Subpanel checklist

davehoDecember 7, 2009

I'll be installing a subpanel. I just want to verify I have all my information correct. The subpanel will be a 125A main lug load center, 12 spaces. It'll be fed by a 100A breaker in the main panel. Wire will be #3 copper THHN for the hots & neutral, #8 copper THHN for the ground. This will be run in 1 1/2" PVC conduit. Ground & neutral in the sub panel unbonded. The main panel & the sub panel are both in the basement about 5 ft from each other.

Sound good?

Thanks.

-Dave

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Ron Natalie

1/2" PVC isn't going to hold more than 1 #3 wire.
You're going to have to go up to at least 1 1/4".
Given it's only 5' I'd put 2" and make the job of pulling easier.

    Bookmark   December 7, 2009 at 10:35AM
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terribletom

Sooner or later it happens to all of us.

Uh, Ron, I think it's time to put on the ol' spectacles. The OP dude-in-question said one-and-a-half (i.e., 1 1/2") conduit, which oughta work out just fine and dandy.

Sounds like a plan, Dave.

    Bookmark   December 7, 2009 at 8:07PM
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Ron Natalie

Oops...missed it in the line break. 1 1/4 would be the minimum. 1 1/2 is fine.

    Bookmark   December 7, 2009 at 8:22PM
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daveho

Thanks for the verification guys. I've got a couple of follow up questions.

My main panel is a Westinghouse/Bryant, that company no longer exists. They were bought by Cutler Hammer. As far as I can tell, Cutler Hammer type BR breakers are the approved substitution. Correct? Here's the interesting thing, with the exception of the main 200A Bryant & one 15A Challenger breaker, all the other breakers are ITE or Siemens type QP. Most were installed at the time the house was built, a couple by me. They appear identical to the CH type BR breakers, but as far as I can determine, are not officially approved for this panel. Is there a real saftey issue here? They passed inspection & have been working fine for years.

Second, any preference for brand of the load center to be used as the sub-panel? I was leaning toward Siemens, before I discovered my main panel should be using Cutler Hammer type BR breakers. Now I'm thinking maybe go with a CH type BR load center to keep the main & sub panel breakers interchangeable. However, I'm kind of under the impression that the Siemens load centers & breakers are of slightly better quality than the Cutler Hammer. Thoughts?

Thanks!

-Dave

    Bookmark   December 7, 2009 at 10:21PM
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Ron Natalie

Correct, as you may have guessed the BR-series panels and breakers are the Bryant ones. While there were a lot of "it will just work" substitutions in these panels, as far as UL is concerned (and hence the code) you're supposed to use the listed breakers.

Using another BR panel might not be a bad idea. Breakers are often a local convention and hence I'd tend to use what the local hardware/homecenters. For example, here it's almost exclusively Square D and GE. You won't even find a CH panel (and darn few CH breakers) at the home centers while up in NJ it's sort of the opposite, everything is CH and you won't even see a GE breaker.

While you can get panels and breakers for any line in most real electrical supply stores, you're going to get gouged typically if you aren't in the trade, and they're not open typically on nights and weekends when you may feel the need to get a part in your home panel.

    Bookmark   December 8, 2009 at 7:47AM
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daveho

Thanks. I've got one more question. Is there a "best" place in the main panel to put the 100A breaker that will feed the subpanel? On the few installations I've seen, I usually see the breaker that feeds the subpanel positioned as close to the main as possible on the buss bars. Is there a good reason for this or just convention?

Thanks.

-Dave

    Bookmark   December 11, 2009 at 10:56AM
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spencer_electrician

wherever you want and that allows the wires to bend properly and land to the breaker.

    Bookmark   December 11, 2009 at 11:00AM
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fotostat

What are you using to drill the panels? If you use a hole saw get an 1 7/8".

    Bookmark   December 11, 2009 at 10:26PM
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Ron Natalie

I'd use a punch, but I get a employee discount on greenlee.

    Bookmark   December 12, 2009 at 10:52AM
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fotostat

He doesn't seem like an electrician so why waste the money on a KO set?

    Bookmark   December 12, 2009 at 2:44PM
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daveho

My main panel already has suitable sized knockouts on the side of the panel where I intend to feed the sub from. I don't think I'll have a problem placing the breaker anywhere.

I think you guys have covered all my questions. I'll be tackling this bewtween Christmas & New Years.

Thanks!

-Dave

    Bookmark   December 14, 2009 at 8:56AM
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