Surface mounted electric panel - wiring & finishing

[RumbleBee383]

Hey guys

I'm in BC Canada and in the process of wiring my new 32x40 detached garage. I have had an electrician bring 100 amps from my house to a new panel in garage and I am doing the actual wiring in the garage on a separate permit. The electrician surface mounted the panel on a full 4x8 sheet of plywood, stating that because it is mounted on an exterior wall, it can't be flush mounted due to required insulation values of the exterior wall (2x6 studs).

Now that it is time for me to do my part of the wiring, I am a bit stumped as to how to transition the wires from the surface mounted panel and plywood into the walls. The electrician says that I just need to surface mount the Romex on the plywood and run it into the stud bay where the plywood ends. He says the wires can remain exposed.

My question is... how do I finish around the wires where they transition into the wall? I am planning to drywall the walls... do I just cut some slots in the end of the drywall for the wires and install as usual? Can I build a box around the wires that I then cover with plywood or drywall?

Attached is a pic of the panel and what I am thinking of doing.

Thanks for any advice or help!

 

[sparky 1971]

Drill holes in the plywood and go into the closest stud cavity. You could also set a 10X10, 10X12, or a 12X12 junction box, or a 4X4X12, 18, or 24 trough mounted vertically next to the panel with a few ******* between them. Come into the back of the trough and into the panel. That will keep everything hidden and look like it belongs. I personally think the trough would look best. While your at it, you could run a smurf pipe or flex from the box to the attic for the future. Of course, you could always do plan a and build a box around everything after the wire is installed.

 

[BillK]

It would use a bit more wire but if it was mine I would run all of the wires out of the top of the panel into the attic and then back down wherever needed. Then you could build out a shallow enclosure going straight up to hide the wires.

Just curious, do they do the same thing in houses ? Seems strange not to be able to flush mount it, especially in a detached garage. What if the garage was not going to be insulated or heated ? Would the same rule apply ? How do they know ? Just curious more than anything.

 

[sparky 1971]

It would use a bit more wire but if it was mine I would run all of the wires out of the top of the panel into the attic and then back down wherever needed. Then you could build out a shallow enclosure going straight up to hide the wires.

Just curious, do they do the same thing in houses ? Seems strange not to be able to flush mount it, especially in a detached garage. What if the garage was not going to be insulated or heated ? Would the same rule apply ? How do they know ? Just curious more than anything.

I don't think they can come out the top of the panel in Canada. There's a barrier inside to separate the top and bottom halves.

 

[BillK]

I don't think they can come out the top of the panel in Canada. There's a barrier inside to separate the top and bottom halves.

Interesting. Learn something every day

 

[RumbleBee383]

Drill holes in the plywood and go into the closest stud cavity. You could also set a 10X10, 10X12, or a 12X12 junction box, or a 4X4X12, 18, or 24 trough mounted vertically next to the panel with a few ******* between them. Come into the back of the trough and into the panel. That will keep everything hidden and look like it belongs. I personally think the trough would look best. While your at it, you could run a smurf pipe or flex from the box to the attic for the future. Of course, you could always do plan a and build a box around everything after the wire is installed.

Thank you for the suggestions!

This might be a stupid question, but if I were to use a junction box or trough, do the wires just pass through the box/trough or would I need to cut and join the wires inside like I would for a light/outlet/switch?

Also, do I just go out the back of the junction box or trough and directly into the wall?

I've been trying to avoid going under the plywood and through the vapor barrier... with the insulation and vapor barrier already installed, it sure seems like it will be tricky to tape all of the wire entries under the plywood.

That "plan A" picture that I attached... is there anything wrong with doing it like that? I can at least wrap my head around it even if it isn't as nice as what a pro might do.

It would use a bit more wire but if it was mine I would run all of the wires out of the top of the panel into the attic and then back down wherever needed. Then you could build out a shallow enclosure going straight up to hide the wires.

Just curious, do they do the same thing in houses ? Seems strange not to be able to flush mount it, especially in a detached garage. What if the garage was not going to be insulated or heated ? Would the same rule apply ? How do they know ? Just curious more than anything.

Thanks! I had considered going out the top and up to the ceiling. Its a 13 foot ceiling so it seems like it could add some cost for the larger wires for the welder and compressor and others... maybe its really not as much as I think it would be.

I assume that I would need to run plywood up to the ceiling also to give me something to attach the wire to.

I'm not sure if the surface mount rule applies to all external walls or not. My electrician said the building inspector would fail if it was flush mounted due to insufficient insulation. My house's panel is also surface mounted in the basement, but is in a corner and on top of a half wall, so all of the wiring is hidden by extending that section of half wall to the ceiling and it looks flush mounted and has none of the issues that I'm having with my garage!

I don't think they can come out the top of the panel in Canada. There's a barrier inside to separate the top and bottom halves.

This panel is mounted "upside down", so the inaccessible area where the main wire comes in is at the bottom and I can run wires out of the top if I want to.

Thanks for the info, I really appreciate the ideas!

 

[nadogail]

Canada has their own electrical code that is similar to, but doesn’t match the USA code.

 

[sparky 1971]

Thank you for the suggestions!

This might be a stupid question, but if I were to use a junction box or trough, do the wires just pass through the box/trough or would I need to cut and join the wires inside like I would for a light/outlet/switch?

They could pass through, but cut the romex jacket off. I would use a few 1", 1-1/4" or 1-1/2" ******* between the trough and panel, but if the jacket is still on, those ******* will fill up in a hurry. You could put a ground bar(s) in the trough and leave all the grounds in it or run them into the panel. The wiring in the panel will be a lot cleaner if you leave them in the trough. Just make sure you run at least one ground from the panel to the ground bar.

Also, do I just go out the back of the junction box or trough and directly into the wall?

You would have to have something to sleeve the hole. If it were me, I would use a few 2" pvc male adapters into the back of the trough. The hole in the plywood would have to be big enough for the MA to fit, which would make it a lot easier for you to look inside the hole to grab the wires and pull them out.

I've been trying to avoid going under the plywood and through the vapor barrier... with the insulation and vapor barrier already installed, it sure seems like it will be tricky to tape all of the wire entries under the plywood.

Could you get between the vapor barrier and the plywood?

That "plan A" picture that I attached... is there anything wrong with doing it like that? I can at least wrap my head around it even if it isn't as nice as what a pro might do.

I don't know why you couldn't do that, I personally think it would look funny, but it's not my garage.

This panel is mounted "upside down", so the inaccessible area where the main wire comes in is at the bottom and I can run wires out of the top if I want to.

You could put the trough above the panel then. It won't be as far down the wall to have to fish the wires, and I bet you could get them between the vapor barrier and the plywood.

EDIT: You could even put the trough at the top of the plywood and make EMT ******* to tie it to the panel. Then I know you could get in front of the vapor barrier.

Thanks for the info, I really appreciate the ideas!

 

[RumbleBee383]

They could pass through, but cut the romex jacket off. I would use a few 1", 1-1/4" or 1-1/2" ******* between the trough and panel, but if the jacket is still on, those ******* will fill up in a hurry. You could put a ground bar(s) in the trough and leave all the grounds in it or run them into the panel. The wiring in the panel will be a lot cleaner if you leave them in the trough. Just make sure you run at least one ground from the panel to the ground bar.

You would have to have something to sleeve the hole. If it were me, I would use a few 2" pvc male adapters into the back of the trough. The hole in the plywood would have to be big enough for the MA to fit, which would make it a lot easier for you to look inside the hole to grab the wires and pull them out.

Could you get between the vapor barrier and the plywood?

I don't know why you couldn't do that, I personally think it would look funny, but it's not my garage.

You could put the trough above the panel then. It won't be as far down the wall to have to fish the wires, and I bet you could get them between the vapor barrier and the plywood.

EDIT: You could even put the trough at the top of the plywood and make EMT ******* to tie it to the panel. Then I know you could get in front of the vapor barrier.

I am able to get between the plywood and vapor barrier. Its pretty unruly being a 4x8 sheet with the panel attached and main cable running though it though. I am able to move it a bit without removing everything from the wall.

Thanks again for all of the help!

 

[LOW1]

I don't think they can come out the top of the panel in Canada. There's a barrier inside to separate the top and bottom halves.

In our Ontario boathouse the power comes in underground and into the sub panel from the bottom. Lines then go out the top and up to the attic. It’s a square d homeline panel I think identical to what we can get in the u.s. Other provinces may differ.

 

[sparky 1971]

I didn't word my post very well. I assumed the barrier was on top since the OP wanted to come out of the side.

 

[klassenl]

You can drill holes next to the panel. Pass your wire through the plywood and plastic and run wherever you want from there. This is the quickest and your inspector will be OK with it. The rules for exposed NMD are less stringent when running into the panel like this.

Coming from Alberta.

 

[Duke74]

In Alberta Canada. We run the nmd90 down the studs behind the plywood backboard. We drill holes in the plywood close to the knockouts in the side of the panel, and run the cables out through those holes. That way the cables are only exposed the short distance between the plywood holes and where they enter the panel. If you plan out where to drill the holes, the finished job looks pretty neat.