Exhaust fan

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hhsting

Senior Member
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Glen bunie, md, us
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Junior plan reviewer
I have two exhaust fans in restrooms, two inline exhaust fans in duct all four on 120V single phase fed from one branch circuit. The branch circuit is 0.39kVA which equals 3.25A.

One inline is model Cook GN520 and second inline is model Cook GN320. The two restroom exhaust fans are Cook GC240, GC220.

The branch circuit breaker provided is 20A. When asked for 15A breaker instead of 20A breaker because load draws 3.25A, I was told that the breaker protects the branch circuit cable not the fan or it’s motors and #12 AWG size cable is provided so 15A breaker would not be provided.

However, I researched but I cannot find the above in code NEC 2014 that branch breaker protects the cable not the fans. Anyone know where it would be for four exhaust fans or the breaker needs to be sized 15A?
 
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Hv&Lv

Senior Member
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Engineer/Technician
That makes no sense.
You can protect 4/0 copper with a 15 amp breaker if you want.

you can’t use 14 awg and put a 20 amp breaker on it.
 

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
That makes no sense.
You can protect 4/0 copper with a 15 amp breaker if you want.

you can’t use 14 awg and put a 20 amp breaker on it.

Don’t follow. Cable provided is #12 AWG on 20A breaker but four fans draw 3.25A. So 15A breaker was asked but was told breaker protects the cable not the fans. Does it matter if breaker is sized 15A or 20A?
 

Hv&Lv

Senior Member
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Occupation
Engineer/Technician
No.
The point is the wire can be bigger, just not smaller.
I have an electrician buddy I work with that wired his house with #10 wire for his outlets, and used 20 amp breakers on it.
He won’t ever do that again. Said it was like wrestling a bear to terminate the wire on the outlets.
 

Eddie702

Licensed Electrician
Location
Western Massachusetts
Occupation
Electrician
15 or 20 a breaker is ok. I would opt for the 15 if it were me. Assuming the fan motors have thermal protection.
That makes no sense.
You can protect 4/0 copper with a 15 amp breaker if you want.

you can’t use 14 awg and put a 20 amp breaker on it.
you can if it's a motor circuit
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
However, I researched but I cannot find the above in code NEC 2014 that branch breaker protects the cable not the fans. Anyone know where it would be for four exhaust fans or the breaker needs to be sized 15A?
See 430.53(A) for the allowance to put the fans on a 20A breaker.
 

RRJ

Senior Member
Location
atlanta georgia
Occupation
Electrician
Some builders don’t allow you to install 15 amp breakers on comercial settings!


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