Multiple outlets on 240V circuits?

[Josiah Bartlett]

I have a single 30A 240V circuit run in my shop right now, and I share it by either plugging in my Unisaw or my air compressor. Both have 10 gauge wire going into the tool and were wired that way when I got them. The wire from the panel to the socket is 8/3. The Unisaw is a 2HP unit and the compressor is a 5hp.

I never run them simultaneously, but it would be nice to leave them both plugged in all the time. Is there a problem with multiple 30 amp receptacles on a 30A 240 branch circuit?

This is in a building that was built in 1975, so its all old work.

[Montgomery Scott]

Not a problem. I have a similar situation where I wired a 20A socket and a 30A socket in series to be able to plug my MM16 in one and the TS or jointer in the other.

[Dick Sylvan]

I recently had my shop rewired by an electrician and have two 240v, 30A circuits. One of them has 3 outlets which I will use for TS and bandsaw, but they will never be running at the same time. The third outlet is for tool placement flexibility.

[Jim Becker]

Yes, you can do it. I find it best for the circuit to be split in a j-box, rather than trying to chain at the outlet...space is pretty limited inside most outlet boxes and 10 gage is bear enough to bend as it is.

That said...be careful with the combination you propose. A compressor really should be on its own circuit because it has the ability to passively run at the same time as other machines. Same goes for a dust collector. I'd not hesitate to share a circuit between a table saw and a band saw, however, or a lathe and the table saw. It's unlikely that you'd ever run them both at the same time. ;) Unless you have really long arms! (or tend to leave your machines "on" when you shouldn't)

[Lewis Cobb]

I'm late to the party here but I asked this exact question of a licensed electrician on the "allexperts.com" website and was told it's not a problem so your good to go.....

[glenn bradley]

I'm with Jim on the J-box. Daisy chaining this type of outlet would require 2 wires under the screws which I am told is no-no. One other caution is to have a good visible switch on the compressor so you know it is manually OFF and won't suddenly kick on while you're sawing.

[Jeff Sudmeier]

I'm with Jim on the J-box. Daisy chaining this type of outlet would require 2 wires under the screws which I am told is no-no. One other caution is to have a good visible switch on the compressor so you know it is manually OFF and won't suddenly kick on while you're sawing.

Nah, it wouldn't require 2 wires under the screws but it would require you to twist the 2 wires with a short jumper then put a wire nut on it. Not fun with 10ga wire, but it can be done. Whatever you prefer to do...

[Pete Brown]

My local inspectors won't allow two outlets on a 240v circuit. 240v tools are considered to be stationary and need a dedicated outlet for each one.

I recall looking that up in the code a few years back, and thinking it was a reasonable interpretation.

To Montgomery:

Having two different rated outlets on the same circuit strikes me as definitely wrong and a little dangerous. When the MM16 is drawing 30 amps (depending on how everything is wired), you end up with 30 amps crossing through an outlet only rated for 20. The better option would be to use two 30 amp outlets and change the plug on your TS to be 30 amps. The best solution would be to have two separate circuits, each with appropriate outlets.

Pete

[David G Baker]

I agree with Jim on putting a dedicated circuit on equipment that has high starting current draw and also agree on the use of J boxes. I hate stuffing wires into small receptacle boxes and on several occasions have found that a wire worked loose while trying to manipulate the receptacle back into the box. I do use more pigtails than I once did but I use the larger/deeper boxes when I do.

[Tom Veatch]

My local inspectors won't allow two outlets on a 240v circuit. 240v tools are considered to be stationary and need a dedicated outlet for each one.
...

Code interpretations seem to be quite variable with the local jurisdictions. The receptacles in my shop are all dual voltage like this one (http://www.leviton.com/OA_HTML/ibeCCtpItmDspRte.jsp?a=b&item=8120) and wired with 3-wire 240v circuits. So I've definitely got multiple outlets on my 240v circuits and there was nary a squawk out of the inspectors.

[Pete Brown]

Code interpretations seem to be quite variable with the local jurisdictions. The receptacles in my shop are all dual voltage like this one (http://www.leviton.com/OA_HTML/ibeCCtpItmDspRte.jsp?a=b&item=8120) and wired with 3-wire 240v circuits. So I've definitely got multiple outlets on my 240v circuits and there was nary a squawk out of the inspectors.

Definitely. That's why one should always check with local inspectors before doing anything even remotely questionable :)

Pete

[Rick Christopherson]

Definitely. That's why one should always check with local inspectors before doing anything even remotely questionable :)

PeteActually, I think the wrong question was asked of the inspector, and therefore the wrong answer was given by the inspector. I would be surprised if the local code prohibited multi-outlet circuits. The inspector is accustomed to homeowners asking about home appliances, such as ovens and dryers, so he would have responded accordingly. My guess is if the original person stating this had pressed the issue further, the inspector would have changed his answer.