afci

[enrique santiago]

hi
i just installed a new afci to feed the receptacles in a bedroom, i ran new wire and i know this was done correctly.....the afci tripped when the tenant connected the vacuum.... my question is: can the vac make the brkr trip or is it just a bad breaker??? i don't want to buy a afci tester, can you guys suggest something???

 

[gregoryelectricinc]

Re: afci

I had this happen in a new home once. I found out that my guys had back-wired all the recepts. I made them go back and pigtail out each box as well as terminate wires to screws and the problem went away. Good arguement for filling t hose stupid back-wire holes in huh?

 

[don_resqcapt19]

Re: afci

Most common reason for an AFCI to trip is a ground wire touching a neutral wire on the load side of the AFCI.
Don

 

[hurk27]

Re: afci

Good anser Don as we now require all our guys to run in unused screws on all devices as this is the biggest cause that little pesky ground wire will always seem to find those backed out screws.
Must be a murphy's law thing. :roll:

 

[tom baker]

Re: afci

Hurk and Don, its interesting as we get further into the AFCI requirements the tips that are developed....I agree with Don most of the AFCI trips are from inadvertant neutral to ground connections.

 

[renosteinke]

Re: afci

Does anyone know if those pricey AFCI testers do anything that the breaker's test button doesn't do?

 

[hurk27]

Re: afci

Yep makes your wallet even lighter. :roll:

 

[smalljobs]

Re: afci

Why not tape the receptacles and switches ? This should keep the ground wire from touching any screws!

 

[Guest]

Re: afci

Originally posted by gregoryelectricinc:
<snip>I found out that my guys had back-wired all the recepts. I made them go back and pigtail out each box as well as terminate wires to screws and the problem went away. <snip>

I did electrical service work for a year in 1994 and most of the 1970's homes are back-wiring (back-stabbing) arc failures. I cannot believe that UL, the NFPA, and the NEC allow back wiring. Here is a piece I wrote about arcing and backstabbing:

Back-stabbing (back-wiring) causes arc faults and arc fires.

 

[tom baker]

Re: afci

AFCI testers simulate a 75 amp arc fault, most also test GFCI's. I have an Ideal model for evaluation, it does voltage drop, AFCI and GFCI tests. On the GFCI it tells the trip time and current. The breakers button only tests the trip circuitry on the AFCI.

 

[iceman2610]

Re: afci

Hurk and Don. I believe you are thinking of GFCI's when you mentioned that the tripping is usually caused by neutral to ground. I have never had a neutral to ground short trip an AFCI. I have ran into an instance where another electrician had barrowed a neutral from another circuit (Rewire job) and the phase conflict on the neutral would trip the AFCI.

 

[hurk27]

Re: afci

Iceman
No we know that a GFCI will trip any time a ground wire touches a neutral. But AFCI's have the very same coil circuit in them that a GFCI does but it is at a higher setting as a GFCI is set to trip at 5ma of leakage to ground but a AFCI is set to 30-50ma
What this does is when a GFCI's load neutral goes to ground it's more sencitive so it will imedlety trip. But since a AFCI's set at 30-50ma it will almost take a load on the circuit to trip it this is when you go into the bedroom and switch on the light and the AFCI trips. This is because the load caused a imbalance accross the coil that encircles the hot and neutral because some of the neutrl current went back to the source through the ground wire, but with out the load the 30ma setting doesent cause it to trip.
You can test this incase you have any doubt's just touch any load side neutral to the ground first without any load then turn somthing on it might take more than one light and or paddle fan to get it to trip but it will.

 

[hurk27]

Re: afci

P.S.
Just one more thing this will happen also if you have a load connected to the load side hot but the neutral going to the load is comming from the line side (like grabbing the wrong neutral in a box) this will cause the same imbalance to accure and trip eather one. (GFCI or AFCI)

 

[bthielen]

Re: afci

I had a similar experience with a GFCI receptacle. I had used a GFCI in an outdoor receptacle then continued the circuit to supply basement lighting. I used the GFCI to protect the entire circuit. After completing the circuit, when we turned on the basement lights the GFCI would trip. While double-checking my wiring I found that I had a loose connection in one of the wirenuts on some grounded wires in one of my lighting fixtures. I tightened the connection and the problem went away. The only explanation I have is that the loose wirenut connection allow for some arcing and the surge created tripped the GFCI. Any other ideas?

Bob