15amp breakers for general purpose in a dwelling?

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JWalker23

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First off, the project in question is located in the bay areas suburb of Pittsburg, CA. It is my understanding per the NEC that 20 amp breakers are required for the small appliance branch circuits, laundry branch circuits, and bathroom branch circuits. Bedrooms requires 20 amp arc-fault breakers. My question is, for other circuit types not noted above (general receptacles, general lighting, etc) am I still allowed to use 15 amp breakers and #14 Romex? I dont see anything in the NEC but I wanted to make sure.
 
Welcome to the forum.:)

Strictly from the NEC the bedroom AFCI circuits can be 15 amp on #14 NM cable. Also the NEC permits #14 NM on 15 amp breakers for most circuits in a dwelling unit other than the aforementioned bathroom, laundry, and small appliance branch circuits.

Chris
 
drone46 said:
First off, the project in question is located in the bay areas suburb of Pittsburg, CA. It is my understanding per the NEC that 20 amp breakers are required for the small appliance branch circuits, laundry branch circuits, and bathroom branch circuits. Bedrooms requires 20 amp arc-fault breakers. My question is, for other circuit types not noted above (general receptacles, general lighting, etc) am I still allowed to use 15 amp breakers and #14 Romex? I dont see anything in the NEC but I wanted to make sure.
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There is nothing in the NEC that requires bedrooms to be on a 20 amp branch circuit... sounds like a local ordinance.

As far as the "rest of the house" if the jurisdiction has specific requirements for bedrooms then they may very well have something more on the books. I would double check or ask the AHJ before proceeding.

Pete
 
I have never understood why a building official would want to adopt a code to require a higher rating of a circuit then what is allowed per NEC?

heres how I feel, with the many cheap cords and wiring in appliances we get these days, and the fact that many older appliances are still in use, and cords that unknowingly get replaced on appliances can be a hazard when plugged into circuits with a higher rating, I have seen Christmas lights with very small wire I.E. 22 awg or smaller that have no chance to trip a 20 amp circuit, but would a 15 amp circuit, so why in the world would they make a code to only allow 20 amp circuits, what are they thinking?

I have had home owners want all 20 amp circuits in a house, and after I tell them there increasing the possibility of having a fire with using older appliances with possible bad cords and or using these cheap Christmas lights that come from over seas, they change their mind real quick, I guess after a neighbor who had a fire because his cat chewed into the cord from his lights on his Christmas tree and the wire just glowed red hot instead of tripping the 20 amp breaker that it was plugged into, I changed my thinking, before this I was one who thought bigger was better.

I know that most equipment today is required to have at the minimum 20 AWG cords, which will trip a 20 amp breaker on a bolted fault, but add any resistance or voltage drop to the circuit such as an extension cord and you could just get to a point a 20 amp breaker wont open, and sure the same could be true with a 15 amp breaker, but I think I would rather have the 15 amp breaker to at least lessen the possibility?

I'm glad that here our state followed this reasoning also when it was suggested to require all circuits to be 20 amps in a house.

so for me its 15 amps for any general purpose receptacles, more breakers/circuits if they want, but not 20 amp circuits.
 
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acrwc10 said:
Interesting point of view.
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Well I have be accused of thinking out of the box a time or two:grin:

We know that most house fires are not cause by the permanent wiring inside of walls, as most are caused by things that get plugged in, I would be willing to bet if records were made of these fires that most would have been on 20 amp circuits, back in the 40's thru the 60's it wasn't uncommon to have whole houses wired in 12 awg, mater of fact around here most older houses that I run into with older tinned copper wiring are all #12 with many having fuse panel with 20 amp or 30 amp fuses installed, of the few of these type houses I did have the chance to see after a fire is was cause by what the occupant had plugged in. and again in a couple I was able to determine it was a cord or appliance cord that over heated that caused the fire, now can I say that if a 15 amp fuse would have prevented the fire, maybe not, but I do think it would have had less of a chance since the fault would have been more likely to have opened a 15 amp then a 20?

I believe that the 20 amp circuit requirements of some areas were based on the over fusing of circuit problems in the past, but today need to be rethought.
 
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A short circuit will trip a 15a breaker just as fast as a 20a breaker. Side-by-side, they're equal when it comes to opening when they're shorted out.

A 15a breaker does not open as soon as the current reaches 15.00000000001 amps, nor will a 20a breaker opens as soon as the current reaches 20.00000000001 amps.

Look at the trip curves of the two, and they're 99.98% identical. The only difference is if the load is between 15 and 20 amps, a 15a breaker will eventually open, while a 20a never will.

If you have, say, a 50-amp load, certainly the 15 will open slightly faster than the 20. But in real life, how often does that happen?
 
Type of fault matters??

Type of fault matters??

hurk27 said:
Well I have be accused of thinking out of the box a time or two:grin:
now can I say that if a 15 amp fuse would have prevented the fire, maybe not, but I do think it would have had less of a chance since the fault would have been more likely to have opened a 15 amp then a 20?
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Wouldn't the type of fault have some bearing on whether a 15 or 20A breaker would trip at all? IIRC back when i was a pup I was told that on some high resistance faults a standard type breaker would never see it as a problem and just keep supplying power as if there was nothing wrong until it was to late and the .99 cent extention cord had burnt through and you actually had a short. Or was I misinformed?
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jsharvey said:
Wouldn't the type of fault have some bearing on whether a 15 or 20A breaker would trip at all? IIRC back when i was a pup I was told that on some high resistance faults a standard type breaker would never see it as a problem and just keep supplying power as if there was nothing wrong until it was to late and the .99 cent extention cord had burnt through and you actually had a short. Or was I misinformed?
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If the fault has a high enough resistance, then the current draw will be low enough to keep it under the trip rating of the breaker. So the breaker will simply see it as another load.

Incandescent lamp filaments are a good example of this.
 
480sparky said:
A short circuit will trip a 15a breaker just as fast as a 20a breaker. Side-by-side, they're equal when it comes to opening when they're shorted out.

A 15a breaker does not open as soon as the current reaches 15.00000000001 amps, nor will a 20a breaker opens as soon as the current reaches 20.00000000001 amps.

Look at the trip curves of the two, and they're 99.98% identical. The only difference is if the load is between 15 and 20 amps, a 15a breaker will eventually open, while a 20a never will.

If you have, say, a 50-amp load, certainly the 15 will open slightly faster than the 20. But in real life, how often does that happen?
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True enough, but what if that extension cord with 22 gage wire is overloaded to, say 22 amps? And homeowners will do this. I don't have any trip curves in front of me at the moment, but I would guess that the 15 amp breaker would trip significantly faster.
 
eprice said:
True enough, but what if that extension cord with 22 gage wire is overloaded to, say 22 amps? And homeowners will do this. I don't have any trip curves in front of me at the moment, but I would guess that the 15 amp breaker would trip significantly faster.
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How does a breaker know the size of conductors that are on the circuit?
 
hurk27 said:
because the little breaker man comes out of the breaker and mesures the wire size goes back in and sets his trip point then goes back to bed (well until a short happens and his house is on fire):roll:
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I understand that part but how does he see in the dark if panel cover is on ? What if he TRIPS.
 
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