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50A Receptacle for Welder - What size box?

yellow_boss

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Apr 20, 2013
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First off, 6/3 is difficult to work with!

I'm installing a 50A in-wall receptacle (NEMA 6-50R) for my welder, a Lincoln Power Mig 256. I have the correct 50A double pole breaker for my panel and it's about a 15ft run from main panel inside the house to the benchtop area in the attached garage where I'd like the box installed. I have 6/3 NMD90 ROMEX copper stranded wire for in-wall run and the sheetrock is already cut and holes all drilled for the cable run. There are 3-conductor wires (red,black, white) and a bare ground wire. I know only need to use two + ground (red, black and bare) for the welder but I want to install 6/3 in case I re-purpose the box later into an electric vehicle charging receptacle.

The NEMA 6-50R receptacle has four mounting screw holes that match up with the mounting screw positions in a standard 2-gang box. So, I picked up a 2-gang box, 2-1/2" deep I think it is, and figured I was good to go. Not so!

Before installing the box in the wall, I figured I'd try to connect and fit wires into receptacle and box then try to tuck it all in while it was sitting on the work bench before diving in to install the job - a dry run I guess you could call it.
After pulling enough wire (6-8 inches, longer for the ground to loop it ion ground screw on box) out of the box to make the connection there is no way those 4 thick, difficult to bend, 6/3 wires are fitting into that 2-gang, no way! So, I gave up, figuring I don't have the correct box for the task.

I'm obviously not an electrician but I have a good understanding of the install process and no fear at all of running the wire and safely making the connections at the receptacle and panel. Can anyone tell me what size box I need to fit that darn 6/3 in there!!?? :question:

:canada:
 
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510ebl

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Jan 20, 2015
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Southern New Jersey
This is the approach I took, and it worked well surface mounted. I expect your main concern is having the correct 4” cover to accept the 6-50 receptacle properly.

YouTube link


At 9:04 is a good look at an application like I believe you are trying to accomplish with a blue plastic quad box and I believe a Leviton 4934 cover (check that number before buying)
Different plug, same idea...

YouTube link

.
 
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yellow_boss

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That's exactly what I need. At 2:46 the part # of the box is provided too. Thanks for the reply!
 

Bert_

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Why 6-3? No welder needs the neutral. Not sure about Canada but here that welder can run on 8-2nm. It's about the biggest welder you would plan for in a home shop.

I often use a 4" square 2 1/8 deep metal box with mud ring for this type of receptacle. These plugs take a little force to insert and remove. You don't want a box that will flop around in the wall.
 
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yellow_boss

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I want to install 6/3 in case I re-purpose the box later into an 50A electric vehicle charging receptacle
 
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yellow_boss

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I already bought material, 6/3, for the job.

I grabbed a 4-11/16 box yesterday, with the adapter plates for the NEMA 6-50R receptacle. The extra volume in the box with that gauge wire worked much better than trying to stuff it in a standard 2-gang box, that's for sure! It even left me enough room to leave the unused white neutral in there without snipping it off, in case I need it for a box re-role to an electric car charging receptacle. I'm considering building a detached garage this year so if I do the welder will get moved to the new digs and I'll re-purpose this box when required.....there's probably an electric car in my future at some point. A 4" square box would've worked too, but I figured why not go with the extra volume. It's all installed, just need to connect it to the panel today.

I appreciate the replies, thank-you!

Steve
 

frankjdm

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Sep 16, 2012
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I already bought material, 6/3, for the job.

I grabbed a 4-11/16 box yesterday, with the adapter plates for the NEMA 6-50R receptacle. The extra volume in the box with that gauge wire worked much better than trying to stuff it in a standard 2-gang box, that's for sure! It even left me enough room to leave the unused white neutral in there without snipping it off, in case I need it for a box re-role to an electric car charging receptacle. I'm considering building a detached garage this year so if I do the welder will get moved to the new digs and I'll re-purpose this box when required.....there's probably an electric car in my future at some point. A 4" square box would've worked too, but I figured why not go with the extra volume. It's all installed, just need to connect it to the panel today.

I appreciate the replies, thank-you!

Steve
What adaptor plate you have for the 4 11/16 box? I try to find this Thanks
 

nadogail

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I don't think I have ever seen an outlet box that was too big.

I have seen a lot of them where you had to use your hammer handle to push the stuffings in enough to make everything "fit".
 
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