Help on subpanel

[nate379]

I am putting up a shed in the back corner of my place this summer and plan on running power out to it. I'm going to run a 30amp 240v feed to run an air compressor and a few lights/outlets.

From the garage I plan on digging a trench to the shed.

Now... what should I be using to go through the garage wall into the ground, come out at the shed and panel in the shed.

Would that panel need to be grounded on it's own, or will the garage ground be ok?

I'd have an electrician help me but they are fawking expensive and the last 2 that were at the house were incompetant... as in... I had to go in and later fix there work.

 

[nadogail]

******, with a plastic bushing, out of the panel into an LB. Run conduit down the wall with a minimum of 4 10 Guage conductors, 2 hot, neutral, and a ground. Trench to the shed, conduit up the wall to another LB, then ****** into your Sub Panel (Plastic Bushing in the Sub Panel). Ground and Neutral are to be seperated.

Ask your inspector for details on your local requirements.

 

[shamrock12]

Yup, use the conduits as a sleeve on the wall. I'd also put male connector with plastic bushing on other end of conduits in the ground too. You should be able to use 10/4 UF direct buried in the ground, unless the distance is long (like over 100') or you'd have to upsize the conductors.

Unfortunately, because this would be 240V/30A subfeed, it would have to be buried much deeper than a standard 120V/20A circuit. According to NEC Table 300.5 it show that for direct burial, it'd have to be done at minimum depth of 24". However you could bury at minimum depth of 18" if you use PVC conduits for the entire run. As for a separate grounding at the shed, it generally would not be required but local codes may vary so be sure to check it out.

 

[sberry]

I like the number 2 alum for this kind of install, 90A wire for the same cost as 30A copper wire.

 

[shamrock12]

I should also note that if you are going to use conduits for the entire run, you cannot run romex or UF cable in there. It would need to be individual conductors without sheathing.

 

[Charles (in GA)]

I should also note that if you are going to use conduits for the entire run, you cannot run romex or UF cable in there. It would need to be individual conductors without sheathing.

Not true. You do still have conduit fill requirements to adhere to (see Chapter 9 Tables, note (9) in the back of the NEC), but there is nothing to prohibit use of romex or UF in conduit (other than it is dang difficult to pull).

Charles

 

[shamrock12]

Not true. You do still have conduit fill requirements to adhere to (see Chapter 9 Tables, note (9) in the back of the NEC), but there is nothing to prohibit use of romex or UF in conduit (other than it is dang difficult to pull).

Charles

Better check again. NEC article 378.10(1) - only for exposed work.

 

[walrus]

Better check again. NEC article 378.10(1) - only for exposed work.

378.10(1) refers to non metallic wireways???
Edit:http://www.carlon.com/Master Catalog/Wire_Safe_Wireway_and_Wiring_Trough_Brochure.pdf

 

[Charles (in GA)]

Better check again. NEC article 378.10(1) - only for exposed work.

Try again, this reference has nothing to do with sheathed cables and conduit.

Charles

 

[roger55]

Try again, this reference has nothing to do with sheathed cables and conduit.

Charles

Isn't it true that it is OK to use Romex inside conduit as long as it's not underground?

If it's underground, then you have to use THHN in the conduit, right?

 

[shamrock12]

Try again, this reference has nothing to do with sheathed cables and conduit.

Charles

Correct, I overlooked the "nonmetallic wireways" article instead of "nonmetallic sheathed cable".

You still cannot use Romex for underground installation, even inside a conduit system. Article 300.5(5) & 334.10(A)(1) prohibits it. You still could run UF in a conduit but that defeat the purpose of using expensive UF instead of THHN or other listed for wet location/direct burial. Not to mention that it is even more difficult to pull than Romex. So it is impractical, and near impossible to do, therefore that's why I said it cannot be done.

This is not a code forum so I was only trying to keep things simple and not to cause confusion by giving out too much details that only have little or no point to the issue. This thread is about running a subfeed to a shed, not indoor wiring. Keep It Simple Stupid.

 

[Charles (in GA)]

Indeed, Romex is not suitable for wet locations, and the inside of a nice dry, well glued together conduit, buried underground, is a wet location.

I try to stay away from "flat a$$" statements since they confuse someone. In this case, by the time I got down to your post, I had forgot that he was running conduit underground, all I was looking at was "sheathed cable + conduit = bad" which I knew was not so.

Personally, I'd drop the conduit into the ground two foot with a 90° bend to horizontal and stop, and run UF buried directly, thats what its intended for.

Charles

 

[nate379]

I was thinking of running 2" flex black PVC (comes on a roll used for water) and running an air line and the wire inside of that.

Wire is going to be in the $2-3/ft range one way or the other. I could use Romex and I bet it'd be fine, but might as well do it "right".

THHN is single conductor right, where I'd have to run 3 wires?

As far as subpanel wiring...

If I ran 2 hots and the neutral off my main box into a subpanel, then added a ground rod at the shed would that be legit? This is the way my Dad wired his shop about 20 years ago.

I have a decent understanding of wiring concepts, but I'm not up to date on code. I have a good idea on what is "common sense" safe or not, but would rather do it to code if practical.

 

[Joe92GT]

You need to run 4 wires, and have a ground all the way back to the main service entrance. The ground wire can be sized smaller.

Also, running the air line in the same conduit as the wire will not meet code.

Save your self a huge headache, and do not use flexible conduit. It is extremely hard to pull wires through.

 

[nate379]

I was just going to stick a fishtape through the poly pipe and pull everything through.

http://www.sprinkler.com/buy/item/poly_pipe/19913

I could just run the poly pipe for the air line protector and use UF burial wire in the trench though.

I'm planning on just running 30 amp service out to the shed. Couple lights/outlets and the compressor. Compressor pulls 15 or 20 amps I believe.

 

[nate379]

If I run a conduit for the air hose can I zip tie the UF wire to that conduit?