Need some assistance in determining the size and type cable to use for burial feed to my garage. Garage isn’t built yet, I want to dig the trench and install cable this year, complete the garage next summer. Nothing special in the garage, just lights and a few outlets, maybe one 220 recep.
Thanks. Andy
Replies
Andyb,
I would suggest, at least a 100A panel. Which would require #2 4-wire urd (aluminum). And in PVC conduit. You may want to think about a second smaller conduit also, just in case you decide to put in a telephone, cable TV etc.
Northeastvt
Before this can be answered, you need to find out how far it is (along the burial route) from the main panel to the proposed sub panel. This will impact your sizing.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
If your hair looks funny, it's because God likes to scratch his nuts. You nut, you.
Approx 110' from main panel to sub panel location.
Thank's Paul, I should have asked that. Thought of it after I hit the post button. I don't think voltage drop should be a problem at that distance, but maybe somebody else will chime in who know's for sure.
northeastvt
#2 aluminum is rated only at 90a (NEC Table 310-16, 75-degree column). It's use as 100a service entrance wire is an exception, not the rule. So for 100a you'd need #1 aluminum or #3 copper.
Ed
Edited 11/1/2007 5:12 pm ET by edlee
I would suggest that you do not install the cable at this point in time.
If you want to trench now (perhaps have an excavator on site for some other purpose?), go ahead and trench but install only PVC conduit at this time.
Prep and glue the joints well and cap at both ends to keep the critters out.
2" would handle 100A service to garage? Ask at supply house - conduit's cheap, go bigger if in any doubt.
A second, smaller, run in the same trench is also good idea for telephone, etc.
The actual wires will do nothing but deteriorate over the winter -- if it does not get stolen!
Jim
Never underestimate the value of a sharp pencil or good light.
Andyb - not an expert or professional, but here's my 2 cents.....it's mainly some questions that I think need asking based on my experience wiring up my shop(where's Bill Hartmann on this one?):
1) Are you running your line to the subpanel by tying it to a circuit breaker on the main service panel? Unless I missed something, the answer to this will make a big difference on what you need to do.
2) "just lights and a few outlets, maybe one 220 recep" doesn't require the overkill and extra cost of 3 gauge copper line for 100amp capacity. For example, I'm using 6 gauge copper from a 60 amp breaker on my main service panel to run electricity out to a wood shop. 60 amps is more than enough capacity for my one-man shop, even with a tablesaw, bandsaw, heater, lights etc in there.
3) Is your garage going to be attached or detached? I'd assume detached, right?
That's it from me. Could be you guys are all on the same wavelength, you're not doing a breaker off the main, and what I'm asking doesn't matter. But hey, what's 2 cents if you can't spend it? Meanwhile, I wouldn't be surprised if Bill pops in here at some point.
charlie -- "Count your blessings....it could always be worse!"
Edited 11/1/2007 9:45 pm by charlie4444
At very close to the same distance (from our garage subpanel) we built a 400 SF outbuilding with the following:
5-6 interior light fixtures + 1 exterior fixture
1 400W plant light
220V / 2200 W in-wall electric heater
maybe 10 receptacles
We ran 3 #6 copper plus ground in 1 1/2" PVC (IIRC) with an intermediate PVC pull box and drove 2 or 3 copper ground rods out near the outbuilding. 60 A main breaker.
No problems - we also just replaced the exterior fixture light switch with a Lutron RadioRa switch with a repeater in the garage. Thus, without a separate switch leg to the shed, we can switch the exterior light on/off from the house over 125' away.
If I did it again I would run 2" PVC as noted.
HTH - Jeff
Edited 11/1/2007 9:52 pm ET by Jeff_Clarke
jeff,
With the cost of copper now, I bet 100A with #2 4wire (it is a sub panel, so the four wire is needed ) would be more cost effective. Even the panel would not be much more. And in this area #2 is used for 100amp, 4/0 for 200amp, unless it is an extremely long run. 10/3 is well over a buck a foot, 2-4 is not much more. Not all of this post was aimed at you just the copper vs aluminum part.:)
Dennis
Yep. Ours was run in 2002. All our (more recent) interior 100A feeder cable is 2/0 Alumaflex XHHW.
Jeff