What is the best way to wire this?

RST · 08-17-2009, 11:32 PM

Hi folks,

Working on rewiring my oversized 3-car garage. 2 issues: 1) the previous owner mucked it up badly so I need to address all of his problems, and 2) I am going from 1 all-purpose circuit to 1 lighting and 3 receptacle circuits (for now, more in the future as I create a workshop).

I'd like your opinion about how to wire the following stud bay. Please see my pictures below. Currently, a 14/3 (or 12/3? need to check) wire enters from the top right; this feeds a 3-way light switch (on the right) which controls the overhead light. A 12/2 wire enters from the top center and feeds the light switch on the left; this controls an outside light (you can see the wire running into the next stud bay for that light). The 12/2 wire comes from an upstream receptacle.

My plan is to do the following: 1) Put the upstream receptacle on a new circuit and upgrade it to a GFCI. 2) Add an outdoor receptacle on the wall below the light switches. 3) Bring in a 10/2 wire from the left side to feed two downstream receptacles which will give them GFCI protection. Note: the previous owner put in the wire, he never even uncoiled it properly so I have yards and yards of it to work with.

What is the best way to accomplish this? Add a junction box somewhere? Use the outdoor receptacle box as a junction box? Upgrade the box with the switches? I came up with a bunch of answers, but I'm wondering what solution a professional (or another amateur) would recommend.

Two additional notes: I have no intention of finishing that part of the garage, and there is almost no slack in the 12/2 wire that comes from the upstream receptacle.

Thanks,
Robert

BCSparkyGirl · 08-18-2009, 12:47 AM

It all depends on you box fill req. with your code. I have a tendancy for overkill a little bit, so, you could put a j/b above your switches, and splice all your stuff in there, as you said there wasn't a whole lot of slack on the one wire, (this is assuming you do not wish to replace any of the existing runs) and I always like to have a litle extra to play with. Then you could do all your splicing in there and just run out of it to al your lts/sw's/recp's......or you can just make sure all your boxes are sized large enough for x amount of splices, and enough room for the devices in it. I can quote you CEC code req, but this will not help you in the states. It for the most part is common sense stuff, and it sounds like you already know roughly how you want to do it. There is more than one way to do it in regards to boxes. Just make sure any J/B's you put in are able to be accessed after the drywall goes up.

Stubbie · 08-18-2009, 12:34 PM

Is there a sub-panel in the garage? Is it detached or attached to the house? If attached are you going to bring your branch circuits from the house main panel?

If your going to rewire and you want receptacle circuits separate from lights and you only want one lighting branch circuit then find the best existing point to break the existing receptacles off the lights. You only have two lights correct? One Inside and One outside. One 15 amp branch circuit wired with 14 awg romex will supply 1800 watts of lights. I would mix in some fluorescents as well as incandescent.

I don't see anything goofy about the wiring in your picture other than routing and support of the cables. Make your receptacle circuits 20 amp 12 awg romex. Do not mix wire sizes!!

Do not make junction boxes....

Make all transitions in existing or new device boxes or ceiling boxes. If you worry about having enough existing wire your going to botch it up. You say you have lots of extra wire. That's great but be sure you don't handcuff yourself to that amount of wire.

As for that switch box your showing, very simply, you need to get the receptacle feed to that switch box changed to a lighting branch circuit. It may be possible to reroute that romex to the receptacle you want under neath that switch box, Then bring another power feed to the switch box that is part of a lighting branch circuit for the outside light. The 3 way can stay as is but at the second 3 way switch you will need to join it with the same power feed you are using for the outside light. Doesn't have to be that way but keeps two power sources from being in the same switch box.

If you can pan out with a picture and give us the total layout of the area we can be more accurate in advice.

My personal opinion is if your shooting towards a workshop and there is no sub-panel located in the garage I'd install one now and wire from it.

RST · 08-18-2009, 03:21 PM

Hi Stubbie,

I installed a subpanel last month, it was my old home panel so I have lots of breakers and space for circuits. The subpanel is probably about 20 feet to the right of the space in question. The garage has 3 areas, a parking area with 2 bays and a small storage area behind (where the switches are) and another parking area with 1 bay added later. I don't need the 3rd bay, I plan to use that as a large workshop area/entertainment area/TBD. (Most houses in my neighborhood are lucky to have a 2 car garage!)

Two questions:
1) Is it a code violation or just bad practice to have the switches on two different circuits? Seems like it would be a pain to run a new wire from a light fixture just to put the switch for the outdoor light on the same lighting circuit and then to run another new wire for the outlet. But it would make it simple to wire the receptacle, and there would be no need at all for a junction box.
2) Is it OK to use 10 and 12 gauge wire on the same 20A receptacle circuit? The previous owner ran 10 everywhere and seems a waste to pitch it and run all new 12. What about using 12 for pigtails since 10 is a pain to get around screw terminals? (I know not to mix 14 and 12 on a 20A circuit.)

Thanks,
RST

P.S. All of the wiring has been done in the "ceiling" with "drop downs" for receptacles. Would it be OK to run the cable through the studs to connect the receptacles? Or would that subject it to damage since the garage is unfinished?

Stubbie · 08-18-2009, 05:47 PM

Quote:

2) Is it OK to use 10 and 12 gauge wire on the same 20A receptacle circuit? The previous owner ran 10 everywhere and seems a waste to pitch it and run all new 12. What about using 12 for pigtails since 10 is a pain to get around screw terminals? (I know not to mix 14 and 12 on a 20A circuit.

Now I know why you said the wiring was mucked up. That 10 awg shouldn't be there...he must have had some free 10 from somewhere. If it were me I'd make some dedicated receptacle circuits with it for shop tools.

Yes you can pigtail it with 12 as long as you use a 20 amp breaker. Again if it were me I'd use the 10 to make a welder circuit with it and maybe single outlet space heating or fixed heating branch circuits maybe a few machine tool circuits. In other words use it where it makes sense.

The problem I have with what exists is it appears you have possibly 3 wire sizes with one general purpose branch circuit. Screw that!!! Makes you look like you need a stupid hat , the guy that did that sure did....

I can only tell you that cost savings only goes so far with me. I'd much rather have something that made sense and shows I knew what I was doing rather than wire that is a hundred miles overkill and out of place.

You mentioned one thing that caught my ear and that is you want a shop some day and you do not plan on finishing the garage. So this sorta gets us around to talking about the physical protection of the wiring since you have open wall stud cavities. So I just tell you if I wired this garage it would be either all EMT and thhn individual wires with metal device and fixture boxes or I'd drop from the joists or trusses with sleeves of EMT to the switches and receptacles running my cables in those protective sleeves.

At any rate back to your switch box. I'd wire it the way you want period. Wire is not that expensive. But if you notice there isn't any load amps involved with just that one light and even if the other light was on that circuit. After all everything is on one branch circuit correct??

So the simpliest thing would be to use the switch box as a jb and just splice to the power feed coming into that switch box for the outside light with a short piece of romex then down to a gfci receptacle for the outside. This doesn't get the lights on their own circuit but I really see no problem doing it that way.

Again though I'd almost think you should start from scatch use what wire you can that exists and get the 10 awg out of there or to special outlets as I mentioned before. Get the same size wire for your branch circuits ...14 awg for lights and 12 awg for receptacles (gfci protected) and wire it right....you will be much happier.

As for physical protection that is up to an inspector to decide but I can tell that many inspectors are going to require you to drop from the ceiling with a listed protective sleeve of some kind. That is almost always going to be EMT if I'm doing the job.

Best I can do, I just don't think I'm going to get any mileage out of trying to find easy ways to work with what exists. Others here will likely have suggestions so keep your screen tuned.....

RST · 08-18-2009, 08:25 PM

Thanks, that clears up a lot for me. I will rewire the other owner's work with 12 gauge. The one circuit that I already started with (his) 10 gauge I will finish with 10 gauge for consistency. Then I'll save the rest of the 10 gauge for future use in case I put in some large equipment someday. I'm still interested in what others have to say, so feel free to chime in guys.

Here are some pictures of another area that needs work.

I count at least 4 obvious NEC violations and another bunch of things that are technically correct but bad practice. (I installed the plastic "in use" cover on the outlet, it is to keep my toddler out. Normally it's shut.)

My home inspector completely missed all of the wiring problems in the garage.

While I wouldn't expect him to catch every problem, the open splice (with a partially bare wire) is especially egregious. (He also missed some other non-electrical defects with the house, I'm not using him again.)

RST

joed · 08-18-2009, 10:47 PM

I would not use the #10 for normal duplex circuits. To hard to work with. Creates box fill issues.

InPhase277 · 08-18-2009, 11:49 PM

That looks like hammered dog crap.

BCSparkyGirl · 08-19-2009, 12:29 AM

good god, I wish I had taken pics of my brother in laws basement I just rewired........made that pic look professional. I pulled down the drywalll in one room and there were 17 open air splices in one room, and the spliced were just shoved under the wire nuts, not twisted beforehand, so one would just....oh fall out.....sparksparkspark everywhere.......my god it was awful. And I am positive I did not find ALL the ****, but redoing the entire house was not an option, so I just hope it does not burn down, how it hasn't to this point is bloody amazing.