Can I turn a 12x12x4 pull box into a large junction box and a couple of other questions re: conduit and wiring for my woodshop

[JEG in Raleigh]

I have a free-standing 3-car garage with an apartment over it and it has its own meter and 200 amp service. I still have room in the panel for 6 dual-pole breakers. The garage is fully insulated and drywalled. I am turning this garage into my home woodshop. I don't need any new circuits other than machine circuits. I'll have three 3 hp, 240-volt single-phase machines and one 5 hp 240-volt 3-phase machine, and one 3 hp 240-volt 3-phase machine. I'll be buying a 10-hp rotary phase converter to run the 3-phase machines. All 5 machines are or will be on mobile bases so they will be moved around to create room when necessary. OK, that's the background.

I'm going to need to run EMT for the circuits for these 5 machines. My panel is recessed/flush with the drywall and my conduit is going to run on top of the drywall, so the conduit cannot enter the panel as things now exist. The only knockouts that I still have available are in the bottom of the panel......the top has a couple but it's very crowded. Since I am going to have 5 runs of EMT......one for each machine, I need a code-compliant way to get those conductors to the panel. I would like to use a large pull-box as a big junction box...maybe like this one.....https://www.cooper-electric.com/product/detail/80645/hoffman-ase12x12x4......into which my 5 runs of EMT will terminate. My intention then would be to run the proper gauge of Romex for each of the 5 circuits, out of the bottom of the panel..... across the stud bay.....through the adjacent stud.....into the adjacent stud bay, and then into the back of this big junction box, secured with cable clamps. I would transition from Romex to THHN in the big J-box. But there are no knockouts in the back of this 12x12x4 junction box, and I would need 5 of them.

QUESTION #1 - By code, can I use this box as a J-box, and if I can, can I punch 5 knockouts in the back and also be in code compliance? If so, is there a minimum spacing required between the knockouts?

QUESTION #2 - My intent is to have twist-lock receptacles on the ceiling for each machine, with flexible cords with male twist-lock ends running from the machines to the ceiling-mounted receptacles so I would have some flexibility to reposition the machines. Would this setup meet the code for strain relief?

QUESTION #3 - I am one person and will only ever use one machine at a time. Can I have several receptacles on a single 240-volt circuit? I'm thinking of a 40-amp circuit with the three 3 hp single phase machines on it. Would the magnetic starters of each machine all I would need for overload protection. I would want to do this to the code, so if this is not legal, please let me know.

Thanks!

 

[tom baker]

With no occupation listed and a very long post, this appears to be a DIY post, which we do not allow per forum rules. We would advise for your safety and fire insurance to hire an electrician, get the required permits

 

[Dennis Alwon]

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