AFCI Breakers

[growler]

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:

One thing to consider is that we have a different market here in the US than say the UK. The self test can be very important here because our rules are much different. Here in most jurisdictions a homeowner can purchase and install a GFCI receptacle or breaker and perform the needed test even without the aid of an electrician.

Actually in many areas a person can obtain a permit and build their own home to include the electrical (some areas like for the service to be connected by a licensed electrician).

A homeowner or home inspector can go around and test every GFCI device in a house in a matter of minutes.

Where I think the safety record is better in the UK is they require testing even in older homes. Here we don't require anything unless the power is shut off for a certain amount of time (6 mo-1 yr.) or if a permit is needed for additional work.

It comes down to "do you want freedom or safety" and the two are usually not the same.

 

[growler]

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

Thinking of all the testing done in the UK and that they are keeping a labor intensive system makes me think they must have a stronger union (more political power) to keep workers from being replaced by technology.

The same manufacturers operate on both sides of the pond so any technology we have they also have.

I know we are not to mention the "U' word but I'm not taking sides only useing it as a possible explanation for a different system.

 

[kwired]

Regarding the test button:
I?ve had the resistor burn out or even more fun, short circuit. The damn thing exploded.

I?m sorry, I can?t understand how pressing a test button constitutes a ?test?, far too many possibilities for variance.

The test performed by the test button is not a thorough test that checks if the device still meets all specifications, but is a good indicator whether the majority of it's functions are working at all, and is mostly intended to be a test for the end user to perform periodically, if the device doesn't trip when the user does perform such test then that is a sign something is likley wrong and that a professional should be consulted or at very least replace the device with same component type. They are supposed to meet all design standards out of the box, if they didn't what is the point of the listing process or even other consumer goods types of standards they likely must meet? JMO.

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~

On AFCI's that is a good question I haven't found an answer for. At least with the GFCI many of us know what the device is looking for and do know that the test button introduces a real condition that should trip it and that the GFCI is basically looking for just one condition, the only thing in question is whether it really repsonds to correct current levels?

The AFCI is supposedly going to respond to many possible conditions - how does one button assure us of the many possible fault conditions? You need to understand the firmware of the device to even have a clue on this, most of us don't but the manufacturers and others involved just want us to trust they are doing the right thing.

 

[GoldDigger]

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~

The only way possible: It assumes that if the microprocessor is running it will be executing the correct program and then activates a dedicated test input on the microprocessor. I do not know whether there is any to use the microprocessor to test the signal input components, but it will certainly be able to test the microprocessor driven trip components.

An very sophisticated external tester could actually generate an arc signature or a set of arc signatures. But there is no way to build that into the device.

I would agree that to a large extent the TEST button on an AFCI does not do as complete a test as the TEST button on a GFCI.

 

[romex jockey]

Gentlemen,

with all due respect to your responses , how am i suppose to peddle this product with a clear conscious ?

~RJ~

 

[mbrooke]

One thing to consider is that we have a different market here in the US than say the UK. The self test can be very important here because our rules are much different. Here in most jurisdictions a homeowner can purchase and install a GFCI receptacle or breaker and perform the needed test even without the aid of an electrician.

Testing GFCIs is just a hypothetical consideration, we don't have to apply it hear. We can however take a UK style 30 or 50ma RCD with no electronics and us it as a submain breaker applying AFCI protection. By our standards the test button will do. However having no electronics in theory we would not need to worry about a lack of self testing circuitry.

Actually in many areas a person can obtain a permit and build their own home to include the electrical (some areas like for the service to be connected by a licensed electrician).

A homeowner or home inspector can go around and test every GFCI device in a house in a matter of minutes.

It is speeder. Ok, for the sake of this thread I will say the test button is sufficient :thumbsup:

Where I think the safety record is better in the UK is they require testing even in older homes. Here we don't require anything unless the power is shut off for a certain amount of time (6 mo-1 yr.) or if a permit is needed for additional work.

It comes down to "do you want freedom or safety" and the two are usually not the same.

Pushing aside testing requirements for the sake of the argument, I think we can have both.


My biggest point in all these posts are that AFCI protection could have been achieved at 1/12 the cost with more reliability and no nuisance tripping. That is the point I am trying to make.

 

[mbrooke]

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.

Pushing all other testing aside, if code required an IR test for all new dwellings, AFCIs could in theory have been left out of the code. In fact the first thing most sparkies now do is IR for tripping AFCIs. They do reveal wiring errors.

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

But we can always mass produce a sub main 60amp GFP for arc fault protection. GFCIs might still be needed since 5ma is better than 30 or 50ma, but it still come out cheaper for arc faults.

 

[ELA]

Rather old data now but still relavent on AFCI test button

Rather old data now but still relavent on AFCI test button

Here is an examination of what at least one manufacturers test button does,
http://forums.mikeholt.com/showthread.php?t=111163

 

[don_resqcapt19]

Pushing all other testing aside, if code required an IR test for all new dwellings, AFCIs could in theory have been left out of the code. In fact the first thing most sparkies now do is IR for tripping AFCIs. They do reveal wiring errors.

I don't agree. It is my opinion that very very few of the faults that can cause a fire would be detected by an IR test. The vast majority of fires are caused by high connections with a high resistance. Almost all of the wring errors that the AFCIs have revealed have been neutral to ground faults, and those types of faults are not likely to cause a fire.

 

[iwire]

Pushing all other testing aside, if code required an IR test for all new dwellings, AFCIs could in theory have been left out of the code. In fact the first thing most sparkies now do is IR for tripping AFCIs. They do reveal wiring errors.

Do you really mean IR testing as in infrared thermography?

I am trained in IR and I can't see any way IR would be helpful in that situation.

I suspect you mean insulation resistance testing.

 

[mbrooke]

I don't agree. It is my opinion that very very few of the faults that can cause a fire would be detected by an IR test. The vast majority of fires are caused by high connections with a high resistance. Almost all of the wring errors that the AFCIs have revealed have been neutral to ground faults, and those types of faults are not likely to cause a fire.

I agree, imo 90-95% of all fires are caused by glowing connections. However, the AFCI claim is that some of these fires are caused by over driven staples/damaged insulation. An insulation resistance test can catch these conditions caused during initial installation.

Do you really mean IR testing as in infrared thermography?

I am trained in IR and I can't see any way IR would be helpful in that situation.

I suspect you mean insulation resistance testing.

My mistake, insulation resistance testing via mega-ohm insulation test meter.

 

[don_resqcapt19]

... However, the AFCI claim is that some of these fires are caused by over driven staples/damaged insulation. An insulation resistance test can catch these conditions caused during initial installation. ...

That was one of the original reasons used to support the need for AFCIs, but the November, 2012 UL report titled "Investigation of Damage and Degradation on Breakdown Voltage of NM Cables" suggests that a over driven staple or hammer damage to the NM cable is not very likely to result in a fire.

 

[mbrooke]

That was one of the original reasons used to support the need for AFCIs, but the November, 2012 UL report titled "Investigation of Damage and Degradation on Breakdown Voltage of NM Cables" suggests that a over driven staple or hammer damage to the NM cable is not very likely to result in a fire.

BINGO!

But an IR can catch a hot touching a nail or staple.

 

[iwire]

BINGO!

But an IR can catch a hot touching a nail or staple.

Not IR.

 

[mbrooke]

Not IR.

you know what I mean by IR :thumbsup:


Insulation resistance test.

 

[romex jockey]

The international views here are interesting.

A Multi-test meter that ramps up?

Detailed electrical reports on some 3 yr cycle?

RCD's.....? Main & sub RCD's ?.....dual {earth & neutral} protectants?

Earthing systems other that our TNSC , which would be banned elsewhere??




So just how much of a recluse am I here?

How much of this rock subscribes to the NEC/CEC vs. the IEC ?

~RJ~

 

[kwired]

BINGO!

But an IR can catch a hot touching a nail or staple.

If the nail or staple is driven into wood framing it will depend on the resistance of the wood. If it is higher moisture wood - you may see it on the test all depends on conductivity to your other test probe, if it is very dry wood it could be a better insulator then the plastic insulation on the conductors and you never see it.

 

[mbrooke]

If the nail or staple is driven into wood framing it will depend on the resistance of the wood. If it is higher moisture wood - you may see it on the test all depends on conductivity to your other test probe, if it is very dry wood it could be a better insulator then the plastic insulation on the conductors and you never see it.

Perhaps, but I would think further testing would need to confirm. My understanding is most chemically treated wood has a lower resistance?

 

[iwire]

If the nail or staple is driven into wood framing it will depend on the resistance of the wood. If it is higher moisture wood - you may see it on the test all depends on conductivity to your other test probe, if it is very dry wood it could be a better insulator then the plastic insulation on the conductors and you never see it.

If you can't pick it up with a mega I doubt it will be a problem in the future.

I do agree with mbrooke that insulation testing when a job is compleate could catch a lot of things. Without the need for AFCIs.

 

[kwired]

Perhaps, but I would think further testing would need to confirm. My understanding is most chemically treated wood has a lower resistance?

Do they use anything in regular construction lumber for treatment? There is treated lumber but it is not normlly used for general construction in locations expected to remain dry. Maybe a sill plate on a concrete foundation at times but the rest of the wall will be non treated.