Extending 12/2 Romex

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Alwayslearningelec

Senior Member
Location
NJ
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Estimator
Have 12/2 romex run to a particular location that was never used( microwave). Now the microwave is now in a new location so we have to extend the circuit. The microwave only requires 15A's. Can I splice 14/2 to 12/2? Thanks.
 

tthh

Senior Member
Location
Denver
Occupation
Retired Engineer
Seems like a bad idea to change out the breaker on #12 to 15A. Someone in the future might not know there is a wire gauge change and put it back to a 20A breaker. But, it can all be avoided by using #12 - if you can fish 14/2 to extend the circuit, you can fish 12/2 instead.
 

infinity

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Location
New Jersey
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Journeyman Electrician
Seems like a bad idea to change out the breaker on #12 to 15A. Someone in the future might not know there is a wire gauge change and put it back to a 20A breaker. But, it can all be avoided by using #12 - if you can fish 14/2 to extend the circuit, you can fish 12/2 instead.
You could always put a note on the wire stating that part of the circuit is #14 AWG but that isn't required. Personally I wouldn't bother.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Seems like a bad idea to change out the breaker on #12 to 15A. Someone in the future might not know there is a wire gauge change and put it back to a 20A breaker. But, it can all be avoided by using #12 - if you can fish 14/2 to extend the circuit, you can fish 12/2 instead.
While the #14 would be compliant with a 15a breaker, I must agree with this post.
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
Where is this microwave? Most common locations have requirements for 20A circuits (e.g. kitchen counters, over the range hood) even though I've never seen a kitchen item with a 20A plug. If you are pulling new wire, I think it is short sighted to change to a smaller size as 12 should be just as easy as 14 to pull.
 

kwired

Electron manager
Location
NE Nebraska
You could always put a note on the wire stating that part of the circuit is #14 AWG but that isn't required. Personally I wouldn't bother.
agree. may be ok design decision but is not a requirement.

Any time I see "oversized" conductor on a particular OCPD, I kind of figure there is a good reason even if it isn't obvious.
 

Another C10

Electrical Contractor 1987 - present
Location
Southern Cal
Occupation
Electrician NEC 2020
Now the microwave is now in a new location so we have to extend the circuit. The microwave only requires 15A's. Can I splice 14/2 to 12/2?
Many don't seem to agree with my input but here it goes, First of all stick with the same wire size because its fool proof and will keep you out of trouble.

technically the #14 rating is roughly 1850w, if never exceeded it would be safe, until someone decides to continue out of that box with additional loads which can happen, they'd now have a 2400w rated breaker allowing for an 1850w rated conductor to provide more service.

Not mentioned but as, if not more of a concern, the extended splice still needs to be accessible, don't be like the jack of all trade master of none handyman and bury the splice in the wall or behind a new cabinet.

The wiring will only utilize what the load requires.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
To each his own. I would put #12 on a 15 amp OCPD everyday without a second thought. To me this is no different than converting a 240 volt, 30 amp electric dryer circuit to a 120 volt, 20 amp for a gas dryer and putting the #10's on a 20 amp OCPD.
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
Whether code compliant or not, I'm going to say I've seen way to many instances on either repair or remodel and find 20A breaker starting off with 12awg and someone transitioned to 14awg that was hidden out of view that was definitely older than the 20A breaker installation. So someone saw the 12awg and decided they could put a 20A breaker in when the panel change was done not knowing of the changed wire site somewhere in the middle between receptacle outlets.
 

roger

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Location
Fl
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Retired Electrician
To each his own. I would put #12 on a 15 amp OCPD everyday without a second thought. To me this is no different than converting a 240 volt, 30 amp electric dryer circuit to a 120 volt, 20 amp for a gas dryer and putting the #10's on a 20 amp OCPD.
Funny, I just did the same thing three days ago putting a #6 on a 20 amp breaker for someone changing an electric range to gas.

Roger
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Whether code compliant or not, I'm going to say I've seen way to many instances on either repair or remodel and find 20A breaker starting off with 12awg and someone transitioned to 14awg that was hidden out of view that was definitely older than the 20A breaker installation. So someone saw the 12awg and decided they could put a 20A breaker in when the panel change was done not knowing of the changed wire site somewhere in the middle between receptacle outlets.
This is where the electrician should earn his pay and verify what's on the circuit. If it's a DIYer, we can't stop it from happening and shouldn't loose sleep over it. The fact of the matter is a #14 conductor can handle well over 20 amps and wouldn't be a real problem anyways.

Roger
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Funny, I just did the same thing three days ago putting a #6 on a 20 amp breaker for someone changing an electric range to gas.

Roger
You are probably going to hell especially since the equipment grounding conductor has not been upsized proportionally with the other conductors. Shame on you....hahaha
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Funny, I just did the same thing three days ago putting a #6 on a 20 amp breaker for someone changing an electric range to gas.

Roger

This is one of the few situations where I think an adapter makes more sense than changing the circuit. By using the adapter the high amperage circuit remains available for a future dual electric/gas appliance.

Regarding the original post, I agree the if a 15A circuit is kosher, then it is ok to extend a 12ga circuit with 14ga and then use a 15A breaker. I wonder, however, if there is a chance that this might be considered a small appliance branch circuit even though it is intended to be dedicated to the microwave.

Jon
 
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