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keila0311 · Jun 17, 2009, 08:47 PM

So we just had our house rewired. The bedroom is on a dedicated AFCI 15 amp breaker. We have two ceiling lights and about 5-6 outlets on the circuit. I wired all the outlets and the lights. Everything was tested and tested fine. However, when I put a compact fluorescent light bulb in one of the light fixtures it trips the breaker. We do not have anything else plugged in at this time. The light switch does not trip the breaker until there is a light bulb in the fixture. I replaced the fixtures thinking this was it but it doesn't work. Any suggestions?

donf · Jun 18, 2009, 07:11 AM

Can you take a few pictures of the wiring for the light switch for us?

keila0311 · Jun 18, 2009, 07:27 AM

Originally Posted by donf

Can you take a few pictures of the wiring for the light switch for us?

Probably not. However it is your standard lught switch. Three wires in box, neutrals wire nutted together, two hots connected to the brass screws on the switch, extra hot is wire nutted to another hot so onlg two hots are exposed. Like I said the light switch does not switch teip the breaker until we put a light bulb in the circuit. It is wired with 12-2 wire.

donf · Jun 18, 2009, 10:32 AM

Okay, we are going to need your eyes to figure this out. From your description, once the circuit is completed (by installing the bulb and activating the switch, the breaker trips). This suggests to me a dead short.

I need to know the following:

Where is the power for the light coming from. Is it coming from the switch leg? Our in the ceiling outlet is there a main line that supplies a switch loop.

I also need a very accurate description of how the switch is wired and exactly where on the switches each wire is connected.

ballengerb1 · Jun 18, 2009, 10:38 AM

Don, dead short or arc fault?

donf · Jun 18, 2009, 10:57 AM

Dead short. If it was arching or sparking, I would expect the poster to tell us of the odor of melting plastic or of burn marks on either fixture or switches. So I suspect a misrouted wire.

What are your thoughts?

ballengerb1 · Jun 18, 2009, 11:02 AM

I have had some difficulty with homes when I connected a AFCI. Due to how some homes were wired, or later jury rigged, the same neutral was used for more than one circuit and this trips the AFCi.

donf · Jun 18, 2009, 01:42 PM

Exactly! I wouldn't be surprised if the Neutrals that are tied together at the switch has one that should be part of the switch loop and not an actual neutral.

Digital pictures would really help, but so be it.

tkrussell · Jun 18, 2009, 01:46 PM

Could be just a defective switch. The arcing in a switch can be picked up by an AFCI breaker.

I do not think it is a short, as the CB trips only when a lamp in the fixture, if I understand the first post correctly.

jerro · Jun 18, 2009, 02:00 PM

Put a regular incandescent bulb in and see if that trips the breaker.

tkrussell · Jun 18, 2009, 02:04 PM

Good idea:

Originally Posted by jerro

Put a regular incandescent bulb in and see if that trips the breaker.

However the switch may still be defective while the AFCI breaker does not trip, as a CFL lamp is an inductive load as opposed to a resistive load of an incandescent lamp.

Maybe, maybe not, just saying.

donf · Jun 18, 2009, 02:50 PM

TK,

Looking back at the original item, I noted that the Keila wired the entire room by herself and then tested the room.

The failure only occurs when a CF bulb is inserted into the ceiling fixture and the switch is flipped. Makes absolute sense. Prior to the bulb being inserted both the switch and the missing bulb cause the circuit to be open.

I wonder, if the switch was left in the "Open" (Off) position would anything else in the room actually work.

Keila, would you mind plugging in a protable radio in each of the outlets and verifying that they actually work.

Also, please test the second light in the room to make sure it works with the switch to the first light in the OFF position.

keila0311 · Jun 18, 2009, 10:08 PM

Originally Posted by tkrussell

Could be just a defective switch. The arcing in a switch can be picked up by an AFCI breaker.I do not think it is a short, as the CB trips only when a lamp in the the fixture, if I understand the first post correctly.

It had to have been a faulty breaker. Replaced it and all works! Thanks all for suggestions,