I have placed 1/2" EMT and (13) 4" sq. boxes around the perimeter of my basement, to supply power for light-duty shop eqpt. I was planning to run #12 wire, use a 20A breaker(s), and put two outlets in each box. Questions:
1. Do I need to split this into 2 circuits?
2. If so, should they alternate box to box, i.e. every other box to circuit A, or should I wire one outlet in each box to circuit A, one to circuit B?
3. Can one ground wire serve both circuits?
4. I can't think of a 20A tool I'd plug in, but do I nonetheless have to use 20A outlets? I notice they are a lot more expensive.

Thanks! Robert

 

1. Maybe, depending on exactly what loads you intend to serve by the outlets. If in doubt, use 2 circuits, or a multiwire branch circuit (one with a shared neutral).
2. It's really a matter of preference and judgement. There are advantages to each design.
3. Only if you are using a multiwire branch circuit. Otherwise, you need two ground wires.
4. You can use 15A outlets on a 20A circuit.

One caveat: if you don't know what a multiwire circuit is, then don't even think about trying to implement it. There are numerous rules to ensure safety when using multiwire circuits, and if you don't know what they are, you're literally playing with fire.

 

My understanding is that you only need one ground wire, regardless of whether you run a multiwire circuit or not.

If it were me, I would use a multiwire circuit controlled by two separate 20 amp breakers. I would alternate receptacles, so that each duplex is on a separate half of the multiwire circuit. I would also maintain consistency, such as each right receptacle on one half and each left receptacle on the other half.

If you are n't familiar with multiwire circuits, then just run two separate circuits, two hot wires and two neutrals, one ground.

 

Since this shop requires GFCI outlets, I strongly recommend against the multiwire circuit.

 

Momentary memorl block, I forgot about GFCI protection. Use GFCI receptacles at the first junction box, or GFCI breakers at the panel and run two separate circuits.

 

Not sure why I thought you needed a separate EGC for each circuit. Probably comes from staring at all of the orange IG receptacles at work...

Are we assuming that this is in an unfinished basement? (re: GFCI's)

 

If you are in Canada the you MUST use 20 amp receptacles on a 20 amp circuit.

 

Thank you all for the responses. I think I will do every other box on alternate circuits, as the wiring in each box is simpler. Also, I'll start each run with a GFCI. BTW, I have a bunch of 12/2 NM - can I strip off the sheath and use the B and W wires instead of purchasing THHN?

 

No you can't do that. Besides the NM is solid wire. Too hard to pull though corners. I would use stranded wire.

 

You can never strip the sheating off of a cable and use the wires inside. The inside wires carry no rating and have no markings. Besides, it's really tough to do this and the likelihood of insulation damage is very high.

 

hi
max is 8 outlet per circuit (combination of light and outlet)
or
12 lights per circuit
cheers
pg

 

The NEC imposes no restrictions on the number of outlets (of any sort) on a general purpose circuit for residential applications.

 

Just as a point of reference, the Canadian Residential Electrical Code imposes a maximum of 12 outlets and/or lights on a single circuit. I am not saying this to indicate the Canadian Code is better or anything (really!), but just it does give some guidance in this area.