Since you're so confident that it's a violation, perhaps you'd be good enough
to cite the article of the Code which prohibits it?
Remember, he has *twelve* gauge wire coming off of a *fifteen* amp breaker
(for which 14ga would be sufficient), and he's reducing it later to 14ga.
That's *not* a problem.
Doug Miller (alphageek at milmac dot com)
Although I cannot quite explain it, I know that everyone loves photos.
I have included them at the URL below.
Thank you all very much again,
Lotsa wires in that box... Have you done a capacity calculation?
Mininum size of the box is
2.25 cubic inches per 12ga conductor, plus
2.25 cubic inches for the equipment grounds, plus
2.00 cubic inches per 14ga conductor
If some idiot does replace the 15A breaker with a 20, it's not all that
dangerous in this case. IIRC, the ampacity of #14 UF cable is 20A even
though the code limits you to 15A. The #14 cable is underground, so if
it does get overloaded it has a nice heat sink to protect it for a
while, and if it ultimately burns up it will not start a fire because
Tape a little card inside the panel cover that says "Breaker #5 is 15A
because the circuit contains a mix of 12 and 14 ga wire", or write
something to that effect with a Sharpie.
And your code reference is.............?!
It is not only acceptable, but is done all the time. Anyone who would
increase a breaker size without checking the circuit out should not be doing
any electrical work.
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
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
I am not using AFCI or GFCI circuit breakers in either case.
PS: The cost savings come from using wire which is already run instead
of having to run new wire in difficult places.
[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
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.
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
His other posting also indicated that the 14/2 was buried UF, already in
place, and a PITA to change out.
As I see it, he has several options.
1. use the existing wiring as is, with existing breakers, and no handle ties
(legal under current NEC??, but not legal under CEC).
2. replace the single 20A breaker with a dual 20A breaker to match the
dual 15A in the next slot, and tie the adjacent 15 and 20 together.
(this will leave the extra 20 unused for future use)
unsure about availability of handle ties, as breaker type is
3. run a piece of 12/2 (or 14/2) from the panel to the utility box, and
move the 15A circuit off the 12/3, thus avoiding the shared neutral.
You may want to move the entire circuit into a new utility box.
4. replace the buried 14/2 UF with 12/2 UF, and the breaker with a 20A,
using the existing 12/3 w/shared neutral configuration.
5. options 3 and 4 combined.
-- Welcome My Son, Welcome To The Machine --
Bob Vaughan | techie @ tantivy.net |
Thank you very much for your input Bob. I went with option One (see
other posts) because it was easy and code compliant.
Also, I actually like the shared neutral when possible. Less holes to
drill / wires to run / voltage drop / fewer or smaller boxes to install
/ neutral bar holes used* / grounds to come lose / etc etc. These are
general benefits, not specific benefits of this job.
*Believe it or not I had one subpanel with all mini-breakers that ran
out of neutrals bar holes but still had slots for breakers. Inspectors
here will only allow one neutral under a terminal on the neutral bar
but grounds can be twisted.
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