Next wiring question

[Dave Norris]

Hi,
I'm still working on the wiring for the new shop. The panel box is a 100 amp service off the house service. The neutral and the ground are split. I'm wiring a 240 circuit with 10/2 romex. The two insulated wires are hot, and the ground is bare. I'm 95% sure of this, but I wanted to check... the bare ground goes to the ground side of the box, as there is no neutral in a 240 circuit.

Is that correct?

Thanks!

[Brad Sperr]

That's correct. If this is a subpanel, just make sure that your neutral and ground busses are isolated from each other.

[Cliff Holmes]

Yes, each insulated wire goes into a separate side of a double breaker on the panel end, bare wire to the ground bus

[Prashun Patel]

What are the present and future demands on yr 240v circuits? I was counselled by my electrician (I'm not saying it's Gospel, just something to consider) that if a single tool is going to pull more than 20A, then one should run 10Ga on a 30A 240v breaker. However, if you're trying to support multiple tools each of which pulls < 20A @ 240, then it's preferable to run multiple 240v circuits on 12Ga terminating in separate 20A breakers.

His argument is that a) it's best to size the breaker as close to the limit of the tool to prevent it from burning out in a shorted sitution, and b) it's a little easier to work with 12ga than 10ga wire...

FWIW, Prashun

[Steve Schoene]

Yes, working with 12 is easier, but changing wire is tough, so if there is any chance you would want 240 v power that would be more than 20amp, wire with 10 gauge, but fuse with 20 amp fuses. That way you just have to change the breaker (and outlet) to go to a 30 amp circuit.

[Aaron Wingert]

You've got it Dave. Most of the time there isn't going to be a neutral. Since one of your wires is white, which is indicative of a neutral, you'll need to color-indicate that wire as a phase conductor...Red. A few wraps of red tape in the panel near where it hits the breaker will do. And yes, land that ground on the ground bar.

[Chris Padilla]

Your dryer outlet is a good example where you'll often find a neutral in a 240 V circuit...it is used to power the 120 V light bulb (and perhaps other things).

[Dan Hintz]

Usually wrapping the white line in a few wraps of black electrical tape indicates it's live...

[Bernie May]

when running 240V in your shop, run 10G wire instead of 12G and put breakers sized to your equipment. some time from now when you buy that 5HP "whatever", you will be glad you did. Swap out the 20A breaker with a 30A and you are good to go. It is a bit stiffer but not not that bad. when you want to daisy chain several outlets, just use a double box to give you extra room and put a single outlet on the front.
-bernie

[Tom Hammond]

when you want to daisy chain several outlets, just use a double box to give you extra room and put a single outlet on the front. -bernie
Especially when using 10 wire. fyi - in Ohio, code requires that you wire-nut your line and load in the box with parallel tails leading to the recepticle. The reasoning is so that if the recepticle fails, it won't kill the ones down the line. For the most part, it's a huuuuuuge, annoying waste of time.

[Jason Roehl]

Tom, there is another reason for pig-tailing receptacles and switches. It is much, much easier to properly tuck the wires into the box, and only have a couple hanging out to hook to the switch or recep. Having 5 wires screwed to a recep, and then trying to cram all of them back into the box is a recipe for a loose connection. Personally, any time I do any wiring, I also try to keep the open end of wire nuts down so they don't fill with dust and dead bugs. (I hate taping them, but that is required by code in some places).

[Chris Padilla]

Also, one more reason, Tom and Jason: safety. The current doesn't have to flow through the outlet if it is pig-tailed.

[Dave Norris]

That helps, thanks!

Overall, I know the 12awg vs. 10awg can cause some debates. I suppose if I was doing 2 or 3,000 feet of wiring, it would matter more to me. I'll be able to do all my circuits with under 100', so I'm a 10awg supporter. The 10 minutes of extra hassle installing the heavier wire is far surpassed by the 2 hours of changing out a failed motor. Also, I have a couple 5hp motors already, so the higher gauge does give more options. Plus, I read somewhere a while ago that the #1 cause of premature motor failure is insufficient current, and I know there is more to that than wire gauge, but I just usually go with 10 for the machine circuits. I also pigtail my connections.

Thanks again.