Romex to MC Cable and Grounding

[jfalcs]

Looking to add a few circuits to a finished garage for a dust collector, air compressor and table saw. I have a flush mounted panel and the walls are already buttoned up. I'd like to run Romex from the panel to an 8x8 box just above the panel, and then transition to MC cable (was gifted a spool of 10/2 a while back).

Everything I've read so far indicates that this an OK practice, but I haven't been able to determine if its OK to run 3 separate circuits into the same box to make the transitions. Do I need to ditch the large box in favor of 3 separate boxes?

If the single box is OK, is there a cleaner way to handle the ground wires than trying to tie 6 together to the box with a pigtail? Can I install a ground bar inside the junction box and tie to that?

Thanks

 

[sparky 1971]

Yes, you can put everything in the same box, and yes, you can install a ground bar, but I wouldn't bother if it were me. I'm sure you already know that #10 wire is for 30 amps. If you are going to use it for 20 amp circuits, it is ok, but it's going to be a nightmare trying to get the wire on the devices. You'll probably wind up tailing #12 off of the #10, so make sure the device boxes you use have plenty of depth. I wouldn't bother screwing around with the MC, it's going to take more time than you will save $wise and might not save you all that much money by the time you get the proper boxes and MC fittings.

 

[jfalcs]

Thanks Sparky

The #10 is overkill but I already have it and it was free, and opening up the walls to run all Romex isn't gonna work. I have some #12 that might be appropriate for the dust collector so maybe won't need to go #10 for everything. Good call on the receptacle boxes though, I'll make sure I get some good size ones. Appreciate it

 

[alfredeneuman]

MC cable has the exact same "protection from physical damage" rule as Romex.

and opening up the walls to run all Romex isn't gonna work. I

If you need to open the walls for Romex then you'll need to do it for MC

 

[Terry D]

You might want to consider fishing a 3/4 or 1 inch flexible metal conduit from the panel to the J-box. Then you can run all your seperate circuits in that verses individual romexs

 

[sparky 1971]

Thanks Sparky

The #10 is overkill but I already have it and it was free, and opening up the walls to run all Romex isn't gonna work. I have some #12 that might be appropriate for the dust collector so maybe won't need to go #10 for everything. Good call on the receptacle boxes though, I'll make sure I get some good size ones. Appreciate it

Are you planning on running the MC exposed? You can do whatever you want, but that's a no no. It is supposed to be treated the same as romex.

 

[Jim greengo]

Where is dust collector going in relation to panel,is there an attic above the garage*?

 

[jfalcs]

Are you planning on running the MC exposed? You can do whatever you want, but that's a no no. It is supposed to be treated the same as romex.

Well ****, yeah I was. I’d seen it done a bunch so never thought twice about that part. Guess I’ll need to circle back on the whole plan, sounds like I may have to do conduit instead. There is an attic but it’s tight. Just can’t commit to what it would take to open up the walls.

Appreciate the feedback

 

[alfredeneuman]

sounds like I may have to do conduit instead

Use EMT or Sch80 PVC where subject to damage.
All flex conduits are in the subject to the same rules as MC, AC cable, and Romex

 

[dscheidt]

Well ****, yeah I was. I’d seen it done a bunch so never thought twice about that part. Guess I’ll need to circle back on the whole plan, sounds like I may have to do conduit instead. There is an attic but it’s tight. Just can’t commit to what it would take to open up the walls.

Appreciate the feedback

It's done all the time, either in the belief that's it's okay or not caring. I will say from experience that ti's not any more resistant to mechanical damage than romex is. I have broken it with a 2x4.

 

[BillK]

Unless I am reading this wrong it seems like it is perfectly acceptable to use mc cable as long as it is installed right against the wall or ceiling ??

330.15 New Standards for Installing MC Cable | JADE Learning

New for the 2017 NEC cycle is section 330.15, entitled Metal-Clad Cable: Type MC Exposed Work. This new Code section requires an exposed run of MC Cable to closely follow the surface to which it is mounted while enjoying a new permission that allows the MC cable to be installed on the underside...

www.jadelearning.com

 

[alfredeneuman]

Unless I am reading this wrong it seems like it is perfectly acceptable to use mc cable as long as it is installed right against the wall or ceiling ??

Yes, but the same is true for Romex
334.15 Exposed Work. In exposed work, except as provided in 300.11(A), cable shall be installed as specified in 334.15(A) through (C).
(A) To Follow Surface. Cable shall closely follow the surface
of the building finish or of running boards

 

[Shovelhead]

I’ve always done my best not to whack my exposed MC with a 2x4, or a hammer, or a screwdriver. But ya never know about them other folks walking around in yer shed wanting to whack yer ****.