What is the purpose of 15 amp breakers (excluding motor loads)

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cppoly

Senior Member
Location
New York
Is there a purpose to using 15 amp breakers (excluding motor loads) for general circuiting if you are using #12 wiring?
 

dkidd

Senior Member
Location
here
Occupation
PE
Not unless there is a reason like voltage drop.

What would you think motors are different?

Usually motors have a smaller wire and larger OCPD.

Small motors can be limited to the smallest overcurrent device available. I don't have the reference on the top of my head.
 

dkidd

Senior Member
Location
here
Occupation
PE
Is there a purpose to using 15 amp breakers (excluding motor loads) for general circuiting if you are using #12 wiring?

Not for general circuiting. Specific motors and equipment is all that I can think of.
 

JFletcher

Senior Member
Location
Williamsburg, VA
Is there a purpose to using 15 amp breakers (excluding motor loads) for general circuiting if you are using #12 wiring?

If you were in New York City, possibly elsewhere in NY, number 14 wire is not allowed. The prints may spec a 15A circuit, so you wind up with number 12 and a 15 amp breaker.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Thanks. So it's safe to say using 15 amp breakers with #12 wire for general circuiting has no real purpose.

It used to be a pretty common spec that wire pulled in conduit had to be at least #12. This was for physical strength reasons becasue it was felt that #14 was more likely to be damaged while being pulled. I don't know if it was true but I have seen this in a ton of specs over the years. But, I have not seen it in the last decade. I think the drive to reduce costs won over.
 

tom baker

First Chief Moderator
Staff member
1. I use #14 for instrumentation circuits to flowmeters, sensors, where there is a small load, and most have limited space in the wiring terminal areas
2. For rewires on dwelling units, I use #14 for lighting, especially with small cut in boxes, where box fill is an issue
 

jap

Senior Member
Occupation
Electrician
Is there a purpose to using 15 amp breakers (excluding motor loads) for general circuiting if you are using #12 wiring?

Yes.

To make the guy that comes along behind you look like a hero when he throws his 20 amp breaker on your nuisance tripping 15 amp circuit.

JAP>
 

jumper

Senior Member
Um, NYC specs a minimum of #12 for all GP circuits so 20A OCPDs are the norm but one could put #12 on a 15A breaker. Barring any real tangible reason like VD, it is a silly rule IMO.

Edit: just saw Fletch’ s post, yes that is a nyc spec.
 

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
House remodel I have seen #14 spliced to #12 and zip cord in walls; someone could have just said "I'll put a 15 on it and call it good". Did you see it done or just inquiry?
 
Maybe there is a mix of 12 and 14 on the circuit? Depending in where you get it, 14 mc can often actually cost more than 12. Maybe someone thought they would do everything in 12, but had a change of heart when they got to 3 ways and smoke detectors ;)
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
NYC #12 minimum, been in the code for about 100 years. Until about 20 years ago all general purpose and non-277 volt lighting circuits were limited to 15 amps.
 
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