subpanel circuit wiring in detached pole barn

[bird73]

I have a detached pole barn that I am installing a subpanel into. Running 100Amp feed to the barn through 2-2-2-4 Aluminum wire. The inside of the barn will be finished eventually with 3/4" plywood 4ft from the floor and steel above that. I want to recess the subpanel in the wall and create an open cavity that is 10inch wider than the subpanel all the way around. The garage will be wired with NM wire which will reside behind the walls.

My question is will the NM cable being exposed for 10inches between the metal sub panel and the divider for the wall be a code violation? The wire will be stapled to the plywood the panel is mounted to and will run into the wall through holes in the plywood. Does all of the NM cable need to be buried in the wall or will this mall amount around the panel still meet inspection?

 

[mike93lx]

First off, you need to share location when asking about anything code related. Countries, states and localities can vary.

You can't run a 100a breaker to feed that line. 90a is the max for a sub with #2al. This is the breaker in the house at your main panel. Also, what type of wire did you run (ser, MHF, URD, Xhhw) and is it above ground or below?

If your sub has a 100a main in it, that is fine to leave as it is just a disconnect.

In a surface mount panel, some wire will always be exposed. If it is somewhere that damage will be expected, a cover out of plywood would be prudent, otherwise I would leave it.

 

[acer66]

To add to #2 I would make something like a picture frame for the panel that covers the 10” around it which can easily removed to access the area if needed and sits flush with the finished wall unless you like the look of the wiring.

 

[Terry D]

Are you doing this so you can add future circuits. With the panel flush mounted and when the walls get covered, how would you run the wires behind the walls anyway without removing the plywood. I don't see the advantage of having 10 inches around the panel open. I would stub some empty conduits up into the ceiling and maybe some flexible conduit to a few surface mounted J-Boxes. Then you could add to these later for future circuits

 

[bird73]

Thank you for the feedback. The barn is in New York state in Oswego County.

My reasoning for mounting the panel flush mount with a border area around it is the panel will be located where corrugated steel will be placed for the walls. I would need to make a wooden perimeter around the panel to mount the J-channel for the corrugated steel. It is was easier to set that back 10" from the box. But if it is going to cause an issue with inspection, I can still make a change or make a removable cover in the wall if that is needed by code to cover the wires.

I appreciate the help

 

[dcg9381]

This one may be a tough one. 3/4 ply may be unacceptable for "residential code" as an interior panel. NM wire (romex) is typically used in residential type structures.

I think your "will it pass code" question is a pretty good one. What inspections do you have?

I *may* have some NM wire in steel building that is sheeted in 4x8' OSB as interior walls. I chose this setup because I can just pull a 4x8' panel and get behind the wall to re-work something. If we consider this building a "residential structure" the "residential" wiring will pass, but the OSB would likely fail due to fire retardant requirements in IRC (flame-spread/smoke-developed index).