Wiring a 240V outlets

[flatsixcrazy]

I've finally decided to install a 240V outlet next to my sub-panel for an air compressor and a plasma cutter. I'll use Leviton's 50 Amp receptacle and would like to flush mount it into the drywall. I plan to the regular Home Depot's blue outlet box with the tabs, and 8-gauge 3-wire. Would the regular HD blue outlet box work for this purpose? or should I look for something more robust ($$)?

Also, if I want to install two 240V receptacles next to each other (one for the plasma cutter and one for the air compressor) on two separate 50 Amp breakers, can I use the double gang outlet box? or should I install each receptacle into its own outlet box? (Nevermind, I found out the answer is no.)

Thanks in advance for all your help. Andy

[trytryagain]

I think you will have difficulty folding the 4 #8 wires into a box designed for #12 or #14. Best would be to go to an electrical supply store and ask them what to use.

[flatsixcrazy]

Thanks for the tip. I'll give the electrical supply store a try.

[Jazzbass]

I'd have to look, but I'm 90% sure you can't put two 240V outlets in the same box so separate those. You can fit this outlet in a single gang old work box, but it does get a little tight. I've done this but used a deep box vs. the standard depth box. Most pros use a dual gang box. Separate runs, separate wires, separate outlets, separate breakers and you should be fine.

50A for a compressor? That's pretty large. You running a 7hp motor? I have a 5hp IR running on a 30A/10ga circuit and it runs fine.

[ducatithunder]

Use the double gang for each outlet. Youll be much happier in the long run. Alot more room to wire and keeps it less cramped.

50 amp is much for a compressor but atleast youll have room to grow in the long run if you get a larger compressor.

[Rob VN]

Hi Andy,
I'm a volunteer electrician on Habitat houses and I stayed at a Holiday Inn.

For a 50 amp breaker we use 6 gauge wire, typically for the air handler with electric heat.

For a 40 amp breaker we use 8 gauge wire for powering the electric stove.

I agree with the comment you'll want a separate double "old work " gang box for each outlet.

Good luck with your project,

Rob

[flatsixcrazy]

Thanks for the tips. I have the same 5 H.P Ingersoll air compressor as Jazz's, but decided to go with 50 amps in case I need more capacity later on. I took the advice and went with 2-gang old-work box and 6-2 gauge wire. It worked out great.

This maybe too late, but does anyone knows where I can find electrical codes for garage wiring in Loudoun County :-)? I want to make sure it passes the code before I call in an inspector.

Thanks again.

[Rob VN]

Andy,
In FL we have to protect all standard outlets in the garage with GFI socket or GFI breaker. FL follows the National Electric Code. Not sure how your garage is currently wired. The other trick is you are having the new outlets inspected, not the existing wiring. It all depends on the inspector. If there is any doubt go the extra mile to make all your standard outlets in the garage GFI. A happy inspector is a good thing I've learned.

Rob

[smdubovsky]

220V outlets never have to be gfci. Only 115s in a garage (and there are even exceptions for that.)

[AznDrgn]

Any particular reason you need to have it inspected?

[flatsixcrazy]

Any particular reason you need to have it inspected?

No particular reason. I thought it is a requirement to have new electrical inspected?

[trytryagain]

Let the sleeping dog lie.

[N0tt0N]

You only need an inspector if you have a permit :)

[Trak Ratt]

You only need an inspector if you have a permit :)
or your house burns down and the fire marshal decides that your "new" wiring was the culpret.... :p

[AznDrgn]

Thanks for the tips. I have the same 5 H.P Ingersoll air compressor as Jazz's, but decided to go with 50 amps in case I need more capacity later on. I took the advice and went with 2-gang old-work box and 6-2 gauge wire. It worked out great.

This maybe too late, but does anyone knows where I can find electrical codes for garage wiring in Loudoun County :-)? I want to make sure it passes the code before I call in an inspector.

Thanks again.

or your house burns down and the fire marshal decides that your "new" wiring was the culpret.... :p

They have to be able to prove it's new, hard to do that when it's all charred ;).


My previous experience with inspectors is that they rarely know what they are looking at, they don't really open anything to get a good look at what you did, and they are easily distracted by shiny things. Personally I wouldn't bother with pulling a permit and getting an inspection for such a small item unless you just feel like burning $100 and spending half a day to a day waiting for an inspector who will probably have more questions for you about your car than the work they are actually supposed to inspect.