champion
Member
- Location
- St. Louis Missouri, US
I will try to make this as short as possible.
I added a new 120v 20amp branch circuit to a small 100 square foot room added to an existing dwelling. The 20amp circuit is protected with a Murray Arc fault breaker labelled "circuit breaker and branch feeder". The 20amp branch circuit feeds 4 duplex receptacle outlets and 4 recess can lights. The line side of the circuit from the Arc fault breaker terminates first in a 1 gang switch box that controls the lighting. From this 1 gang box, the circuit was extended to the 4 receptacle outlets in the new addition. The Receptacles are not switched.
The customer contacted me and indicated that when he plugged in his shop vacum, the breaker tripped as soon as he turned it on. He reset the breaker and tried it again, and it ran for awhile and tripped again. He also indicated that he tried using another power tool and the breaker tripped again.
I went to the home and duplicated what the customer indicated he was doing and I had the same trouble.
I verified the connection to be correct in the service panel for the AFCI connection.
I isolated the hot, neutral and equipment ground connections on the branch circuit and found no connection or continuity betweem these leads. I did the same for the lighting section of the branch circuit also and found all leads to the lighting and receptacles clean of any shorts or connections between current carrying conductors and equipment grounds.
I purchased another 20amp Murry AFCI of the same type from the same distributor and tried the circuit again.
I got the same results.
After this, I proceeded to check the equipment that the customer was using for ground falults and found none.
Next, I took a current reading on the circuit when it was funtioning with the shop vacum and lighting on and the current reading was about 12amps.
I then proceeded to change the AFCI temporarily with a Seimens combination AFCI rated 15amps and retried the equipment again.
The circuit was functioning just fine and no longer tripped with the Seimens AFCI.
Is there something going on here that I need to learn or know regarding these Arc Fault breakers---such as a difference between the combination arc fault and the circuit breaker & branch circuit arc fault?
or---did I just have some very bad luck in purchasing some defective arc faults from a particular distributor out of the same mfg batch?
When should I use a combination type and when should I use a feeder type.
PS--The Murray AFCI breaker only tripped when the lighting was switched to the on position while the shop vacum was running--and --again while lights were on turning on the vacum switch.
The light bulbs installed in the recess cans are of the incandescent type.
Thank you in advance for any light on this subject.
Jim--perplexed
I added a new 120v 20amp branch circuit to a small 100 square foot room added to an existing dwelling. The 20amp circuit is protected with a Murray Arc fault breaker labelled "circuit breaker and branch feeder". The 20amp branch circuit feeds 4 duplex receptacle outlets and 4 recess can lights. The line side of the circuit from the Arc fault breaker terminates first in a 1 gang switch box that controls the lighting. From this 1 gang box, the circuit was extended to the 4 receptacle outlets in the new addition. The Receptacles are not switched.
The customer contacted me and indicated that when he plugged in his shop vacum, the breaker tripped as soon as he turned it on. He reset the breaker and tried it again, and it ran for awhile and tripped again. He also indicated that he tried using another power tool and the breaker tripped again.
I went to the home and duplicated what the customer indicated he was doing and I had the same trouble.
I verified the connection to be correct in the service panel for the AFCI connection.
I isolated the hot, neutral and equipment ground connections on the branch circuit and found no connection or continuity betweem these leads. I did the same for the lighting section of the branch circuit also and found all leads to the lighting and receptacles clean of any shorts or connections between current carrying conductors and equipment grounds.
I purchased another 20amp Murry AFCI of the same type from the same distributor and tried the circuit again.
I got the same results.
After this, I proceeded to check the equipment that the customer was using for ground falults and found none.
Next, I took a current reading on the circuit when it was funtioning with the shop vacum and lighting on and the current reading was about 12amps.
I then proceeded to change the AFCI temporarily with a Seimens combination AFCI rated 15amps and retried the equipment again.
The circuit was functioning just fine and no longer tripped with the Seimens AFCI.
Is there something going on here that I need to learn or know regarding these Arc Fault breakers---such as a difference between the combination arc fault and the circuit breaker & branch circuit arc fault?
or---did I just have some very bad luck in purchasing some defective arc faults from a particular distributor out of the same mfg batch?
When should I use a combination type and when should I use a feeder type.
PS--The Murray AFCI breaker only tripped when the lighting was switched to the on position while the shop vacum was running--and --again while lights were on turning on the vacum switch.
The light bulbs installed in the recess cans are of the incandescent type.
Thank you in advance for any light on this subject.
Jim--perplexed
