12/3 connected to 12/2 and 14/2

[deans]

Greetings,

I would like to confirm that, according to the NEC, there is no reason why you cannot use 12/3 connected to 15 and 20 amp breakers (one on pole A the other on pole B) and then (say 30 feet away) branch into two circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on 12/2).

Thank you for your time and energy,
William

 

[Noozer]

Greetings,

I would like to confirm that, according to the NEC, there is no reason why you cannot use 12/3 connected to 15 and 20 amp breakers (one on pole A the other on pole B) and then (say 30 feet away) branch into two circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on 12/2).

Definately WRONG.

You cannot use 14 anything on a 20 amp breaker in any case.

 

[deans]

Dear Noozer,

Thank you for taking the time to answer but please first take the time to read the post.

Thanks,
William

 

[BobK207]

William-

Noozer did his best to answer your question.

Personally I was not able to understand it clearly enough to answer it.

So unless you are willing to restate your original question more clearly I sincerely doubt you will get a better answer.

:"I would like to confirm that, according to the NEC, there is no reason why you cannot use 12/3 connected to 15 and 20 amp breakers (one on pole A the other on pole B) and then (say 30 feet away) branch into two circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on 12/2).

So does this mean you're:

running 12/3 from a 15 amp breaker
& also running 12/3 from a different 20 amp breaker

or have you created a shared neutral situation?

???

and then ~30ft away "branch" (branch what or which; each original circuit ?)

into two two circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on 12/2)

is each original circuit be branched or just one of them? do you intend to install the proper sized breakers to protect the 14/2?

bottom is 12/2 ok on 20 amp breaker, 14/2 is only ok when protected by a 15 amp breaker

fyi when you're asking for free advice try not to piss of the guys with the answers.

why the mixed breaker & wire size?

Just run it all in 12/3 & simplify your life.

cheers
Bob

 

[RBM]

You absolutely cannot do that. Any person working in your panel would have no way to know that the 12 awg had been reduced somewhere downstream and in doing a service upgrade for example would install the wire to a 20 amp breaker

 

[SQLit]

Greetings,

I would like to confirm that, according to the NEC, there is no reason why you cannot use 12/3 connected to 15 and 20 amp breakers (one on pole A the other on pole B) and then (say 30 feet away) branch into two circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on 12/2).

Thank you for your time and energy,
William

I know of no code section that prohibits you from reducing the size of a breaker on a given conductor.

As others said in the future there is a greater chance of someone installing a oversized breaker for the smaller wiring. I would not do what your suggesting.

 

[Toller]

You absolutely cannot do that. Any person working in your panel would have no way to know that the 12 awg had been reduced somewhere downstream and in doing a service upgrade for example would install the wire to a 20 amp breaker

Actually, code specifically allows it. 210.3 "where conductors of higher ampacity are used for any reason, the ampere rating or setting of the specified overcurrent device shall determine the circuit rating". This is frequently done where there is a long run from the breaker box to the first outlet and there might be a voltage drop problem.

But unless you have a good reason to do it, it probably is best to be consistent.

 

[BocesLib]

I would say that could be done, a bit confusing though. No real cost savings in it either.

One thing that would be a problem with it though is if you used arc faults to protect run in bedroom areas (gfci maybe too?) Their neutrals go into the breaker and then to the busbar. No way of sharing it.

 

[deans]

Greetings,

I have attempted to add clarity with the description below:

In the breaker box I have two single pole breakers.
One breaker is 15 amps.
One breaker is 20 amps.
The 15 amp is on pole A.
The 20 amp is on pole B.
There is a 30 ft piece of 12-3 attached to these breakers. (*creating shared neutral situation) The 15 amp is attached to the red wire. The 20 amp is attached to the black wire. At the other end of the 12-3 there is a utility box. In this utility box the red and white wires have been attached to a piece of 14-2. In this utility box the black and white wires have been attached to a piece of 12-2.
Is this a code violation?

Thank you very much,
William

Some responses to specific questions asked as follows:
Q: why the mixed breaker & wire size?
A: to reduce voltage drop to < 5%. The portion of the run already in 14-2 is buried UF and would be a REAL pain to change.

Q: Any person working in your panel would have
no way to know that the 12 awg had been reduced somewhere downstream
A: They would suspect/know because it was attached to a 15 amp breaker

 

[deans]

Greetings,

I am not using AFCI or GFCI circuit breakers in either case.

Thank you,
William

PS: The cost savings come from using wire which is already run instead of having to run new wire in difficult places.

 

[Chris Lewis]

I would like to confirm that, according to the NEC, there is no reason why you cannot use 12/3 connected to 15 and 20 amp breakers (one on pole A the other on pole B) and then (say 30 feet away) branch into two circuits (a 15 amp circuit on 14/2 and a 20 amp circuit on 12/2).

[Your other posting made it clear that the 14/2 is on the 15A side, and the 12/2 on the 20A side, and the common neutral is 12ga as it needs to be.]

AFAIK, according to NEC rules this isn't illegal.

In CEC rules, the 12/3 in a box/shared neutral means that the breakers must be tied. You can't get a 15A/20A pair, tied or otherwise. You can tiebar singles, but that's frowned upon.

However, why bother? You're saving a few pennies at the expense of possible future confusion, and some risk (from untied breakers). By the time you factor in overshoot in having to buy two kinds of wire versus one, and a dual 20A versus singleton 15A and 20A breakers, chances are your approach costs you _more_.

I'd personally use a dual-tied 20A breaker (even if, strictly speaking, you don't have to), and 12ga throughout.

 

[zxcvbob]

Greetings,

I have attempted to add clarity with the description below:

In the breaker box I have two single pole breakers.
One breaker is 15 amps.
One breaker is 20 amps.
The 15 amp is on pole A.
The 20 amp is on pole B.
There is a 30 ft piece of 12-3 attached to these breakers. (*creating shared neutral situation) The 15 amp is attached to the red wire. The 20 amp is attached to the black wire. At the other end of the 12-3 there is a utility box. In this utility box the red and white wires have been attached to a piece of 14-2. In this utility box the black and white wires have been attached to a piece of 12-2.
Is this a code violation?

Thank you very much,
William

Some responses to specific questions asked as follows:
Q: why the mixed breaker & wire size?
A: to reduce voltage drop to < 5%. The portion of the run already in 14-2 is buried UF and would be a REAL pain to change.

Q: Any person working in your panel would have
no way to know that the 12 awg had been reduced somewhere downstream
A: They would suspect/know because it was attached to a 15 amp breaker

You're worrying about it too much. What you have is legal and reasonably safe. It would be better if the breaker handles were tied together, or if you used a 2-pole common-trip 15A breaker instead of a 15 and a 20 (of course not knowing the load you have on the 20A side, a 15A breaker might not be enough)

Best regards,
Bob

 

[deans]

Based on what I hear I am going with it (unless I hear different from someone who can site what code I am violating.)

The 20A load is for a bathroom / laundry room and is required to be 20A by code (or else I would have to run another 20A circuit). The 20A breaker is a standard sized breaker the 15A breaker is a mini-breaker so I am not sure I could even purchase a tie bar if I wanted to.

Thank you all very much.

 

[sleepdog]

Doesn't the NEC specify that a single, dedicated 20A circuit is required for the washer/dryer receptacle? Or you already have that in place and are running another 20A circuit for the bath portion?

 

[deans]

There are 5 circuits in the bathroom / laundry room (same room):
a) double pole 30 amp for the drier
b) 20 amp dedicated recepticle for washer/drier
c) 20 amp (other recepticles)
d) 20 amp heater
e) 15 amp lighting

 

[Toller]

There are 5 circuits in the bathroom / laundry room (same room):
a) double pole 30 amp for the drier
b) 20 amp dedicated recepticle for washer/drier
c) 20 amp (other recepticles)
d) 20 amp heater
e) 15 amp lighting

And "C" is GFCI, right?

 

[deans]

C) is a GFCI receptacle on a NON GFCI breaker. Other receptacles on same circuit are on the feed-through.

 

[Toller]

C) is a GFCI receptacle on a NON GFCI breaker. Other receptacles on same circuit are on the feed-through.

Thats all you need.

 

[RBM]

Putting a 12awg on a 15amp breaker is not the problem. Reducing the wire size downstream is!!

 

[deans]

Dear RMB,

I am reducing the wire size downstream from 12 to 14 AWG on the 15 amp breaker for the portion of the circuit without a shared neutral (see full description previously posted). Based on what others say there is no code issue here. Your argument that later no one will know not to put a 20 amp breaker in in the future is false. They will know because there is currently a 15 amp breaker installed so they need to find out why before switching to a 20 amp breaker. You just can't go replacing 15 amp breakers with 20 amp breakers or 20 amp with 30 amp based on the wire size entering the main panel. Unless you can provide some other argument for your statement other than the debunked argument above I am going to proceed as planned.

Thanks,
William