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+-- Thread: Sub Panel QUestion? (/showthread.php?tid=7163736)
Sub Panel QUestion? - PedroOhare - 12-09-2015
I am thinking about running a 60 amp subpanel to my garage. Would this work?
https://madison.craigslist.org/mat/5315236554.html
It would go about 40 feet in my house running through the basement ceiling (1st floor floor) joists, then down and about 10 feet underground outdoors to the garage, then up and into the garage. I would expect I have to run a separate ground wire to a ground rod from the subpanel? I understand I need to place the wire in conduit where it exits the house and enters the ground to a depth of 18 inches (and vice versus where it exits the ground and enters the garage. If I bury the wire 24 inches I do not need to use conduit in the horizontal area underground? If I bury the wire 18 inches I can run it in PVC conduit? It is kind of a hard to access area to dig so if I use rigid metal conduit, how deep do I have to go (and am I limited to 20 amps/120 v?)? This seems like a good price on the wire and would be worth it to get if it would work.
My plan is to get the approval at the city, but I don't want to look like an person when I go in there, dig the trench and string the wire and then hire a licensed electrician to make all the hook ups. Between the city and the electrician inspections I would feel pretty confident but I would like to do as much as I can for cost savings (and did I mention I don't want to appear an person?).
Thanks
Pedro
Re: Sub Panel QUestion? - TDKPE - 12-09-2015
You need both a grounding electrode system (2 ground rods typically), PLUS an equipment grounding conductor run back to the main panel. 3-conductor feeders to outbuildings are no longer allowed, unless your town is on a pretty old Code cycle.
I also couldn't see the insulation code, but it may not be legal inside your dwelling unit.
Re: Sub Panel QUestion? - PedroOhare - 12-09-2015
Would this be what I need then?
http://www.homedepot.com/p/Southwire-2-2-2-4-Aluminum-SER-Wire-By-the-Foot-13102999/205001908
Pedro
Re: Sub Panel QUestion? - crokett™ - 12-09-2015
2-2-2-4 aluminum is plenty for 60A, and yes that's what you need. Here it would be good for up to 90A. Make sure you get stranded and not solid if you can find it. You are also correct that 18" in conduit is minimum, 24" not in conduit. Copper you could go with a smaller conductor that would be easier to work with but it would be more expensive.
In your sub panel you need to be able to remove the bond between the ground and neutral buses. If the panel doesn't already have a separate ground bus, you can add one.
Make your conduit oversized, it makes pulling the cable much easier.
Re: Sub Panel QUestion? - Charlie - 12-09-2015
Read the link. Not approved for underground use. Even in PVC conduit. The NEC considers underground conduit a wet area. The cable shown 2-2-2-4 has a bare aluminum ground and bare aluminum can not be buried. It will turn into a white milky paste from ground water.
Re: Sub Panel QUestion? - crokett™ - 12-09-2015
you are correct. this is what he wants
http://www.homedepot.com/p/Southwire-2-2-2-4-Aluminum-Quad-Dyke-Wire-By-the-Foot-55417399/205001803
I buried 2-2-2-4 aluminum as a feed to my shop, so I know you can get it burial-rated. Around here it is also known as mobile home feeder.
Re: Sub Panel QUestion? - Charlie - 12-09-2015
URD cable is not permitted to be used in a dwelling. As Tom said in his post make sure the insulation on the cable is permitted for use inside a dwelling. The original post says it will run 40 feet inside the house.
Re: Sub Panel QUestion? - Mandrake - 12-15-2015
If cable like this is not good for runs, even short ones, inside a building, than what good use does it have? Or what do you do when you transition through the wall and have 20" to go to get inisde a panel?
I have been thinking of Service Entrance Cable for a feeder to a new subpanel in my workshop. It too would travel 20" through a wall, then into the UG conduit for 20', then another 20" in a wall to the new box.
Re: Sub Panel QUestion? - Charlie - 12-15-2015
One method would be type UF cable, it is listed for direct burial and can be attached to your joists in the basement. Another method would be conduit and wire with insulation approved for use in a dwelling. Types THWN, XHHW, RHW are approved for this. Service entrance cable can not be used underground. Types URD and USE can not be used in a dwelling, they are used for underground applications where you would run from the utility to your meter on the outside of the structure.
Re: Sub Panel QUestion? - TDKPE - 12-15-2015
What Charlie succinctly stated above. I would only add that THHN is often dual-rated THWN, so if you're considering separate conductors in conduit, look at the insulation type on the actual stuff you're buying rather than just a web site description, like on a BORG's web site, which may not accurately reflect dual-rated insulation.