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Coytee

Dedicated circuit question

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Been tinkering in the basement getting some wires run across the room for future use. I might also put some amps across the room and will be running a dedicated circuit for them.

I happen to have 3 unopened (and therefore returnable) 250' rolls of 12/2 w/ground wire. I also happen to have maybe 50' of 10/3 wire, w/ground. I might be able to get by with 50'. If not, I'd speculate certainly less than 100' which means I might need to buy another length.

1. I like the idea of using the 10g wire since I've already experienced outlet overload upstairs with 9,762,389 things plugged into a single outlet and having the breaker trip when the wife turns on the Hoover.

2. I understand if I had independent runs of 12g wire and split my load up I would probably not have the above problem.

3. then I get confused because I think I"ve read that #2 would (could) possibly cause some ground loops so I'm better off if I keep all on a single breaker (which is fine by me)

Thrust of my question is.... I have three strands of 10g wire yet, believe I only "need" two (not counting the ground). So.... can I create any benefit of having this extra wire in there? Will it simply be taking up space and sitting dormant?

Any thoughts on a use for the third 10g strand?

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You can use the third wire to create a second circut that shares the neutral with the first circuit. Just make sure the two circuits are on different legs at the panel.

You will have a lower voltage drop with the 10AWG wire than with the 12AWG wire.

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You can use the third wire to create a second circut that shares the neutral with the first circuit. Just make sure the two circuits are on different legs at the panel.

1. I'm not an electrician

2. My brother in law is (however I hate to impose family things on him and know he appreciates that)

3. Because of #2, I'm doing the gruntwork of pulling & setting up and will even wire the outlets....letting him come in behind me, check it all and hook a couple wires to my panel box.

I only say that so you don't feel like you are advising me and I'm going to go electrocute myself.

So, with that said... I might presume that in english what you just said above is essenatially to split the outlet into two halves so each half will be on its own dedicated breaker?

Use the (what I think is) red wire along with the black as my hots and use the white as the common neutral?

Interesting.

If above is accurate, and if using 10g is over kill....would having TWO 10g wires to a single outlet be extra over kill or is that about the only functional use I can get out of this extra wife?

Unmentioned is a reality that my distribution panel is near (if not) full of breakers already and I might have to get a second panel box for the basement (run off my main box of course but move a couple circuits)

If I understand your idea then as good as it may be, it might chew up more circuits than I can spare.

If I do not understand your idea then maybe you will clarify

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If you follow Malcolm's advice, you will be
violating electrical code in most jurisdictions.

There is a viable
variant to his suggestion: 3-conductor with ground can be used for a
220-volt connection to a secondary box, where the two hot phases of
220V AC can be separated into two phases of 110V. You add a 220V breaker to your existing panel (using two adjacent 110V slots), run your 10 gauge 3-wire from that breaker into the new box you already mentioned as a possibility, then add 110V breakers to that box for your new circuits. If you locate the new box near where you intend to add your new outlets, you can minimize the length of 12 gauge wire between the new box and the new outlets.

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Care to quote code?

What I suggested is perfectly legal according to the NEC, some version of which is the base document for most local electrical codes. It is legal where I live. No need to run a 220V circuit to another box. It is called a multiwire branch circuit.

OP:

Yes, you can use red for one hot, black for the other hot, and white for the neutral. You can use a two-pole breaker, or two single-pole breakers. It you use the latter, the handles have to be tied together. You can use a split receptacle or two separate receptacles.

FWIW 10AWG is not overkill. Minimum gauge for a 14AWG for 15A circuit, 12AWG for 20A circuit. Sometimes due to ampacity issues, code requires use of larger wire. Even when it doesn't, using larger wire reduces voltage drop which is a good thing.

I guess I should also tell you about the downside of a multiwire branch circuit. If somehow you lose the neutral connection to the utility's transformer, you can wind up with anything up to 220V across your equipment depending on how the load is split between the two circuits. It doesn't happen often, but when it does, the results can be spectacular.

FWIW if I want more than one circuit, I run separate cables (hot, neutral and ground) of appropriate gauge for each circuit.

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If you use a common breaker (220V) or physically tie two `110V breakers together, then you are covered under most areas' codes for multiwire branch circuits. Without this caution, however, you're treading dangerous territory.

I agree completely about wire gauge; use the heaviest you can budget, regardless of your nominal current requirements. I have yet to regret having too much power available on a circuit...

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How many circuits do you need for your application and what amperage breakers will you be going with ?

Rather going with one high amperage branched circuit you may be better off using multiple 12 Guage wire runs and 20 amp breakers.

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Here's what I'd do:

Measure and go buy enough 10/2 w/gnd to run to the outlet of choice and buy a 30A 120V breaker for your box. I have been told by an audio installer I trust that it is legal in Tennessee to install a double box with 2 sockets on a dedicated 30A circuit. That is what I almost did recently and may still when I get my second sub amp running.

Here's why:

AC runs both ways. If you use the red as + and the black as + with the white as neutral and the ground as the safety ground, you could supply 30A down each + and have only the one white neutral trying to "return" 60A. It may be legal, but I wouldn't risk overloading the neutral. In a 240V circuit, the red and black "alternate" between + and "return" with the white acting as ground and often there is no other safety ground used. Newer codes spec the bare ground wire as a chassis ground. (120V 3-way lighting circuits are a whole 'nother can of worms.) I would not use the 10/3 you have with an unused wire, though that is possible. The unused wire will cause too much confusion 10 years from now when you try to figure out what you did.

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I would not use the 10/3 you have with an unused wire, though that is possible. The unused wire will cause too much confusion 10 years from now when you try to figure out what you did.

Interesting point. Let me alter the picture just a bit. What if the third wire (red?) was cut flush with the casing. In other words, although it might be a 10/3 wire, only 2 "pigtails" come out several inches. The third pigtail (red) is cut short.

I've got probalby enough of this to run a single line all the way around my room... hate to just toss it and buy more if I could use it.

As for buying more, I have no idea how much conduit costs...but if a dormant third wire is indeed a possible point of confusion to someone in the future (certainly a reasonable point) what if I simply yanked the wires OUT of the casing and strung the single wires through conduit, leaving the third wire out all together?

Admission: I'm not really thinking about doing the conduit thing so it's more a question of curiosity. The hassel to run the conduit verses simply buying mroe wire... just isn't worth it in my book. I do however, hate the idea of just tossing this wire away because it has a dormant 3rd wire.

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#1- 10/3 is totally unnecessary and somewhat more difficult to work with. Remember, you will be terminating this wire to a 15A receptacle, #14 or #12 is just fine.

#2- If you do run the 10-3, don't cut the un-used wire off. Just cap (wirenut or tape) it off. If you choose to use it in the future it will be there.

#3- You most certainly can NOT "tie" two single pole breakers together, leagally. It has to be a 2 pole breaker.

#4- Wire is cheap. Go buy the proper wire for the job and do it right.

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