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#98254 - 05/18/06 01:51 PM AFCI Questions  
kyelectric  Offline
Joined: Aug 2005
Posts: 64
I am having some troube out of an AFCI installed on a house I recently finished. I know they nuicense trip sometimes but what would I look for to cause it to trip. It may go for days without tripping and then just trip for no apparent reason. The fire alarms, bedroom light w/fan and 1 outside light right outside the door are on this AFI.

Is there a reason that the inspector told me you can only install 15 amp AFI's for the bedrooms or was this just his preference. I pulled the 20's out and replaced them with 15's but I cannot find in the code book anywhere that prohibits 20 amp AFCI's in bedrooms. They make'em and sell'em everyday!

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#98255 - 05/18/06 02:40 PM Re: AFCI Questions  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,142
I would look at the ceiling box with the fan and be sure there was no bare wire showing on that neutral wirenut. The guys at the IAEI meetings say that is the #1 cause.

Greg Fretwell

#98256 - 05/18/06 10:56 PM Re: AFCI Questions  
Celtic  Offline
Joined: Feb 2005
Posts: 361
I cannot find in the code book anywhere that prohibits 20 amp AFCI's in bedrooms

And you won't.

See: 210.12(B)

~~ CELTIC ~~
...-= NJ =-...

#98257 - 05/19/06 07:44 AM Re: AFCI Questions  
Reel-Break  Offline
Joined: Apr 2002
Posts: 178
Most of the time we find grounding wire touching neutral at receptical somewhere.I also just recently had a smoke detector that was the culprit.We always wire the bed rooms in a certain way just for trouble shooting purposes. I mean I always go from master bed light sw to smoke. From a certain rec to feed light sw. that way you come back and know exactly where to disconnect this part from that part.For example I can go right in and disconnect my recepticals from my smokes and fan lights.It helps.

#98258 - 05/19/06 06:19 PM Re: AFCI Questions  
renosteinke  Offline
Cat Servant
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
It is also quite possible that some appliance is fooling the AFCI into thinking there is a problem. Electronic dimmers, variable speed motors, electronic fluorescent ballasts, and surge protectors have been know to cause such nuisance trips.

#98259 - 05/19/06 07:15 PM Re: AFCI Questions  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,142
I didn't think about dimmers but I bet if this dimmer is tripping an AFCI it would make an AM radio painful to listen to.
There are some old "non-RF friendly" dimmers that put nasty stuff back into the power line.
IBM's dirty little secret was the "noise" everyone had their panties in a wad about in the computer room came from phase control power supplies (in our machines) that were not unlike a cheap dimmer.
They basically just chopped 3VDC or 5VDC straight off of the 208v phases with SCRs and used a big bank of capacitors to turn it into usable DC. When you looked at these spiky wave forms on a scope it was hard to believe it used to be sine waves.

Greg Fretwell

#98260 - 05/20/06 10:53 PM Re: AFCI Questions  
Gregtaylor  Offline
Joined: Mar 2005
Posts: 212
Boise, Idaho, USA
One other scenario is that the customers never tell you everything. Do they unplug the vacuum cleaner or iron or other small appliance under load? That's all it takes and the AFCI is mysteriously tripped. When you go to the house these things are no longer plugged in. Ask 'em.

#98261 - 05/21/06 12:46 AM Re: AFCI Questions  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,142
Wouldn't that be a series arc?
I didn't think an AFCI could see them.

How much oil is in this snake?

Greg Fretwell

#98262 - 05/21/06 03:41 AM Re: AFCI Questions  
macmikeman  Offline
Joined: Jul 2002
Posts: 717
Honolulu, Hawaii
Its the ground wire touching neutral. Betcha betcha.

#98263 - 05/21/06 08:49 AM Re: AFCI Questions  
festus  Offline
Joined: Nov 2003
Posts: 40
fairfax Va USA
All the homes I wired up use 14 gauge wire for bedroom lighting circuits because of cost. 14 gauge = 15 amp breakers. Now, if the home were wired with 12 gauge throughout, 20 amp would be acceptable.How many people want to spend the extra money for the increase?

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