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Handyman2007 12-29-2007 02:00 AM

Multiple Sub Panel Installation
 
I have a question regarding the use of multiple sub panels. We have a detached garage without electricity and I installed two sub panels this weekend and installed a few outlets (all GFI protected) and regular light bulb outlets in garage. The reason for two sub panels: The main box inside the house is a 100 amp box with all of the circuits used, so in order to make room for a 40 amp double pole breaker for a sub panel, I installed a sub panel next to the main panel and moved two 120v circuits to the sub panel (used #8 wire as the feed). This provided the room I needed for the sub panel breaker in the main box. I then ran 100 feet of #8 wire out of the house into PVC pipe to the garage. I attached the #8 cable into the sub panel in the house on the same lugs as the feeder #8 cable from the Main panel. I used 4 breakers in the garage (very much overkill for circuits that won't get used hardly ever. My question is: Is it OK to have connected the garage feeder wire to the sub panel next to the main panel? I know I probably should have changed out the main panel to a larger service, but that would have required removing the meter etc. and I didn't want to do that.

If anyone thinks I did something wrong, please let me know.

Drennen 12-29-2007 02:35 AM

No problem that i see as long as you got your sub panel on a breaker it don't matter witch panel your circuits are on as long as you don't over load either of your panels. all so unless you have all gas appliance or a small trailer i would make upgrading your panel your next home improvement. 100 amp is pretty small for as much stuff we run now days.

Handyman2007 12-29-2007 09:40 AM

Thanks. I thought it would be ok. One other thing. I ran the #8 cable in grey PVC to the garage. Does the #8 cable have to be weatherproof cable since it is enclosed in the PVC? I bought a roll of #8/3 wire but I don't think it was rated for direct burial. I assumed that since it would be going thru the PVC pipe, that it would be well protected from the elements.

Drennen 12-29-2007 11:31 AM

Quote:

Originally Posted by Handyman2007 (Post 83630)
Does the #8 cable have to be weatherproof

No. As long as you glued your pvc and its water tight.

Handyman2007 12-29-2007 12:04 PM

Thanks for the reply. I did glue the pvc together.

Andy in ATL 12-29-2007 01:51 PM

Quote:

Originally Posted by Drennen (Post 83656)
No. As long as you glued your pvc and its water tight.

That is WRONG. Romex cannot be installed in pvc outside. Just because the pvc is glued and "watertite" doesn't mean a thing. I know that sucks, but it is the code.

Mike13 12-29-2007 02:21 PM

I agree w/ Andy. The PVC is still considered a "wet" area by the NEC & thus NM cable can not be run there.

There are still many other items you need to be sure were done correctly i.e. did you keep the neutral & ground wires isolated, what is the temperature rating of the cable/wire (can't use the ROMEX anyway), how deep is the trench, did you use ground rods & how were they installed, etc?

Handyman2007 12-29-2007 05:06 PM

Ok, thanks for the additional information. I read about the grounding rods on another post.

HouseHelper 12-29-2007 06:50 PM

Quote:

I attached the #8 cable into the sub panel in the house on the same lugs as the feeder #8 cable from the Main panel.
If you have two wires under the same lugs, that is a violation and should be corrected. The feed to the garage panel should come from a breaker in the house subpanel.

pb slinger 12-30-2007 02:07 AM

hi all.........I've seen the comments about electrical cable run thru glued pvc on here before, and was hoping someone could explain the reason a little more in depth.........not arguing the code, just would really appreciate more info, cuz' like many others it seems to me that in a sealed dry plastic conduit is not out in the wet location, be it in a crawl space, attic, garage, or shallow trench.........??

LawnGuyLandSparky 12-30-2007 03:34 AM

Quote:

Originally Posted by pb slinger (Post 83833)
hi all.........I've seen the comments about electrical cable run thru glued pvc on here before, and was hoping someone could explain the reason a little more in depth.........not arguing the code, just would really appreciate more info, cuz' like many others it seems to me that in a sealed dry plastic conduit is not out in the wet location, be it in a crawl space, attic, garage, or shallow trench.........??

Wire insulation and cables are rated for location among other things. Inside a conduit - be it running through an attic or underground to a garage is NOT a location. Underground is underground. Outside in the weather strapped to the side of a building is outdoors. Running through a basement is indoors - running through an unheated damp carwl space is a moist location.

If you think the interior of a conduit buried underground constitutes "indoors" you would be wrong. It WILL get wet inside that pipe. It's not hermetically sealed. It's not protected against the enviroment that envelpes it.

Andy in ATL 12-30-2007 06:38 AM

Condensation forms over time and the pipe WILL fill with water.

pb slinger 12-30-2007 10:09 AM

.........OK that makes sense then.......particularly about the condensation forming inside the conduit, I appreciate your time & patience in explaining that, rather than just the typical " don't do that, its stupid and wrong and you will die" response some like to give. What exactly does the moisture do to the wires anyway that the insulation does not protect them from.....or is it just the fact that IF there were a break in the insulation it would cause a short circuit?.....
........trying to learn here & you guys seem to be very knowledgable and willing to share information.........local electricians won's answer questions for homeowners much.just want their $$$$ to come & offer an estimate to do the work themselves......so this is really appreciated..........you guys help us DIYers out, and keep us safe..........knowing we're probably going to try to tackle the job anyway, so we might as well be educated as much as possible about it...........
If ever through the Atlanta area for business, I'll take you & your family out to dinner Andy!

Andy in ATL 12-30-2007 10:34 AM

PB,

My opinion and my opinion only... The romex is not listed or allowed in the conduit. The code is clear on that. The type wire typically used in PVC is THHN/THWN. Go to your home center and take a piece of #12 THHN/THWN and a piece of #12 romex and compare them.:whistling2: Not much difference, but that doesn't change the fact that it is against the rules. Thanks for the dinner offer, Andy likes food.:laughing:

tribe_fan 12-30-2007 12:33 PM

Andy - can "outdoor' romex ( sorry I forget the correct term, but the kind rated for direct burial) be placed inside PVC for added protection in an outdoor environment ?

I'm referring specifically to 12 and 10, I've never seen it in higher sizes.

I looked at other web sites, and this topic get a lot of discussion.

Thanks !


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