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Eric Gustafson
02-21-2008, 1:24 PM
When I wired my DC, I used the 30a plug with the horizontal prongs. I have also seen the twist lock plugs, and might use those later for the rest of the tools.

The plug I used must be installed, one each, in a double box. The configuration of the twist locks I saw at HD, seem to fit either a single box, one each, or a double box two each. Is that correct?

Rob Russell
02-21-2008, 2:33 PM
Eric,

It'd help if you posted the NEMA configuration of the receptacles you're talking about. The NEMA configuration should be molded right into the face place of the receptacle.

For example, I'm going to guess that the plug you used for your DC is a 6-30.

If you're talking about the twistlock version, that would be a L6-30. The locking version does have a smaller diameter opening in the cover plates. The locking version is basically about 1.7" where the larger straight blade version is a 2.25" diameter opening. There are plates available in single-gang size with that larger opening.

Rob

Chris Padilla
02-21-2008, 2:53 PM
Right...I don't recall seeing double-ganged coverplates of either the 6-30 or L6-30....

Eric Gustafson
02-21-2008, 3:33 PM
The plug I used for the DC was definately 6-30. I will however, look at the hardware on the way home today and get back to you what locking plug I was looking at. As I looked at the related hardware for the locking plugs, I did see covers that looked like it would fit two plugs.

I might be wrong, though. Let's see I was wrong once. :rolleyes: Was it in the 90's or the 80's? ;)

Steven Wilson
02-21-2008, 3:40 PM
Eric, you'll need to do a box fill calculation to see if your box and cover can support two recepticals. With my twist locks (20A or 30A) you really only have enough room for one set of wires in the box.

Jim Becker
02-21-2008, 3:49 PM
While my DC uses the simpler "prong" type 240v plug, all of my 240v outlets in the shop are either 20a or 30a twist locks, depending on the circuit. Rob already described the alpha-numeric designations.

As to more than one in a box...somewhat tough to do. Even if the code might allow it, having more working room is a nice thing. For those that I installed in a double box with a single mud-ring, I was much happier with the working conditions. Cramming these large outlets in a single box, especially with #10 wire on the 30 amp circuits was "not fun".

Chris Padilla
02-21-2008, 3:59 PM
The larger 4 11/16" boxes *might* have enough room for such things but I don't know for sure.

Rob Russell
02-21-2008, 4:25 PM
Cramming these large outlets in a single box, especially with #10 wire on the 30 amp circuits was "not fun".

Yeah, especially when you have 10/3 running into a box and running out to supply another box. #10 is stiff enough so, even using the big 4 11/16" boxes, it can be "fun" to properly get all the conductors tucked back inside.

Professional electricians would probably sneer at us for comments like that, given that they have to work with conductors that go up to more than an inch in diameter. Imagine that stuff - OY!

Chris Padilla
02-21-2008, 5:26 PM
We call in our Governor to handle those situations, Rob! ;)