i cant figure out how to connect the 6-2 nmb to the thhn ran in flexible metal conduit. i wanted to use a 2 gang box with a wall plate with a 1/2" knock out and make the connection in the box. the wall will be drywalled and want a finished look. i would would also like to be able to convert it to a 50 amp outlet so i can take the compressor with me if i move in a few years. i don't know if i should use a metal or plastic 2 gang box and i cant find a wall plate with a knockout. should i use a blank wall plate and make my own knockout or am i overlooking a more simple solution to give me a finished look and still be able to switch to a 240v 50a receptacle.
wall plate for compressor
- Thread starter dutzk
- Start date
matt_i
Well-known member
I don't think #6-2 and 1/2" knockout are good friends 
I would think 3/4" at minimum.
Personally I would use a 4" square metal junction box with 2 screws at opposite diagonal corners, for now, a flat metal coverplate, you can chassis punch a "blank" plate for a 90 degree fitting that goes to a loop of flex metal or liquidtight. Eventually you will find a dished Raco plate that has the proper round opening for whatever NEMA receptacle you are going to use (the NEMA outlet will be attached to the coverplate only, the coverplate is attached to the j-box).
I have also holesawed flat coverplates for NEMA 14-30 receptacles in desperation (this was with 4-11/16" boxes that I had used) but where I live now my local Home D has a more "industrial" selection of wiring devices & accessories.
I would think 3/4" at minimum.
Personally I would use a 4" square metal junction box with 2 screws at opposite diagonal corners, for now, a flat metal coverplate, you can chassis punch a "blank" plate for a 90 degree fitting that goes to a loop of flex metal or liquidtight. Eventually you will find a dished Raco plate that has the proper round opening for whatever NEMA receptacle you are going to use (the NEMA outlet will be attached to the coverplate only, the coverplate is attached to the j-box).
I have also holesawed flat coverplates for NEMA 14-30 receptacles in desperation (this was with 4-11/16" boxes that I had used) but where I live now my local Home D has a more "industrial" selection of wiring devices & accessories.
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I forgot to mention the 1/2 knockout in the wallplate is for #10 thhn inside the flex metal connected to the compressor. 6-2 nmb from the subpanel. I think I only need 8 nmb but am upsizing so it could be a 50 amp outlet. I was going to do what you suggested Matt, I was just hoping there was a wallplate that would cover the hole in the drywall giving it a more finished look than a flat 4" cover that is the same size of the box. If I can't find one that is the way I will do it. It is just a garage.... Thanks
