Shared Neutral Circuit

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gouger32

Member
I was just sent to a resturant because the breaker was tripping on the exhaust fan circuit. There are 2 fans on the same circuit. The feed is a 12 wire, but the neutral is shared with another circuit. The 2 fans draw 8.9 amps when running, but after a few minutes the breaker trips. The breaker will not trip if the fan on the left is running by itself. As soon as the fan on the right is turned on it trips a few minutes later. Here is the kicker. We just replaced the fan on the right, and it still does the same thing! New breaker also. Any Ideas???? Thanks
 

ultramegabob

Senior Member
Location
Indiana
what kind of fans are these? do you leave the ammeter on to see if the amperage rises? if amperage doesnt rise, it sounds like you have an intermittant short, could be to either neutral or ground, you may need to megger your wires to check the insulation....
 

gouger32

Member
The breaker trips if the right fan only runs. If the left side fan is on by itself the breaker does not trip. I am going to try to run a wire from the left side fan to the right side fan, and switch them together. Im hopeing that the switch leg to the right side fan is bad. Do you think that the shared neutral circuit could be a problem?? also the amperage stays the same even when it trips. I ohmed out the wires and they were good so maybe the insulation is bad. Thank you very much.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
This is not a MWBC from what you said. Both fans on the same circuit. The neutral is not the problem. You either have another bad fan or most probably a bad wire going to the fan.
 
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