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

[William.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

[Bob Vaughan]

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).

1. 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 unspecified.

2. 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.

1. 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.

2. options 3 and 4 combined.

[Bob Vaughan]

I should have said:

1. options 3 and 4 combined, without the shared neutral.

[RBM]

[toller]

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.

[DL]

You could also mark the breaker and note in the breaker box that the circuit is wired in part with 14/2 so no breaker larger than 15amps should be used. Won't prevent someone from adding a larger breaker that's determined, but it should stop most people. Hopefully the load required from the outlet(s) at the end of the 14/2 branch will be less than 15 amps in total. You can't always save people from themselves. It is entirely possible for someone to put a larger than 20 amp breaker on the circuits wired with 12/2-3.

David

[RBM]

[gfretwell]

I use a code book every day and I do have one handy. I will be anxiously awaiting the reason "reducing wire size downstream" is illegal.

[Doug Miller]

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]

Trace the cable. I'd certainly be inclined to do a bit of checking, if I saw a

12ga wire coming off a 15A breaker.

[William.Deans]

Greetings,

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, William

URLS:

or

[Philip Lewis]

or, you could be nice, and provide a written explanation stored someplace close to the box. (at least tell them where to look --- "see junction box above north wall in room blah")

[Doug Miller]

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

[William.Deans]

Greetings,

I have added a box size calculation spreadsheet at bottom.

Hope this helps, William

[William.Deans]

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.

[zxcvbob]

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 it's buried.

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.

Best regards, Bob

[John Smith]

Every 15 amp breaker in my house (Built in 1986) has a 12 gauge feeder to the first recepticle/box.