3 light plug in testers either.

I agree, we should not. Never said we should.

In any case its better to know the EGC is open.

That can be accomplished in any number of simple ways.

Of course.

Do you understand that paragraph you are responding to is about external testers?

Supervisory circuit? If they mean the test resistor, the GFCI pictured has a 10K resistor, (12ma), and further, if the voltage is in the upper limit? Its over 9ma even for a 9ma sized resistor at 120 volts.

:?

And this is where a tester comes in, checking both Live and neutral have opened. :thumbsup: And no, a 3 light tester wouldn't catch a hung up neutral.

That document was written quite a while ago, the newer GFCIs do more supervisory.

http://www.legrand.us/passandseymou...t-gfci/ul-943-gfci-standard.aspx#.VXQrwVKgsrc

And that is just the latest up grade to the standards, there have been other upgrades since that OSHA document was published.

But again, this is just comparing a tester vs an internal resistor. Still doesn't give much info on ma during testing, speed, or successful opening of all contacts.



A tester would tell me:

With an immediate imbalance drop;

Time to trip at 3ma, abort after 6 seconds (just to check for nuisance tripping)


Time to trip at 5ma (abort after 13 seconds)


Time at 10ma

Time at 15ma

Time at 30ma

Time at 50ma


Then we do a ramp test to determine the current rise in relation to the trip time.

Still putting the cart before the horse.

Show the need for all this info, beyond that it looks pretty on a report and gives you the warm fuzzies.

 

[mbrooke]

Yes, that is about an external plug in tester which is not the same as the internal test.

Then answer this:

1. What is the ohms of the test resistor inside a GFCI?

2. Does this resistor pass different current levels relative to line voltage variants?

3. Does the tester not do the same?

There is no need to increase standards requirement when the existing ones are working fine. You have yet to post anything showing that existing standards are causing unsafe conditions.

There was a clear and easily provable need for seatbelts.

Ok, you may have a point here, but the UK's reasoning ought not to be dismissed either. I will let Tony answer.

Sure with external testers.

If you actually read the text it explains that is not the case with the internal test button operation.

Really? Show me.

Above 126.5 volts is a problem in in itself. Do you think all electrical equipment needs to be designed to operate safely far above or below its nominal voltage rating?

I never mentioned above 126.5 volts. IF I have 126 volts at a receptacle in many areas I have no basis to peruse action as its within defined legal bandwidths.

Im sure if I posted a thread arguing 126 was to high at a job site you would then post the POCO and NEMA voltage boundaries saying it was fine.


And no, I never said anything about designing equipment to run outside of standardized bandwidths.

Nice try though.

So again you are looking for absolute safeguarding without showing any evidence it is needed,

Show me the injuries or property damaged caused by GFCIs failing to test properly operating out of their voltage range.




I agree those plug in testers are not a good way to go. Never said they were. I have been saying the internal tester does the job.

Again, never said anything about GFCIs going over the voltage range. My point was under ohms law a GFCI's test resistor running at 126 volts will not pass the same current level as say 109 volts.

So with that said, my point to which I was trying to make, manufacturers purposely choose a lower ohm value for the test resistor inside the GFCI so a line voltage of 100 volts can still trip the GFCI. Down side is 125 volts will pass more current during the test.

Same reason why many tester pass more current then they need to, and to which the article was picking up on.

Not sure how much clearer I can get.

The standards tell us that the internal test is all we need.

Please show us how not knowing the precise value has caused injuries or deaths.

Show me how those standards were derived? I would not mind looking them over myself.


And yes, you are correct, no investigation exist on how many people have been harmed with a working test button but failed other tests.

Do you understand that paragraph you are responding to is about external testers?

Yup! Last I checked ohms law applied to all resistors, including the one inside a GFCI serving its test button.

That document was written quite a while ago, the newer GFCIs do more supervisory.

http://www.legrand.us/passandseymou...t-gfci/ul-943-gfci-standard.aspx#.VXQrwVKgsrc

I know, tell me about :rant: That's what I was referring to. Id say this is an overstep, much like requiring concrete encased studs because some people take the batteries out of their smoke alarms. :happyno:



But, that brings up an excellent point. If IEC based RCDs were used for AFCI protection, a self test feature would not be necessary as no electronics can fail.

And that is just the latest up grade to the standards, there have been other upgrades since that OSHA document was published.

Which are all "price points"

Yes we can debate testing, however continuing to add various bells and whistles like self testing is nothing more than another way to rake in profit without actually addressing the issue at hand. Something manufacturers are beginning to master. :happyno:

 

[don_resqcapt19]

I?m giving up, I?m right in that everything should be tested and recorded and you?re right because there are more of you.

It is just not how things are typically done here. The standards and the codes do not require extensive testing. If testing and documentation is required, it is required by the contract documents and not a code or standard. It would be somewhat rare for the contract documents to require testing and documentation for dwelling units. That is much more commonly found on industrial and larger commercial projects, but not even on all of them.

Now if someone comes up with a logical explanation of why things shouldn?t be tested other than MCB?s I?ll listen. ...

Testing costs money and if the contract documents don't require it, it won't happen.

...Regarding my statement about the RCD exploding, a 125A RCD is a bit unforgiving with an internal short circuit.

Our GFCIs are typically 15 and 20 amp devices with a few up to the 60 amp range.

I?ve done very few domestic installs, it works out at about one every eight years. That is the reason I had another electrician test my flat. I?m authorised to work and test up to 11KV and yet I can?t test a domestic install.

In an lot of areas in the US, there is no license required to do electrical work, and even in some places where a license is required, all you have to do to get the license is pay the fee.