AFCI and 2 wire circuits

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eddycurrents

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Will an AFCI breaker work on a 2 wire circuit (no equipment grounding conductor)? One electrician tried to tell me how they would not work on a 2 wire circuit and he was bragging how he told an inspector that wanted them installed, how they wouldnt work and he didnt know what he was talking about. Turns out the inspector beleived him and said he didnt need to put them in after all. Now wouldnt the breaker still detect a series arc on the hot or grounded conductor, or a short circuit? Thanks.

[ February 12, 2004, 03:53 PM: Message edited by: eddycurrents ]
 
Re: AFCI and 2 wire circuits

An AFCI will work on the 2-wire circut.
It will detect parallel arcs but not series arcs.
Even Cutler Hammer who's literature stated that their AFCI breakers would detect series arcs, have changed their stance and now their literature states that series arcs can not be detected.
 
Re: AFCI and 2 wire circuits

Hi Todd. I thought that they would detect series arcs, but not all of them. I am led to beleive that not all series arcs are supposed to be detected, such as the closure of a switch.

Am I mistaken, or is there a small amount of series arc protection in these devices?
 
Re: AFCI and 2 wire circuits

In my opinion the effectiveness of an AFCI installed on a circuit that does not include an EGC is significantly reduced. It appears that the vast majority of faults are detected and cleared by the ground fault circuit and not the arc detection circuit. At some point a series fault on most wiring systems will progress to a parallel fault that the AFCI can detect, but this may be too late to prevent a fire.
I'm not sure why the installation of AFCI protection would be required by the code for a 2 wire circuit.
Don
 
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