2000 and late - Page 2 - Electrician Talk - Professional Electrical Contractors Forum

brian john · 09-06-2009, 10:34 AM

Quote:

Originally Posted by MDShunk

Beats me. Look at it like this: Since they're now required most places, we have the benefit now of not having spend the intellectual energy to puzzle on whether they do any good or not. We can go 'round and 'round on their possible lack of benefit, but the fact remains that they are here to stay and the requirement is highly unlikely to get removed once it's in place.

Few laws are ever repelled, even bad laws remain on the books for years.

Government grown it does not shrink.

waco · 09-06-2009, 12:32 PM

Quote:

Originally Posted by MDShunk

Beats me. Look at it like this: Since they're now required most places, we have the benefit now of not having spend the intellectual energy to puzzle on whether they do any good or not. We can go 'round and 'round on their possible lack of benefit, but the fact remains that they are here to stay and the requirement is highly unlikely to get removed once it's in place.

Excellent point. I dislike the cost and I dislike having to return to "parsing" circuits to minimize the breakers needed because of the cost, but it looks like they are here to stay.

Oh happy day, big, roomy panels with more spaces than any reasonable house needs, and we're back to crowding the circuits to keep down the costs of the CIDs.

"Nothing changes, but the changes!"

brian john · 09-06-2009, 12:36 PM

What I'd really like to know with AFCI's is.

1. Is there hard core evidence that they work?
field reports are mixed IMO.
2. Was this a money making device fostered by the manufactures or is this a legitimate life saving device?
3. Was this product legitimate but pushed on the market to soon in order to increase revenues?
4. Or the issues being experienced due to a lack of education and understanding on behalf of the electrical trade?

micromind · 09-06-2009, 12:49 PM

The newest version of the code is not necessarily the safest, and is certainly not the most economical.

AFCIs are a good example, where they're required most guys I know (myself included) will put more lights and receptacles on a circuit that before. The homeowner, tired of the breaker tripping, might possibly follow uncle Bobs advice....."Put a 30 in, then it won't trip".

When things are required by law, and they don't work, people in general lose respect for the law. Then they're more inclined to simply violate it. Sometimes to their detriment, sometimes not.

So the 20 amp AFCI is replaced with a regular 30. Indeed, the breaker doesn't trip anymore. Problem solved....or is it?

Rob

manchestersparky · 09-06-2009, 02:30 PM

Quote:

Originally Posted by oldschool

oh i am well aware of that

this is in MD
Montgomery Co
City of Gaithersburg

I thought they were of a different breed.

The City of Gaithersburg has their own AHJ's and rules apart from Montgomery county. The same goes for Rockville City. (Anything inside the city limits is theirs)

Montgomery county is still on the 2002. They have a formal hearing in a little over a week, were the 2008 NEC is being presented to the county council for adoption. If approved as presented ,it then goes to the county executive to be signed into law.
Then it will be decided how to phase it in.
Hopefully this should all be completed by years end.
(The 2008 is being presented as written)

Oldschool : what are you working on in Gaithersburg ?

oldschool · 09-06-2009, 03:38 PM

Quote:

Originally Posted by manchestersparky

The City of Gaithersburg has their own AHJ's and rules apart from Montgomery county. The same goes for Rockville City. (Anything inside the city limits is theirs)

Montgomery county is still on the 2002. They have a formal hearing in a little over a week, were the 2008 NEC is being presented to the county council for adoption. If approved as presented ,it then goes to the county executive to be signed into law.
Then it will be decided how to phase it in.
Hopefully this should all be completed by years end.
(The 2008 is being presented as written)

Oldschool : what are you working on in Gaithersburg ?

Two additions, one in the Kentlands and one in Lakelands. Both in the city limits.
I knew Mont Co was 2002, but i wasnt sure of Gaithersburg, since i havent done any work there in quite a while. I was thinking of shelving my license in the city until these two jobs came up.

waco · 09-06-2009, 09:54 PM

Do AFCIs work? As far as I know, which isn't very far, there is no way to test them since none of the theories (I've read) seem clear on how they are supposed to work. I mean, arcs (as I recall from my calibration days) have components in the radio frequency ranges. I know I was making up a switch on a new lighting circuit with a brand new AFCI in the panel. The circuit was hot and the switch was "on" so the connection was arcing as I made it. Breaker didn't trip, but I guess maybe such an arc doesn't have the right "signature." I don't know.

Sure seems to me any place wired to the latest code is going to pretty much eliminate the need for extension cords whose failures (according to one AHJ) is the main reason we now have AFCIs.

Oh well. Had a customer complain because the breaker in his new Seimans tripped when the old breaker in his old FPE panel didn't when his daughter was using all her curling irons and blow driers.

"Yes, I think that was the point of swapping out the panel, wasn't it?"

"Oh, yeah."

MDShunk · 09-06-2009, 10:46 PM

Quote:

Originally Posted by waco

Do AFCIs work? As far as I know, which isn't very far, there is no way to test them since none of the theories (I've read) seem clear on how they are supposed to work. I mean, arcs (as I recall from my calibration days) have components in the radio frequency ranges. I know I was making up a switch on a new lighting circuit with a brand new AFCI in the panel. The circuit was hot and the switch was "on" so the connection was arcing as I made it. Breaker didn't trip, but I guess maybe such an arc doesn't have the right "signature." I don't know.

If I remember rightly, the test involved placing a #12 in the middle of a wad of spun cotton fiber and chopping it with a paper cutter. I wish I could remember where I saw that. It was a white paper with lots of pictures. I'm kicking myself now for not downloading and saving it.

micromind · 09-07-2009, 12:04 AM

When AFCIs were first required, there was a lot of controversy as to whether they actually worked or not. They were advertised to 'detect the characteristics of an electrical arc.' Being an experimenter by nature, as well as a certifiable lunatic, I decided to run a test of my own.

I installed an AFCI in a panel, and connected a couple of #12s to the breaker, and put a cord cap on the wires.

Next, I stripped about 4" of insulation off of a cheap #18 or 16 two-wire household extension cord. With the breaker on, and the strands of wire not touching each other, I plugged the cord in. Then I jiggled the cord so that the fine strands of wire would touch each other.

There were lots of sparks, lots of loud pops, some smoke, blue-white flashes, etc.

The AFCI absolutely failed to detect the characteristics of an actual electrical arc.

There's no question in my mind that the aforementioned arc easily could have started a fire.

To test the breaker, I shoved what remained of the stripped end of the cord onto a metal tabletop. The breaker tripped quickly. Not a lot of arcing this time.

The obvious conclusion here is that they don't do what they're advertised to. At least this one didn't. They might be better now, this was a few years ago.

From what I can gather, an AFCI is nothing more than a standard breaker with a 75 amp magnetic trip unit, and a 30 ma GFI. No magic circuitry that sees the actual characteristics of an electrical arc.

There are relays that can accurately detect an electrical arc, trip a breaker, and even tell how far away the arc was. They cost about $3500 (so I hear), and are normally found in POCO meterhouses and switchyards. I really don't think you could cram all that electronic wizardry into a 120 volt branch circuit breaker though.

Rob

brian john · 09-07-2009, 09:10 AM

Quote:

Originally Posted by micromind

. I really don't think you could cram all that electronic wizardry into a 120 volt branch circuit breaker though.

Rob

Do not bet on what you can cram into a device the size of a CB, ever look at all a Itouch can do?

BadSplice · 09-07-2009, 11:41 AM

Quote:

Originally Posted by brian john

Do not bet on what you can cram into a device the size of a CB, ever look at all a Itouch can do?

My iPhone does even more!!!

However, that is mostly software based. For what he is talking about, you'd need to cram a lot of hardware into a small space.

brian john · 09-07-2009, 12:45 PM

Quote:

Originally Posted by BadSplice

My iPhone does even more!!!

However, that is mostly software based. For what he is talking about, you'd need to cram a lot of hardware into a small space.

Not really, the old protective relays we test on switchboards use to take up a space 48"X90" the new electronic relays take 6"x12". ONe relay takes the place of numerous devices.

drsparky · 09-07-2009, 01:14 PM

Quote:

Originally Posted by micromind

When AFCIs were first required, there was a lot of controversy as to whether they actually worked or not. They were advertised to 'detect the characteristics of an electrical arc.' Being an experimenter by nature, as well as a certifiable lunatic, I decided to run a test of my own.

I installed an AFCI in a panel, and connected a couple of #12s to the breaker, and put a cord cap on the wires.

Next, I stripped about 4" of insulation off of a cheap #18 or 16 two-wire household extension cord. With the breaker on, and the strands of wire not touching each other, I plugged the cord in. Then I jiggled the cord so that the fine strands of wire would touch each other.

There were lots of sparks, lots of loud pops, some smoke, blue-white flashes, etc.

The AFCI absolutely failed to detect the characteristics of an actual electrical arc.

There's no question in my mind that the aforementioned arc easily could have started a fire.

To test the breaker, I shoved what remained of the stripped end of the cord onto a metal tabletop. The breaker tripped quickly. Not a lot of arcing this time.

The obvious conclusion here is that they don't do what they're advertised to. At least this one didn't. They might be better now, this was a few years ago.

From what I can gather, an AFCI is nothing more than a standard breaker with a 75 amp magnetic trip unit, and a 30 ma GFI. No magic circuitry that sees the actual characteristics of an electrical arc.

There are relays that can accurately detect an electrical arc, trip a breaker, and even tell how far away the arc was. They cost about $3500 (so I hear), and are normally found in POCO meterhouses and switchyards. I really don't think you could cram all that electronic wizardry into a 120 volt branch circuit breaker though.

Rob

America needs more mad scientists like Rob.