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Going from in-the-wall main panel to surface mounted sub panel in garage

Going from in-the-wall main panel to surface mounted sub panel in garage

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  #1  
Old 09-16-13, 11:43 AM
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Going from in-the-wall main panel to surface mounted sub panel in garage

I need a few more outlets in an attached garage. Two of them are 220V with 20 and 23 amp requirements and I will add a couple of 110v 20amp circuits for hand tools, etc. I plan to install 20 and 30 amp breakers in the subpanel for the 220V loads (machine and welder, can't use at the same time) and run the subpanel from a 60 amp breaker in the main panel.

My main panel is a Square D QO panel so I bought a 20 space QO panel for the sub. The main panel is in the garage wall, but I want to mount the sub on the surface so I can wire anything else in the garage (more easily) with conduit. I plan to install the 220V outlets for the machine and welder immediately below the subpanel in a suface mounted outlet box with a close-nipple length PVC conduit for the #12 (for 20 amp) and #8 wire (for the 30amp).

My main question is how to run the 6/3G NM wire from the main panel in the wall to the surface mounted sub. I want to install the sub panel right next to the main panel so that is the only area I will have to keep clear in the shop. The machine sits to the left and the small welder will be to the right near the big garage door. The total length of the 6/3G wire will be about 5' or so. I intended to come out the bottom of the main panel (in the wall), go through the one stud separating the panel locations, and into the back of the sub so I do not need to do any conduit or transitioning into the surface mounted subpanel. I had planned to run the wire into the back of the subpanel in the lower right corner and run up the right side to the main lugs. Can I do that?

I would appreciate any other suggestions or things I have overlooked. I am trying to keep this as simple as possible.

Thanks.
 
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  #2  
Old 09-16-13, 04:11 PM
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Two of them are 220V with 20 and 23 amp requirements and I will add a couple of 110v 20amp circuits for hand tools, etc. I plan to install 20 and 30 amp breakers
The residential single phase voltage would be 120/240 so these would be 240 volt circuits, not 220. both 20 and 23 amp requirements would call for 30 amp breakers.

I will add a couple of 110v 20amp circuits for hand tools
These would be 20 amp 120 volt circuits. The 120 volt receptacles will require GFCI protection.

The total length of the 6/3G wire will be about 5' or so. I intended to come out the bottom of the main panel (in the wall), go through the one stud separating the panel locations, and into the back of the sub
That would work, but will require a lot of drywall repair, I wouldn't do it that way. I'd notch the drywall at the bottom of that main panel and use 1" EMT from there to the bottom of the new subpanel; the conduit would be surface mounted except for an offset to reach into the notch and access the bottom of the main panel. For the subpanel I'd use a MLO panel inverted to be bottom fed.
 
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Old 09-16-13, 04:14 PM
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I use a deep junction box so, I have enough to go inside the wall and enough sticking out for conduit to come out of.

Cut the wall the size of the box, notch the stud and put a rigid nipple between the box and the panel.

Here is a pic of how I did it.
Name:  deep jb.jpg
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Old 09-16-13, 04:21 PM
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Here's another one. Notice the panel is on the right.
Name:  deeper JB.jpg
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  #5  
Old 09-16-13, 05:27 PM
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CasualJoe,

I already cut the drywall below the main panel to make sure what was under the panel behind the wall. Nothing but a ground wire. I also cut on the subpanel side, but will mount plywood over that to fasten the subpanel, outlets, and conduit to. I have work to do!

The twenty amp circuit is for a 9 or so amp load for the machine. The manufacturer suggests a 20 amp.

I did plan to use GFCI for the 120 volt circuits. I want to put multiple receptacles in one box and feed from the GFCI to the other receptacles in the multi-box.

If I use a conduit LB fitting, do I just fasten it to the plywood and it just has to have the back point through the sheetrock? Can I use the romex type 6-3G wire I have and run it up into the LB fitting, through a short length of conduit, and into the subpanel?

Wirenut,

How deep is the box you recommend? I cannot find one like that. Will it have knockouts inside the wall and outside the wall for attaching the conduit or will I have to make holes for them? Can I get that in PVC so I can use PVC conduit?

Thanks for the help.
 
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Old 09-17-13, 08:16 AM
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The twenty amp circuit is for a 9 or so amp load for the machine. The manufacturer suggests a 20 amp.
In that case, yes, use a 20 amp circuit.

If I use a conduit LB fitting, do I just fasten it to the plywood and it just has to have the back point through the sheetrock? Can I use the romex type 6-3G wire I have and run it up into the LB fitting, through a short length of conduit, and into the subpanel?
I am not sure how an LB condulet would help is this installation. You'll have a very difficult time getting 6-3 NM B cable through an LB fitting, that isn't what NM cable is for nor is it a normal installtion to do so. When using conduit and condulet fittings, individual conductors such as THHN/THWN wire should be used.

I already cut the drywall below the main panel to make sure what was under the panel behind the wall. Nothing but a ground wire. I also cut on the subpanel side, but will mount plywood over that to fasten the subpanel, outlets, and conduit to.
Since the drywall has already been removed, why don't you just come out of the bottom of the main panel, go through a drilled hole in the stud and enter the subpanel through a hole in the lower right back of the subpanel. You wouldn't need any conduit, just cable connectors (probably 1" connectors). I'd still invert the subpanel for a bottom feed.
 
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Old 09-17-13, 11:49 AM
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I plan to install 20 and 30 amp breakers in the subpanel for the 220V loads (machine and welder, can't use at the same time)
Not that it matters, but why not? Just curious.

Originally Posted by CasualJoe
I am not sure how an LB condulet would help is this installation.
I agree.

Originally Posted by CasualJoe
Since the drywall has already been removed, why don't you just come out of the bottom of the main panel, go through a drilled hole in the stud and enter the subpanel through a hole in the lower right back of the subpanel. You wouldn't need any conduit, just cable connectors (probably 1" connectors). I'd still invert the subpanel for a bottom feed.
In order to get your 6-3/G cable into the back of your subpanel within the depth of the stud bay, you'll probably want to use a 90[SUP]o[/SUP] connector on that end. Because those lay tight to the surface of the enclosure, it's usually necessary to notch the wall finish material when coming in through the back. For that reason, I'd plan on bringing the feed in near the top.
 
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Old 09-17-13, 12:46 PM
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Thanks for the input. I will plan to come in the back and will use a 90 degree connector.

I plan to install 20 and 30 amp breakers in the subpanel for the 220V loads (machine and welder, can't use at the same time) Not that it matters, but why not? Just curious.
It is only me working in there and I can only run the machine or weld.
 
  #9  
Old 09-17-13, 12:51 PM
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I plan to install 20 and 30 amp breakers in the subpanel for the 220V loads (machine and welder, can't use at the same time)
Originally Posted by Nashkat1
Not that it matters, but why not? Just curious.
It is only me working in there and I can only run the machine or weld.
OK. I just wondered because the panel is good for both at the same time.
 
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