Instal subpanel in second structure - Electrician Talk - Professional Electrical Contractors Forum

martinkulik · 05-07-2009, 09:34 AM

Hi,
I am running PVC conduit from Main panel in the house to a subpanel in separate structure about 25 feet away from the main house. The second structure will be used for office. Now I know I can't use more the 4x 90 angles of conduit, but general contractor requested to put the subpanel in area I would had to use 5 angles. I am wondering if I could use main circuit breaker disconnect on outside of the main house and then run raceway to the the subpanel, so I would eliminate use of 2 90 degree angles in a raceway.
I draw a picture so anyone could give me better idea how to do it.
Thank you.
Sincerely,
Martin

LawnGuyLandSparky · 05-07-2009, 09:44 AM

Turn your disco into a weatherproof pullbox. Turn the last 90 into a disco. That's only 2 90's in the pull.

Buck Parrish · 05-07-2009, 10:18 AM

Martin, Just use direct burial cable. No conduit required. Why break your back if you don't have to?

Jim Port · 05-07-2009, 02:36 PM

You could also use an LB at the new panel. The removable cover allows the access. Could you not come into the back of the first panel?

martinkulik · 05-07-2009, 03:00 PM

Thank you for your quick answers. So you can use weatherproof pull box in main feeder for the subpanel, because the line will continue without making a brake right?

martinkulik · 05-07-2009, 03:07 PM

Thank you again. You said I could use direct burial. I thought about it, but then partially it would have to be in the conduit where is going to against outside structure. I wanted to use #8 Stranded copper THHN because it would be easier to pull it through the conduit. Now if I change it to direct burial cable that size it would be really hard to pull it through the conduit even though it will be probably only 10 feet.

erics37 · 05-08-2009, 03:05 AM

Quote:

Originally Posted by martinkulik

Thank you again. You said I could use direct burial. I thought about it, but then partially it would have to be in the conduit where is going to against outside structure. I wanted to use #8 Stranded copper THHN because it would be easier to pull it through the conduit. Now if I change it to direct burial cable that size it would be really hard to pull it through the conduit even though it will be probably only 10 feet.

Direct burial wouldn't need a conduit if put in a trench the proper depth and sleeved for protection where it comes out of the ground. It would be more prone to damage and would be much more difficult to replace for future expansion, so I would say conduit and individual conductors is the way to go.

From your picture, you could do away with the disconnect on the main building and use an LB to get out of the wall. It would also allow your conduit to sit closer to the wall for support straps without having a weird gooseneck thing going on. Same deal at the subpanel end. It would make it easier to penetrate the wall to the interior, and it would eliminate some 90s.

NevadaBoy · 05-08-2009, 09:16 AM

Quote:

Originally Posted by erics37

Direct burial wouldn't need a conduit if put in a trench the proper depth and sleeved for protection where it comes out of the ground. It would be more prone to damage and would be much more difficult to replace for future expansion, so I would say conduit and individual conductors is the way to go.

From your picture, you could do away with the disconnect on the main building and use an LB to get out of the wall. It would also allow your conduit to sit closer to the wall for support straps without having a weird gooseneck thing going on. Same deal at the subpanel end. It would make it easier to penetrate the wall to the interior, and it would eliminate some 90s.

Yep, I would use LBs on both structures. Then you could put the new panel inside anywhere you wanted.

running dummy · 06-05-2009, 06:31 PM

yea definitely LB's. make sure you pound a ground rod too if they adopted the 08 code

**Speedy Petey** · 06-05-2009, 11:14 PM

Quote:

Originally Posted by running dummy

make sure you pound a ground rod too if they adopted the 08 code

What does it have to do with '08? A ground rod was always required at a detached structure with a feeder.

mcclary's electrical · 06-18-2009, 10:27 AM

not if less than two circuits

**Speedy Petey** · 06-18-2009, 12:57 PM

Quote:

Originally Posted by mcclary's electrical

not if less than two circuits

That is why I mentioned a feeder, as opposed to a MWBC.

220/221 · 06-18-2009, 02:27 PM

Quote:

Martin, Just use direct burial cable. No conduit required. Why break your back if you don't have to?

Worst.....advice.....ever.

Wiring needs protection and sometimes it needs to be replaced.

And....break your back? You still have to dig. How hard is it to pull wire in properly installed conduit.

It's no more difficult to install conduit and wire.

lectricboy · 06-18-2009, 03:16 PM

Quote:

Originally Posted by Buck Parrish

Martin, Just use direct burial cable. No conduit required. Why break your back if you don't have to?

I know direct burial cable is approved for it's use. But in my opinion whenever you bury cable in the ground, you are asking for trouble. I have seen direct buried cable fail too many times (everything from rocks to moles to tree roots). I would stay with the conduit, you can always repull if something goes wrong.