Subpanel Details


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Old 05-30-14, 07:48 PM
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Subpanel Details

Installing a subpanel in a detached garage. I have most of it planned out, but wanted to confirm with the experts.

8/3 w/ground UF wire on a 40A breaker. Buried 24" deep. So far so good?

8ga insulated copper to an 8' 1/2" ground rod with acorn clamp.

I'm wondering if I'll be able to feed this 8/3 + 8ga ground wire through the existing 3/4" PVC and LB sleeve at the house and garage or if I'll have to swap it out with 1" PVC to get it to fit. They are only about 18" long, just to sleeve the wire as it comes up above ground.

Thanks in advance for everyone's help!

-Mike
 
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Old 05-30-14, 09:09 PM
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I don't think that UF cable will fit in 3/4" PVC. Even if it did.... you'd never be able to work it thru an LB.
 
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Old 05-31-14, 02:33 AM
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If using a copper clad ground rod , must be at least 5/8" x 8' , At least that is what we have always used and I am pretty sure it meets NEC .

However , I would have to go back and look it up , to see if the ground rod is indicated ?

What is the distance to the detached garage ? If it is not very far , I would run PVC all the way . If it is quite a ways , I would go up at least 1 wire size for voltage drop .

God bless
Wyr
 
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Old 05-31-14, 04:29 AM
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If the garage is served by a feeder and not a MWBC or a single circuit it needs a rod.
 
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Old 05-31-14, 11:23 AM
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Thanks for the feedback. It's about 20' between the house and garage, about a 50' run panel to panel. I've considered running PVC the whole way, but it's sort of a pain once it gets into the house. I could of course transition to NM-B. Maybe that's the way I'll go instead of fighting with UF.

Is 8ga still required for THWN in conduit? And a 10ga ground?

Thanks again!
-Mike
 
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Old 05-31-14, 04:29 PM
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Is 8ga still required for THWN in conduit? And a 10ga ground?
Yes, and yes. you also only need to dig 18" if you use PVC.
 
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Old 06-01-14, 05:35 AM
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Best I remember , by NEC , you only have to bury Galvanized Rigid Conduit 6" ? If you went that way ?

More $$$ but less digging .

But it has been a LONG time since I looked that up . Our local / city code requires 24" , no matter what , so it is a non issue .

The way I would do it is run at least 1" PVC ( in case I ever needed more power & needed to re-pull larger wire ) all the way . Stub up with GRC ( tape the below ground GRC with PVC tape , like Scotch Wrap , for corrosion protection ) and use an " LB " to enter the panels , if necessary .

And pull THHN . The new wire with Super Slick coating is easier to pull . But I would still use lots of wire lube when pulling the wire . Outside / out doors , I like Yellow 77 . When inside , I like the clear lubes . No staining in case of a spill .

God bless
Wyr
 
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Old 06-01-14, 05:58 AM
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Sounds like a plan, thank you all for your help! I'll let you know how it all turns out!

-Mike
 
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Old 06-01-14, 06:41 AM
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In my experience lube is rarely needed if you install the conduit correctly. Yellow 77 turns into a paste/glue when it dries out and it would be very hard to get the wire out later if needed.
 
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Old 06-02-14, 02:05 AM
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The original Yellow 77 is a wax base . You may be right about the water based version ?

Hard to screw up PVC in a ditch , as long as you keep the inside clean and do not use more than 360 degrees of bend . And use factory made bends ( 90's , 45's & maybe 30's ) .

But , that is another reason I recommended 1" in stead of 3/4 " conduit . And , wire lube is cheap insurance when it comes time to pull the wire .

God bless
Wyr
 
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Old 06-02-14, 04:46 PM
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The original Yellow 77 is a wax base . You may be right about the water based version ?
I think the stuff I have seen was the Wax based stuff. I'm betting the water based might be better. I still have only used lube on one job in 12 years. However, that was with PVC.
 
 

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