A problem given to me by anothr inspector.He recently encountered a problem with an arc fault that wouldn't hold. The project was a remodel due to a fire, but basically the house was completely rewired. The has tried several other breakers, but they also trip when even a minimal load (radio) is introduced. I understand from the wholesaler that they are so senitive that even an insulated staple will cause the breaker to trip if the staple is to tight.Is that a common occurrence? Are other inspectors requiring that a load be put on the circuit to test the arc fault breakers before covering the walls. What can you advise me to help this other inspector.
arc faults
- Thread starter gimpyfac
- Start date
- Status
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: arc faults
An AFCI has to be tested with a load, 100 watt lamp is OK. As the AFCI contains an 30 mA or so GFCI (not a class a GFCI) the load will detect any inadvertant neutral to ground connections. I suspect that most of the problems with AFCI's are from miswires/crossed wires, similar to when GFCI's were first introducted it may liars out of some installers....
Another suggestion would be to get an AFCI tester.
An AFCI has to be tested with a load, 100 watt lamp is OK. As the AFCI contains an 30 mA or so GFCI (not a class a GFCI) the load will detect any inadvertant neutral to ground connections. I suspect that most of the problems with AFCI's are from miswires/crossed wires, similar to when GFCI's were first introducted it may liars out of some installers....
Another suggestion would be to get an AFCI tester.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: arc faults
Gimpy the problem that you discribed is a common one. any time that you have a AFCI that trips when a load is applyed it because of a connection between the ground and a grounded conductor (neutral) this is because theAFCI has a current coil in it just like a GFCI the senseing circuit is set a little higher though as it is set to 30-50ma. when there is no load the current coil wont see a imbalance between the hot and neutral, but when a load is applyed then the hot will have more current on it than the neutral this is because the neutral/ground connection will share the current and this will leave the neutral with having less current than the hot. this causes a current to form in the coil and is picked up as a ground fault and the electronics open the breaker. this can also be caused by a shared neutral too. but staples are not the cause as if this is happening to AFCI's then it will be happening to non-AFCI circuit only the breaker wont trip but you will still have a dangerous neutral to ground connection that can give someone a bad shock. remember there has to be a connection between the ground and neutral for this to happen. if this is being caused by staples then someone is driving them to hard. the most common cause is the bare ground wire touching the neutral screw in a receptacle box. and the best way to stop that is to run all the screws in and be more careful when installing the device as to push the grounds back in the box as you put the device in. we need to teach others on how these devices work so they can understand what can cause problems so it can be watched for on the installs.
Gimpy the problem that you discribed is a common one. any time that you have a AFCI that trips when a load is applyed it because of a connection between the ground and a grounded conductor (neutral) this is because theAFCI has a current coil in it just like a GFCI the senseing circuit is set a little higher though as it is set to 30-50ma. when there is no load the current coil wont see a imbalance between the hot and neutral, but when a load is applyed then the hot will have more current on it than the neutral this is because the neutral/ground connection will share the current and this will leave the neutral with having less current than the hot. this causes a current to form in the coil and is picked up as a ground fault and the electronics open the breaker. this can also be caused by a shared neutral too. but staples are not the cause as if this is happening to AFCI's then it will be happening to non-AFCI circuit only the breaker wont trip but you will still have a dangerous neutral to ground connection that can give someone a bad shock. remember there has to be a connection between the ground and neutral for this to happen. if this is being caused by staples then someone is driving them to hard. the most common cause is the bare ground wire touching the neutral screw in a receptacle box. and the best way to stop that is to run all the screws in and be more careful when installing the device as to push the grounds back in the box as you put the device in. we need to teach others on how these devices work so they can understand what can cause problems so it can be watched for on the installs.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: arc faults
Sorry Tom didn't see where you had already said about the neutral to ground connection but I do get carried away with explaining.
Sorry Tom didn't see where you had already said about the neutral to ground connection but I do get carried away with explaining.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: arc faults
P.S. The reason a GFCI trips immediately on a ground to neutral fault is it is set to trip at 5-7 ma. and at this level there will almost always be enough stray current on the grounds that will cause this. and if it is high enough it will immediately trip a AFCI too.
[ June 11, 2003, 12:28 AM: Message edited by: hurk27 ]
P.S. The reason a GFCI trips immediately on a ground to neutral fault is it is set to trip at 5-7 ma. and at this level there will almost always be enough stray current on the grounds that will cause this. and if it is high enough it will immediately trip a AFCI too.
[ June 11, 2003, 12:28 AM: Message edited by: hurk27 ]
- Status