[Sparky0007]

I am the follow up electrician. The first electrician went out of business. I am cleaning up their mistakes.

I have an arc fault breaker which keeps tripping in the master bed room. I tried replacing it with a new one. The new arc fault trips also. I replaced it with a standard breaker and everything works great.

I can only assume after reading further is that there is a short in the new wiring and that the place is going to burn down any minuite. It has been 3 weeks of normal use and everything is good. There is a ceiling fan and fluorescent light in the room. Could the motor or fluorescent lighting be causing this problem? Is there any other solution besides replacing the wire in this case? I am really stumped on this one.

I know my shop vac and cheap table saw can cause my arc fault breaker to trip at home once in a while. Are there certain appliances that just trip arc fault breakers?

[Stratmando]

2 circuits sharing a common neutral will cause tripping. Unplug everything ant try, do certain things cause it to trip?

[donf]

Is this a new installation or an existing site?

Are the conductors copper or aluminum?

According to the 2008 NEC, you must have an Arc Fault breaker for the bedrooms

[Missouri Bound]

Sparky, yes there are... electric motors, fluorescent lights, toasters, and electric heaters all can trip an arc fault breaker. Newer breakers are being perfected now, but again at a higher cost which weed out these "nuisance" trips.

[tkrussell]

To trouble shoot this, need to know, if possible, when the AFCI trips, such as what action happens, what is on, etc.

A switch for the light or fan can be the cause, due to arcing at the contacts.

Try changing out the switches. Try to find a good quality switch. A ceiling fan and CFL light does not normally have arcing involved directy inside them, but are inductive loads, and will cause arcing at the switch.

You could clear all loads and the hot, neutch, and EGC at the panel, test for continuity between the neutch and EGC. An unintentional connecton between neutch and EGC can case the tripping.

Shop vac and table saw has motors that use brushes, brushes always have arcing, so they would cause tripping.

Loose connections, such as caused by whiz wire or stab in the back type connections can cause arcing, so check, even better change, and whiz wire connection to wrap around the screw connection.

[Sparky0007]

2 circuits sharing a common neutral will cause tripping. Unplug everything ant try, do certain things cause it to trip?

That is a great possibility. I wonder if they tied neutral together from 2 different circuits at some point inside the house. It is a new construction. I heard that one guy ran wires and then another guy installed the outlets and switches.

I know 2 circuits sharing a comon neutral would trip a GFI. I did not know that an arc fault would work the same way. It does make sense.

Thanks,

[Sparky0007]

Is this a new installation or an existing site?

Are the conductors copper or aluminum?

According to the 2008 NEC, you must have an Arc Fault breaker for the bedrooms

Conductors are copper in a new construction track of houses.

[Sparky0007]

Sparky, yes there are....electric motors, flourescent lights, toasters, and electric heaters all can trip an arc fault breaker. Newer breakers are being perfected now, but again at a higher cost which weed out these "nuisance" trips.

Thanks for the information. I will try to buy a really expensive one and see if it cures the problem.

Thanks,

[Sparky0007]

To trouble shoot this, need to know, if possible, when the AFCI trips, such as what action happens, what is on, etc.

A switch for the light or fan can be the cause, due to arcing at the contacts.

Try changing out the switches. Try to find a good quality switch. A ceiling fan and CFL light does not normally have arcing involved directy inside them, but are inductive loads, and will cause arcing at the switch.

You could clear all loads and the hot, neutch, and EGC at the panel, test for continuity between the neutch and EGC. An unintentional connecton between neutch and EGC can case the tripping.

Shop vac and table saw has motors that use brushes, brushes always have arcing, so they would cause tripping.

Loose connections, such as caused by whiz wire or stab in the back type connections can cause arcing, so check, even better change, and whiz wire connection to wrap around the screw connection.

The arc fault breaker trips as soon as it is set. I was unable to get inside the first time I went to trouble shoot this one. I know that the fan light combo has a single gang fan/light switch that came with the fan. 27 of the other units have the same fan and switch.

I put an amp meter on it and it read 3.1amps.

I will get in there and wrap the wires around the screws on the recepticals and switches. Someone else suggested that sharing an arc fault neutral can cause this problem. I know it would cause a GFCI to trip but I have not experimented with arc fault breakers enough to know. It does seem like it would trip if it was shared with another circuit.

[Stratmando]

Unplug everything, on the circuit(s), the 2 circuits, and turn off all switches on the 2 circuits, then try to reset. A neutral can not be touching ground as well, or it will trip.
Does this ARC Fault circuit exit the panel with another conductor, sharing the neutral, if so, try turning off that breaker, then reset the ARC fault.

[KISS]

The other choice is to use the ARC faults on the receptacles only and standard breakers on the lighting.

Many/Most of the AFCI's are indeed combo AFCI/GFCI breakers.

[Sparky0007]

Unplug everything, on the circuit(s), the 2 circuits, and turn off all switches on the 2 circuits, then try to reset. a neutral can not be touching ground as well, or it will trip.
Does this ARC Fault circuit exit the panel with another conductor, sharing the neutral, if so, try turning off that breaker, then reset the ARC fault.

Thanks, I will give that a shot.

[Sparky0007]

The other choice is to use the ARC faults on the receptacles only and standard breakers on the lighting.

Many/Most of the AFCI's are indeed combo AFCI/GFCI breakers.

I looked everywhere for an arc fault receptical. As far as I can tell they do not exist. Found an article that explained that the intention of arc fault is to protect the house from burning down from sparking wires in the walls as well as sparking cords.

It was interesting
www.cpsc.gov/CPSCPUB/PUBS/afcifac8.PDF

[Missouri Bound]

I think KISS was suggesting that you should use ARC fault breakers on the receptacle circuits. There are no arc fault recepticals.

[KISS]

True. That's what I was suggesting, but tk says they are required on all outlets and a lamp is an outlet or a place of utilization.

I have another idea: Replace the AFCI with a GFCI and see if the trips occur.

Arcs in switches won't case GFCI's to trip and neither will a load signature that arc faults have.

If it trips with a GFCI, then your probably looking for a grounded neutral, a shared neutral or a leakage condition.

So, you might be able to rule something out.

-or-

Try hanging two lamps from the fan and light circuits with the AFCI to eliminate the ceiling fan.

[Stratmando]

Still don't know if 2 circuits sharing a circuit. If so and additional Neutral is not an option, tie the 2 hots of the multi circuit together and hook to ARC fault load side.