MC Wire for Metal Garage

[gguertin]

I wired up my metal garage like many I saw on here using MC and had the inspector out here today and he is telling me I still have to space 1 1/4 away from the wall.

Being a metal garage I really don't like the idea of drilling holes through the studs worried it will weaken the stud.

What options do I have now?

 

[mike93lx]

Conduit.

MC needs to be treated the same as NM. Protected from damage

 

[ycgoat]

I think You can put boxes up high and run the MC down the side of the posts.

 

[Norcal]

As said by mike93ix in post #2 MC is no different then NM sheathed cable "Romex®" that it needs to be protected from physical damage, use EMT instead.

 

[gguertin]

So much wasted money in wiring .

Should have just used romex.

 

[brownbagg]

pvc conduit

 

[mike93lx]

So much wasted money in wiring .

Should have just used romex.

You'd be in the same boat

You can just sleeve the existing MC with conduit in the places subject to damage. No need to rip it all out

 

[gguertin]

I dont have links at the moment but ive seen pics here and then videos all over youtube... I ran the cable behind the stud between the stud and siding in the gaps. The complaint he has is that there at the stud is the problem.

NEC 300.4, Nail plates (1/16" thick steel plate) shall be used where holes for wiring are drilled
or cables are run closer than 1 1/4 inch to the front of a framing member.

 

[mike93lx]

So install nail plates?

Did he claim that wouldn’t be sufficient?

For stuff like this, pictures help a ton

 

[gguertin]

I can’t fit a nail plate behind the wire against the siding at the stud.

 

[mike93lx]

Sharing that picture early would have helped a lot. I don't see an option other than pulling it all out and either re-running it or switching to conduit.

If the wire inside the MC sheathe is labeled thhn or xhhw, you can reuse it in conduit, but I don't know how likely that us

 

[gguertin]

My plan now… pull and rerun same wire on face.
2x4 sideways up stew stud then gaps where wires cross and nailers. Inspector says that will pass. I was going to install plywood walls this way I just lose 3 inches in width I guess. I can use regular insulation though instead of spray foam this way.

 

[Leaflessshadetree]

I've never seen that type of stud, what does the manufacturer recommend?
I'd drill wood or common metal studs some metal studs had knock outs or premade holes.

 

[CraigStu]

Jeez, so it is OK to run the wire in the valleys in the siding but just where it is outside of the studs is the problem? I guess it is more likely someone would run a screw into the stud to support something but still.....BTW, you did some really nice wiring even if it isn't satisfactory to the inspector. Unfortunately you have to do whatever he says. The ability to use standard insulation vs spray foam will help the budget though so it is not all bad.

 

[mike93lx]

Unfortunately you have to do whatever he says.

This isn't really true and we shouldn't treat inspectors as rule makers. They need to provide written support for code enforcement issues

They make mistakes, just like everyone else, and can be malicious, like lots of people are

 

[Zeke]

I think the inspector is being a little too picky. I know the rules, but the siding is up so what is the likelihood of you adding fasteners? You sure you can't make some C shaped plates and slip them between the siding and the MC? I mean if they have to be stamped as protecting plates, buy flat ones and get them bent at each edge so they conform to the channel. Freaking tack them with a welder if you have to.

It would be a shame to redo that. At least run the proposal by the guy. It shows you are trying.

Kinda like this but straight:

 

[Zeke]

This isn't really true and we shouldn't treat inspectors as rule makers. They need to provide written support for code enforcement issues

They make mistakes, just like everyone else, and can be malicious, like lots of people are

It won't be hard for the inspector to cite the code that applies to this. It's his interpretation of that code that counts. Sometimes rules set forth have a primary purpose but affect other factors at the same time. Obviously the 1 -1/4" rule is to prevent running fasteners through cables when you can't see them. In this case that situation has passed.

And it's a necessary but weak rule. A 16d gun nail will sometimes blow through the typical wire protection plate like it wasn't even there and reach well beyond the 1-1/4 depth.

BTW, I can see rerouting a few of the vertical runs to the other side of the stud will get them out from between the studs and siding. You might look for all of those opportunities before tearing up too much.

This reminds me of a story that is totally unrelated. On a new construction job I went into a clothes closet that had the typical builder's shelf and pole arrangement. The closet had a pocket door and the shelf was on the side where the door slid back into the pocket to open. So the carpenter goes in and nails up the shelf ledgers and places the shelf on top, installs the pole and he's off to the next one.

When I went to close the door to paint the backside it was nailed open by the support nails. He had to be using a minimum of 10d nails to pull that off.

 

[sparky 1971]

Yeah, you're pretty much screwed. You can run everything above the ceiling joists and down the side of the joist's and and studs. There might be some MC that can be re used. Shoulda used EMT on the face of the studs.

My plan now… pull and rerun same wire on face.
2x4 sideways up stew stud then gaps where wires cross and nailers. Inspector says that will pass. I was going to install plywood walls this way I just lose 3 inches in width I guess. I can use regular insulation though instead of spray foam this way.

I'm trying to picture that in me head and not doing a very good job of it. What I am seeing looks like ****.

 

[Zeke]

Yeah, you're pretty much screwed. You can run everything above the ceiling joists and down the side of the joist's and and studs. There might be some MC that can be re used. Shoulda used EMT on the face of the studs.

I'm trying to picture that in me head and not doing a very good job of it. What I am seeing looks like ****.

I think he's saying he's going to fur out the walls with flat studs running the wires behind on the surface of the metal studs. He mentioned losing 3". Problem might be that the distance from the face of the new wood stud to the center of the wire is going to be at almost exactly 1-1/4". Is that enough? IOW, the distance from the face of the stud to the MC outer wrapping will be 1".

When wiring a 2 x 4 wall drilling the center of the studs with a 5/8ths bit leaves 1-3/8ths of wood, both sides. Use a 3/4 bit and it's still a tad over 1-1/4".

So I don't get it either. Where is this 3"?

Or, rethinking his statement, he's going to lay flat studs and THEN 1x horizontal furring strips, he calls 'nailers', buying him another 3/4" That should do it. 1-1/2 + 3/4 + 1/2" wall material = 2 3/4" space taken up. Close enough. I think to save money I'd rip 2 x 4's and put essentially 2 x 2's vertically on the existing metal studs, notching for the MC. Gets even closer to 3" overall with ample distance from the face of the furring strips to outer part of the MC.

 

[BillK]

Being a metal garage I really don't like the idea of drilling holes through the studs worried it will weaken the stud.

Are you talking about the metal studs ??? I have seen them in plenty of commercial buildings with holes punched in them for wiring to run through. Most of the metal studs I have seen actually have holes in them for that purpose. I doubt seriously that you will affect the strength.

 

[sparky 1971]

I think he's saying he's going to fur out the walls with flat studs running the wires behind on the surface of the metal studs. He mentioned losing 3". Problem might be that the distance from the face of the new wood stud to the center of the wire is going to be at almost exactly 1-1/4". Is that enough? IOW, the distance from the face of the stud to the MC outer wrapping will be 1".

When wiring a 2 x 4 wall drilling the center of the studs with a 5/8ths bit leaves 1-3/8ths of wood, both sides. Use a 3/4 bit and it's still a tad over 1-1/4".

So I don't get it either. Where is this 3"?

Or, rethinking his statement, he's going to lay flat studs and THEN 1x horizontal furring strips, he calls 'nailers', buying him another 3/4" That should do it. 1-1/2 + 3/4 + 1/2" wall material = 2 3/4" space taken up. Close enough. I think to save money I'd rip 2 x 4's and put essentially 2 x 2's vertically on the existing metal studs, notching for the MC. Gets even closer to 3" overall with ample distance from the face of the furring strips to outer part of the MC.

I think you're right. I missed the part about putting plywood on the walls, but since the switches and plates are already installed, figured that the picture was the finished product.

 

[Norcal]

Are you talking about the metal studs ??? I have seen them in plenty of commercial buildings with holes punched in them for wiring to run through. Most of the metal studs I have seen actually have holes in them for that purpose. I doubt seriously that you will affect the strength.

Those are not steel studs, the OP's building is a prefabricated building, drilling the metal tubing will pepper them with holes, since plywood is the end desire surface mounted EMT should have been used.

 

[ycgoat]

I would re-route the vertical runs to be secured to side of the posts centered between the outside siding and anticipated paneling. The header above the door can be drilled with out consequence. Remove the horizontal run them up 8’+ high and either set boxes up high and come down to outlet’s from the posts, or run the MC in and out of the outlet but all horizontal runs are done above 8’. I also use 10’ metal studs across 2 posts where needed for boxes or straps. But there are several ways to skin that cat.

 

[gguertin]

Spent the weekend redoing everything... Waiting on a gfci breaker for my rv port and then I will have him back out.

 

[gguertin]

clips were added to that stud brace in the picture above. I had to go to the store to get more.

 

[grounded-b]

Now he's going to cite you for not strapping that MC cable. Must be supported within 12" of each box connector and every 6' there after. Running through a bored hole in a framing member is considered a support

 

[gguertin]

They are strapped now I just didnt take newer pictures yet.