[ptb]

installing a 100 amp indoor sub panel to power up a shed and get outdoor power to backyard. Running 3 new circuits. I am not wanting to run (3) 3/4" LB conduit body and pvc pipe runs out of the wall and into my trench. Rather run a single 1" LB conduit body and pipe out of the wall and into the trench containing all 3 new circuits ( (9) THWN 12 awg wires). Then run each individual circuit in its own conduit raceway to its location.... so my question is how to do that without having exposed THWN wire briefly exposed to the trench before it enters the individual conduit raceways. They don't appear to make a underground box or junction that has a 1" entry and (3) 3/4" exits.... don't want to use direct burial cable... am i missing something?? This must be done all the time

thx in advance, Pete

 

[Jim Port]

First thing is your can only have one circuit or feeder to an outbuilding. You will need a 4 wire feeder and to install a grounding system.

PVC boxes are drill on site.

 

[CodeMatters]

Please add your location to your profile. Very different rules in different
locations including US vs Canada.

 

[ptb]

Hi Jim. I am only running 1 circuit to the shed. The other 2 circuits are going elsewhere in the yard . The sub panel is being fed by 6/3 with ground, so not sure why 4 wire needs to be run to the shed. Not installing panel in shed. Project is in Idaho

 

[Oldmaster]

If you are installing feeders to a detached building 4 wires are required and grounding must be established at the building. 6/3 RX is not the correct conductor size for 100 amps.

 

[ptb]

I should clarify that the panel is equipped for 100 amps, 6 spaces, 12 circuits, but I am using only 3 20 amp circuits. My understanding is that 6/3 can carry that.

 

[Oldmaster]

What size overcurrent protection do you have on the 6/3?

 

[ptb]

Ok. Thought the circuit was grounded through the sub panel. Using a gfic breaker in the panel. Thought that as long as there was only 1 circuit to the shed a sub panel was not needed at the shed and a 10/2 or 12/2 with ground could power it up.

 

[Jim Port]

The 6/3 with ground is the 4 wires.

It sounded like the panel was going in the shed.

Why 6/3 for 3 20 amp circuits?

 

[Oldmaster]

So the sub-panel is in the house, correct? Sub- panel is fed with 6/3 RX. What size is the overcurrent protection for the sub-panel? From here you are trying to run a 1in. into the trench and distribute it into 3 conduits. No practical way to do this. You could run the 1 in. to the shed and divide it there. You don't need 1in. just 3/4 . No sub- panel needed in shed if only one circuit. Overcurrent protection for all circuits would be in sub-panel. Where in Idaho?

 

[surferdude2]

We did what you are proposing on almost every job. We used concrete pull vaults located in planter areas or other areas protected from auto traffic. It's common practice on commercial jobs that have several sign and lot light circuits. I suppose they may also make pvc or fiberglass ones but we never used any.

Concrete Pull Boxes

Non-Concrete Pull Box

 

[Jim Port]

If the 1" goes into a pull box it would be easy for 3 conduits to leave the pull box.

 

[ptb]

yea, Jim. the sub panel is at the house. The overload protection at the main panel is 40 amp breakers. Using 6/3 is overkill, but if I wanted to expand for future use like an outdoor kitchen ect didn't want to be limited. Thought about using a ground level pull box.... Canyon county idaho

 

[Oldmaster]

I lived in St. Marie's and Sandpoint. Was out there about a month ago. Hope to move back there some day. You can use a in ground box but they are pricey and when we used them in parking lots and airports the bosses were real fussy on how they were installed and arranged to drain. Don't think it would be worth it in your case but up to you.

 

[Oldmaster]

Looked at the smaller ones and they are actually rather cheap. Never used the smaller one.

 

[surferdude2]

I've done hundreds... maybe thousands of these... usually the concrete kind because it was plan spec. but I'd not hesitate to use a plastic one otherwise. We always used the vaults that had no floor in them since it made for easy install after the runs were cut to length and sometimes even pulled and made up. You'll notice the conduits don't come up and in with hard 90's... makes for easier pulls, especially important on long crooked runs.
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