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Old 07-19-2018, 03:51 PM   #1
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Need advice for 2" conduit connections to detached garage


I have a detached garage ~15ft from my house, which is currently fed by a buried 15A cable.

I want to remove that and run the following:
- 4x THHN 6AWG (for 50A circuit)
- 6x THHN 12AWG (for two 20A circuits)

My plan is to dig and run a 2" PVC conduit (18-24" deep) using LB conduit connections at both the house and garage.

Inside my house I have Romex cables for the 50A and two 20A circuits that will need to be converted to THHN before exit.

My plan is:

- Have large junction box inside the house, at the exit point, and splice all the wires inside. I'm planning on using "Polaris"-type insulated splicers for the 50A connections and wire nuts for the 20A.

My questions are:

1. Does the above sound correct so far?

2. My real point of confusion is how do I mate the 2" PVC pipe with a junction box? How is this normally accomplished? I assume some type of reducer system is needed?

- What kind of reducer fitting?
- What fittings would be needed to transfer to a foot of flexible conduit?

For all the splicing on the house side, should I buy a 4x4 PVC box like this and drill my own hole? Reduce to what size? Transfer from PVC to flexible conduit?

Any advice would be much appreciated. Thank you.
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Old 07-19-2018, 03:56 PM   #2
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Re: Need advice for 2" conduit connections to detached garage


Did you consider setting a 60A sub panel?

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Old 07-19-2018, 04:08 PM   #3
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Re: Need advice for 2" conduit connections to detached garage


Yes, I even considered adding a 100A subpanel, but my basement is semi-finished and running a new connection from my main box (wrong side of the house) would be absolutely painful, plus, by only running individual circuits I can also avoid the 8-ft grounding rod requirements.

My main point of confusion is determining which parts are required to mate 2" PVC pipe to junction boxes.
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Old 07-19-2018, 04:17 PM   #4
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Re: Need advice for 2" conduit connections to detached garage


Quote:
I want to remove that and run the following:
- 4x THHN 6AWG (for 50A circuit)
- 6x THHN 12AWG (for two 20A circuits)
Not allowed by code. Only one circuit to a detached building. You will need to run a 60 or 100 amp circuit and install a sub panel.
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Old 07-19-2018, 04:29 PM   #5
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Re: Need advice for 2" conduit connections to detached garage


Run the feeder.in a.1" /conduit.and set.a.60 amp subpanel.
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Old 07-19-2018, 04:53 PM   #6
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Re: Need advice for 2" conduit connections to detached garage


Only one circuit may be run to a detached structure, by code. You'll need to run a 4-wire feeder from your main panel and set a subpanel at the garage, with the required grounding electrodes (not too hard to achieve). You could run the feeder conduit along the exterior of the house way down near the ground. That may be easier than going through the finished basement.

2" PVC connects to junction boxes using a threaded adapter with lock nuts. You'll have to make the holes in the boxes yourself, with a hole saw or punch. Most panels have KO's big enough for 2" pipe though.
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Old 07-19-2018, 05:32 PM   #7
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Re: Need advice for 2" conduit connections to detached garage


Thanks all. I wasn't aware of the code about running more than one circuit to a detached building.

Looks like the only option is a subpanel.

It sounds like for 100A sub-panel I can run 3/3/3/8 THHN Cu in a 1 1/4" PVC conduit?
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Old 07-19-2018, 06:55 PM   #8
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Re: Need advice for 2" conduit connections to detached garage


You need to use wet rated THWN. Most wires are dual rated though. Just make sure before you buy it that is has the THWN rating.
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Old 07-21-2018, 05:01 PM   #9
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Re: Need advice for 2" conduit connections to detached garage


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Originally Posted by Alketi View Post
Thanks all. I wasn't aware of the code about running more than one circuit to a detached building.

Looks like the only option is a subpanel.

It sounds like for 100A sub-panel I can run 3/3/3/8 THHN Cu in a 1 1/4" PVC conduit?
THWN, but yeah. Although you may want to use #2 aluminum (XHHW or similar) instead. It'll be cheaper. 2" conduit is definitely a good idea. Conduit is cheap and larger is easier to pull through.
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