AFCI Breaker Nuisance Tripping

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emce

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We are the designers for a housing project in a military compound. Design included the use of AFCI breakers for outlets in the bedrooms as required in the NEC. We have recently been notified that occupants of the home have been complaining of nuisance tripping in the AFCi breakers. Whatever they plug in to the outlet causes the breaker to trip. We have heard from associates in Hawaii that they are having similar problems. They particularly mentioned that motor loads, more specifically electric fans, cause the breakers to trip. We would like to know what other types of loads people have noticed to cause tripping of AFCI breakers. In this case, breakers are GE.

Another question is whether 15A GE AFCI breakers could be the cause of the problem. The breakesrs have recently been changed to 20A and several instances of tripping have stopped. However, there are still cases of tripping with 20A breakers.

Any help would be appreciated. thanks.
 
Re: AFCI Breaker Nuisance Tripping

Interesting symptoms.
Whatever they plug in to the outlet causes the breaker to trip.
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This, simply, sounds like the neutral and the equipment ground are reversed.
motor loads, more specifically electric fans, cause the breakers to trip.
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This one is hard to attribute to a cause, without further detail.

What are the wiring methods in the housing? Conduit, NMB? Same method in your project and in Hawaii? What is the workmanship of the installers like, if you know?
 
Re: AFCI Breaker Nuisance Tripping

Or more commonly when you push back an outlet into position it is not uncommon for that bare grounding wire to fold up along the side of the neutral screw and touch up against the neutral. If that happens the neutral current will be shared by the grounding conductor and the AFCI will interpret it a ground fault and trip.
 
Re: AFCI Breaker Nuisance Tripping

My sentiments exactly .afci`s are sentitive to neutral to ground faults and will hold until a load is present open trim plates and look for bare grounds near neutral screws,some installers leave bare wire when back stabbing 14 ga. and that is where it occurs.Can`t tell you how many times I have removed face plates and had to remove devices to find the fault :eek: Just a question would an ideal vol/com selinoid tester have enough ma to trip an afci if there was an grnd/neut. fault :D
 
Re: AFCI Breaker Nuisance Tripping

The breakesrs have recently been changed to 20A and several instances of tripping have stopped.
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I hope the branch circuit wiring was rated for 20 amps. :confused:
 
Re: AFCI Breaker Nuisance Tripping

Make sure the neutral of the branch circuit is landed on the AFCI breaker and not the neutral bar, and the neutral is not being shared with another circuit as in a multiwire circuit. If you can place a resistive load like a small heater on the circuit and it trips the neutral is the problem, but if it only trips with a motor load when it is shut off it is a transient problem and could be that a surge suppressor is plugged in the same circuit.
 
Re: AFCI Breaker Nuisance Tripping

The breakers have recently been changed to 20A and several instances of tripping have stopped. However, there are still cases of tripping with 20A breakers.
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Mmmmm, There is no difference between the 15a and 20a breakers AFCI sensitivity so both should have responded the same to whatever was causing the 15a AFCI to trip if in fact it was tripping as a result of the AFCI sensing circuit.
If the 15a AFCI was in fact malfunctioning then replacing with another would have provided the same result as the 20a AFCI which goes back to his statement
However, there are still cases of tripping with 20A breakers.
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Unless..... the breaker was responding to an overload where a 15a breaker would trip and the 20a, being higher, wouldn't which I personally don't think is the case at all. But, logic would dictate that if the problem didn't involve the AFCI sensing circuit then the overload/short circuit elements would be the only other cause.
 
Re: AFCI Breaker Nuisance Tripping

Originally posted by templdl:
But, logic would dictate that if the problem didn't involve the AFCI sensing circuit then the overload/short circuit elements would be the only other cause.
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Those two words are seldom found in the same sentence! :D

One nice feature of Siemens is that they have a little flag that displays when the AFCI circuitry interrupts the circuit. Can be helpful when troubleshooting a problem like this.

[ March 09, 2005, 10:57 PM: Message edited by: georgestolz ]
 
Re: AFCI Breaker Nuisance Tripping

Any AFCI, GFCI circuit has to be run through the process of elimination to find what is causing the tripping. The first place I would start is turn off the breaker then check for current with an amp prob. if none then remove the neutral and hot from the breaker. Check continuity between the neutral and the grounding bar where the grounding conductor of this circuit is still connected. If there is continuity then remove the grounding conductor and check again. if there is still continuity then there is a connection to another circuit. if the continuity was opened when the grounding conductor was removed then there is a connection between the neutral and grounding conductor of this circuit, If the hot wire that was landed on the AFCI breaker comes out of a jacket (NM) which also has a red conductor that is terminated on another breaker, then the circuit is a multiwire circuit which will require a two-pole AFCI or another circuit ran. If the wires comes out of a conduit with one neutral and two hots see above for (NM).

We can guess all day as to why but in the end it will be the diagnostics that find the truth
 
Re: AFCI Breaker Nuisance Tripping

George, Interesting point that you brought up on the siemens AFCI. An excellent feature.
This is certainly not to meant as preaching to the choir. But when we think about it the common TM breaker can trip because of an overload (thermally)or short circuit (magnetically.) Now we have the challenge of have two choices, Overload or short circuit which often is hard enough. Unless you are there when the breaker trips and the breaker not allowed time enough to cool down, it can be difficult to troubleshoot. A breaker that trips thermally will not be able to be reset and closed immediately where a breaker that trips magnetically can. At least we have some direction. Now throw in either GFCI or AFCI. Is it an overload, short circuit, GF, or AF?
That "flag" that you pointed out goes a long way in giving some direction for us to take when resolving a tripping problem.
As hurk27 said that 'we can guess all day' which is what often happens.
 
Re: AFCI Breaker Nuisance Tripping

Thanks everyone for your help. We have a scheduled visit today to see one of the homes where tripping of the AFCI breakers is occurring. We'll look into several items and will post our findings.

Thanks again.
 
Re: AFCI Breaker Nuisance Tripping

Has anyone had any issues with computers in the bedroom tripping the AFCI when the computer is initially booted up? I have heard this from several people using various brands so it does not sound like an issue with the wiring techniques.
 
Re: AFCI Breaker Nuisance Tripping

Not computers but new vacums have been the reason for service calls.Go there and circuit is fine plug in the brand new vacum and it trips the breaker.What i tell the H/O`R is put it on a non afci circuit and use it that way and try it again in a bedroom.New armature new brushes not seated they dont really understand it but haven`t had a call back yet :D
 
Re: AFCI Breaker Nuisance Tripping

One problem is that when a load is turned off the resulting transient voltage forces a phantom ground fault to flow through the wiring capacitance to ground. There is nothing wrong other than the interaction of circuit capacitance and inductance. Same goes for when the starting switch on a split phase motor opens.

Series woulnd motors are also bad news because they generate a high frequency noise voltage and current that flows right through the insulation capacitance to ground.
 
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