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arc fault breaker not tripping when wires are burnt in bedroom

Posted by fsimo63 (My Page) on
Thu, Jul 21, 11 at 22:06

I purchased a new home and the lights would flicker in the two upstairs bedrooms when we used an iron. Thinking that the problem may be with the iron we plugged it into other rooms in the house to test this theory and the lights didn't flicker in those rooms.
We contacted the home builder and they sent an electrician out to check it out. I showed them what I described above. The electrician didn't take the light fixtures down to check them, he said that with the arc fault breakers this was normal.
I decided to install a ceiling fan in one of the bedrooms upstairs and when I removed the ceiling light fixture I noticed the wires and wire nuts were burnt and melted. I decided to check the other bedroom upstairs also and found the same problem.
I checked the breaker box and found that both upstairs bedrooms are wired to one 15Amp AFCI. I counted the # of switches in each room and found a total of 4 light switches and 15 electrical outlets wired to the one breaker.
I contacted the home builder again and they sent an electrician out that didn't seem to know much about it and said it was beyond his knowledge and would let the builder know to send out a troubleshooter.
Four weeks later we have still not seen anyone to troubleshoot and when calling the builder they said they would replace the ceiling light fixtures.
Any suggestions on what would cause these problems and how to resolve this?


Follow-Up Postings:

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RE: arc fault breaker not tripping when wires are burnt in bedroo

"when I removed the ceiling light fixture I noticed the wires and wire nuts were burnt and melted."

Larger than allowed bulbs will do the same thing.
If an arc was occurring the AFCI should have tripped.

The iron may be a large enough load to cause momentary dimming when the heating element turns on.
Heating elements pull more power when they are cold.

"I counted the # of switches in each room and found a total of 4 light switches and 15 electrical outlets wired to the one breaker."

There is actually no limit on the number of outlets on a residential circuit.
The 180 V-A per receptacle is for commercial work.


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RE: arc fault breaker not tripping when wires are burnt in bedroo

If the wire nuts were melted, the iron certainly isn't your problem.

That particular junction that melted was creating heat - and lots of it. Not everything that creates heat will trip an AFCI - and your iron is a good example. The AFCI is measuring current wave forms and comparing it to "normal" waveforms (like turning on a light or plugging something into an outlet.) If the wave form exceeds the normal in speed and intensity, it trips the breaker.

The thing that causes heat is a combination of current and resistance. That could be in the form of the resistance of air (as in an arc) or gunk. Or it could be from higher current flowing through a wire that wasn't designed to handle it (as in a bulb too big for a fixture.)

Also, ACFI's break. Have they checked to see if it is actually working?


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RE: arc fault breaker not tripping when wires are burnt in bedroo

Do you live in a Ball Home in Kentucky? Sounds like it...I had the same problem! I rewired everything!


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RE: arc fault breaker not tripping when wires are burnt in bedroo

It takes an arc to trip the AFCI. You can have poorly made connections that will heat up that don't arc nor trip the regular overcurrent. Someday some engineer will figure out a way to detect this and the NFPA will cram "Hot-Wire-Nut detecting" breakers down our throats.

As for now, this is the reason these are required to be made inside boxes.


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RE: arc fault breaker not tripping when wires are burnt in bedroo

Since this is a newly-built home with original wiring, would you please share with us THE NAME OF THE BUILDER/FIRM involved?

It would be a huge public service. Thanks in advance.


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RE: arc fault breaker not tripping when wires are burnt in bedroo

Don't plug the iron into a 15 amp bedroom circuit. Use the 20 amp laundry circuit instead. With everything else turned on, you may be overheating the bedroom circuit with the iron. It's the "scotch lock" type of connectors that are the first to show overheating.


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RE: arc fault breaker not tripping when wires are burnt in bedroo

Who said anything about Scotchloks? The poster said wire nuts and really there are two possibilities. There were either installed improperly and hence made a higher resistance connection that heated up OR as brick pointed out, it could have just been the heat of the fixture that caused it.


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