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Old 05-15-2010, 10:44 AM   #1
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Looking for critiques of my raceway plan


A diagram is attached. I'm planning to replace the lighting and receptacle circuits in my garage using EMT as surface raceways. The garage is 750 SF and had old recessed incandescent fixtures which I had to remove when I replaced the ceiling. There is a subpanel in the garage with a 50-amp breaker at the main.

I tried to keep the total number of splice points and j-boxes to a minimum. Since it's just 2-D, I couldn't really show anything but the ceiling view, but of course there are vertical runs descending for the receptacle and switches. There are two separate circuits for receptacles--one for 15 amp and one for 20 amp.

This was my first try, but I'd like to know if anyone here has any constructive criticism.

Thanks.
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Last edited by dave11; 05-15-2010 at 10:48 AM.
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Old 05-15-2010, 01:33 PM   #2
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It's not bad. I'd put a J-box right above the panel and keep the ones you have on the top side of the I-beam. I'd also recommend putting a J-box on the ceiling and whipping to the fixtures. That way you'd avoid pulling your power circuit through the fixtures. Unless your fixtures are rated for this, it's a no-no. Not bad first time out, though.
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Old 05-15-2010, 01:58 PM   #3
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It's not bad. I'd put a J-box right above the panel and keep the ones you have on the top side of the I-beam. I'd also recommend putting a J-box on the ceiling and whipping to the fixtures. That way you'd avoid pulling your power circuit through the fixtures. Unless your fixtures are rated for this, it's a no-no. Not bad first time out, though.
Hi Goose. Thanks for the input. Originally I had a separate conduit for all the lights, but then I realized I could skip one if I ran the door opener through the light. The gfci was an afterthought. I would guess it would be a potential heat issue within the fixture? I guess I assumed that since the fluoros have knock-outs at both ends, they were allowed to be wired in line, and so a long enough line of them could have 15 amps running through the fixtures. But now I see 15 amp + 15 amp = 30 amp. Duh.

Maybe I was too focused on keeping the splices and j-boxes to a minimum.

Also, when I drew out the wiring, I found that in the first j-box, there ends up being 6 neutrals to splice together. There are three separate circuits running through the raceways, with a total of 5 legs, that need to splice to the neutral coming from the subpanel. Makes me wonder whether I should change the design (ie. more boxes/splices) or use something like a terminal block?

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Old 05-15-2010, 02:58 PM   #4
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You cannot share a neutral with that many circuits unless properly sized.

In your case, if 3 circuits are ran, you would need at least two neutrals.
Black, Red, White and Black, White for example.
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Old 05-15-2010, 03:28 PM   #5
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You cannot share a neutral with that many circuits unless properly sized.

In your case, if 3 circuits are ran, you would need at least two neutrals.
Black, Red, White and Black, White for example.
Each circuit has its own neutral. The five-way splice would be on a single circuit, the one carrying the overhead lights and the door opener. At box 1, there would be the 14 g neutral from the panel, then a neutral for all three conduit legs that run the lights. This is four wires so far, but since the lights will draw at most 3 amps, on a dedicated 15 amp circuit, I was going to add the garage door opener wired into that circuit, but unswitched. So that leg would be anoither neutral, total of five wires coming together at box 1.

I realize now I should remove the gfci receptacle (or any receptacle) from that leg to the door opener.

No part of the circuit would ever carry more than 15 amps. But a five-way splice seems questionable to me. So I'm not sure if I should add more splices and boxes further out, to avoid it.
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Old 05-16-2010, 03:06 AM   #6
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There is nothing out of the ordinary about a 5 wire splice. I would reconsider networking your neutrals. That is to say, run a multiwire branch circuit. Two hots on opposite phases can share a neutral legally. There is no compelling reason not to do so. In fact, it'll mean less wire used, more room in the pipe and money saved.

If you can avoid running the power through the light fixtures, all the better.
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Old 05-16-2010, 02:21 PM   #7
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There is nothing out of the ordinary about a 5 wire splice. I would reconsider networking your neutrals. That is to say, run a multiwire branch circuit. Two hots on opposite phases can share a neutral legally. There is no compelling reason not to do so. In fact, it'll mean less wire used, more room in the pipe and money saved.

If you can avoid running the power through the light fixtures, all the better.
Well, I had considered shared neutrals at first, but on this site and others, it was pointed out that there are potential problems that way, such as the loss of the neutral, leaving 240 volts in the affected circuits. Or the chance that someone else working on the lines might not realize the shared neutral was there, and might get shocked, though if I put a DPST breaker in the subpanel, with the circuits on opposite phases, that should never happen, unless someone changes the subpanel wiring. But someone also suggested a problem with a shared neutral and fluorescent lights, which I was planning on using in the garage. So even though many pro electricians use shared neutrals, I thought I'd avoid any possible problem and do it with separate neutrals.
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