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Discussion Starter · #1 · (Edited)
Hello all,
A future project I have in mind is to rewire my detached garage. I am far from ready for this project and plan to devote a very long time of study to it before trying. This garage is very old and the wiring was done without much regard for code and/or safety unfortunately. The walls are all unfinished, so I have open studs which is helpful once the project begins.

Currently, there is 14/2 wire running from the sub-panel to all the various circuits, both lights and outlets. The wire is stapled to the studs in various places, but not passed through holes drilled in the studs. Instead the wire is just wrapped around the front of the stud as needed. It's high enough that I don't see an imminent risk of something hitting or damaging it, but I definitely want to do it better.

I have no plans for the foreseeable future to finish out the walls, so my wiring would still be exposed even though I do plan it less haphazardly than the current install. I understand that regular Romex style wiring shouldn't be run through conduit, but I'm unsure how else to keep it from being exposed. I definitely can't afford to run MC cable through the whole garage. I'd like to hear your thoughts on wiring this garage safely and cost effectively. What wire would best serve my needs?

I plan to power at least 4 and up to 6 overhead LED light fixtures as well as have around 8 110 outlets. There is an existing 220 outlet as well that I don't currently need, but I plan to keep it for "just in case" reasons. The existing subpanel is an older 100 amp Square D QO box and I don't anticipate needing to change it. Sorry for the long post. All replies will be much appreciated.
 

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Discussion Starter · #2 ·
Been doing some reading since my previous post. Looks like perhaps the answer for the wiring is to run THHN cable through EMT. Does that sound right?
 

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Naildriver
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Largely it will depend on the OCP in the house and the wiring to the sub panel. Can you fill us in on that? From the sub panel (which will need grounding, incidentally) you can wire your circuits at will, basically with new cabling and receptacles/switches/lighting. With the cover removed from the sub panel, can you post a picture if the innards of the panel so we can see what you are seeing. The cabling/wire from the house will need to be a 4 wire set up, too, and if it is ancient, you may only have a 3 wire system.
 

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Discussion Starter · #4 ·
Thanks Larry. My meter and main disconnect are located on a pole outside my home. This panel is only a few years old and was installed by an electrician I trust. There is a separate line that runs underground to the detached garage from the disconnect panel, so I can turn off the garage without turning off the house. I'll go out and get some pictures later and get them posted.
 

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A "Handy Husband"
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You can run NM in conduit if you are in US. If NM is run in stud bays and not on face of stud it does not need further protection. Drill thru studs and top plate.

Sent from my Moto E (4) Plus using Tapatalk
 

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Naildriver
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KenDP, that changes things a little, for the better. It will, now, depend on the wiring from that main panel on the pole to the garage. Size and number of conductors, and how it is protected (conduit, direct burial, etc.)
 

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Discussion Starter · #7 ·
You can run NM in conduit if you are in US. If NM is run in stud bays and not on face of stud it does not need further protection. Drill thru studs and top plate.

Sent from my Moto E (4) Plus using Tapatalk
Great to know, thank you! That will definitely make things easier than I thought.
 

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Discussion Starter · #8 ·
KenDP, that changes things a little, for the better. It will, now, depend on the wiring from that main panel on the pole to the garage. Size and number of conductors, and how it is protected (conduit, direct burial, etc.)
I went out and took a closer look. Turns out there is not a separate disconnect from the garage out there. I would have sworn that was the case, but alas...
Unfortunately, I haven't found a disconnect upstream from the garage subpanel, so not sure what I'll have to do to shut it off. That's going to take a little work to investigate.
I went out and killed the breakers to everything in the garage subpanel and took out an outlet and the only light switch. What a mess. The light switch is wired opposite how you would expect: it's run with the neutral wires to both screws and the black hot wire is wire nutted back in the box like you'd expect the neutral to be. The one outlet I took out has the white and black wires run to the opposite screws than they should be.
I carefully took the face off the subpanel. Looks like whoever wired this ran neutrals and grounds both to the neutral bar. There is no ground bar. There is a ground rod outside behind the garage that I could use, but it currently has nothing attached to it.
I'll be posting some pictures soon. Gotta get them transferred over from my phone.
 

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Discussion Starter · #9 ·
I forgot to mention in my previous post, the cable coming into the garage sub-panel is 3-wire. Two hots and a neutral. Not sure what size it is. There is no ground.
 

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Those wires should have been in conduit.
 

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Discussion Starter · #12 · (Edited)
So, this is the complete novice in me coming through. Since there is no ground wire going back from the sub panel to the main panel, can a ground bar be put in the sub panel and a wire run from there to a buried ground rod behind the garage? Questions like this show you why I'm not just diving in and doing this work. I want to learn as much as I can before taking action. The wire looks in the picture above like it is 2-2-4, though I'm not absolutely certain.
 

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A 3 wire feed is allowed to continue in use.. If a new feeder is installed it should should be 4 wires.

Either way the panel will need a grounding system.
 
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A "Handy Husband"
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So, this is the complete novice in me coming through. Since there is no ground wire going back from the sub panel to the main panel, can a ground bar be put in the sub panel and a wire run from there to a buried ground rod behind the garage? Questions like this show you why I'm not just diving in and doing this work. I want to learn as much as I can before taking action. The wire looks in the picture above like it is 2-2-4, though I'm not absolutely certain.
With a grandfathered 3 wire feed the ground and neutral must be bonded. You still need the ground rods.

Sent from my RCT6A03W13E using Tapatalk
 

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Discussion Starter · #16 · (Edited)
With a grandfathered 3 wire feed the ground and neutral must be bonded. You still need the ground rods.

Sent from my RCT6A03W13E using Tapatalk
Ok, I'm still not completely understanding. Does that mean I can connect this subpanel to it's own buried ground rod behind the garage? If so, should I add a ground bar to the subpanel to connect the rod to? Sorry if I'm being dumb. I'm just not completely understanding the answer.
 
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