60 amp service in detached garage 200' of service wire

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Old 09-19-11, 07:18 PM
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60 amp service in detached garage 200' of service wire

I have a detached garage that I would like to run electric too from my house. My house has 200 amp panel. I'll just use the service to the garage for lights, a refrigerator, television, basic tools, some outside lights, etc. Will 60amp be sufficient or should I run larger? I'm told the 200 total run of the wire may be an issue and I should just run 60amp. Would you recommend I use aluminum or copper wire? What size wire should I use for each?
 
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Old 09-19-11, 07:42 PM
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As long as you're not using a welder 60A is plenty. For 200'@240V you would need #4 copper or #3 aluminum with 3% Voltage drop
 
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Old 09-19-11, 07:54 PM
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Unless your going to go big and start using some high draw items like a large welder, larger compressor, or electric heat, 60 amps will do you plenty fine.

The only issue is voltage drop. To do a drop calculation you need to know your expected load. The load will not be 60 amps since this is you max you are looking at but a quick and dirty calculation on the net gives you 3.2% drop with #2 aluminum at 60 amps load. A 2-2-2-4 aluminum quadplex will be easily available from the big box stores as it is used a lot in services.

I would install a 100 amp, 20 circuit+ main breaker panel (value pack) in the garage. Direct burial 2-2-2-4 aluminum Quadplex, and install a 60 amp breaker in the main panel.

BTW - Welcome to the forums!
 
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Old 09-19-11, 08:31 PM
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Thank you for the information it is greatly appreciated! I was thinking of putting the wire in conduit in the ground, do you have a recommendation on what size conduit to use and how deep to bury it?
 
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Old 09-20-11, 10:18 AM
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Use PVC conduit, buried 18" to the top of the pipe, and go no smaller than 1-1/4". For that distance I would lean more toward 1-1/2" to allow for an easier pull and room for future growth if needed. The price difference is minimal.

If you think you'll want phone, tv, data, security system, out there at some point, go ahead and bury a second 3/4" PVC conduit in the same trench at about 12" deep. You can just leave the ends capped if you don't have a use for it now, but it will be really handy if you ever need it.
 
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Old 09-20-11, 11:13 AM
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Great information! Thank you! Today I've recalculated the footage of wire needed to have a more direct feed to the garage (was trying to avoid going across the irrigation), but on the recalculation, the maximum wire run would be 150'. Should I stay with the 2-2-2-4 aluminum? Also, a friend of mine works at an electrical supply and suggested since my home panel is in front of house and I want to run out the back of house, that I run the 2-2-2-4 "wrapped/protected" (for lack of better words) cable though the basement trusses through the subfloor header board into a junction box (put on back of house) then run the 2-2-2-4 wires (the 4 separate wires he can provide me that are not in a cable) from the transition/junction box into conduit up to the detached garage. Is this okay?
 
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Old 09-20-11, 12:14 PM
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that I run the 2-2-2-4 "wrapped/protected" (for lack of better words) cable though the basement
Specific type of cable please? Some types such as mobile home cable are not approved for inside use.
 
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Old 09-20-11, 12:27 PM
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It's called house cable "walser2cut" with a description of SER-2-2-4-AL. Also, the wire he is saying that would go in the conduit is a 3 wire and an extra wire (is what he has readily available) and is described as: conduit cable: WALSTEPHENSCUT with desc "WIR2-2&4-1-AL-URD-STEPHENS CUT, and then WALXHHW2BKCUT with desc "WIRE XHHW-2-BLK-STR-AL". Thank you!
 
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Old 09-20-11, 01:11 PM
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60A with #2 aluminum is really a lot of power for the usage you're describing. Unless you're getting a really good deal on the aluminum it's overkill for what you need. The cable your friend is offering isn't exactly right anyway, so it's kind of a hodge-podge of materials that you don't really need.

I'd put the conduit in and pull through a 20A multiwire circuit using #10 copper THWN wire in black, black, white and green from a 20A double-pole breaker in the main panel. You don't need a subpanel or ground rods in the garage for this type of install. The white neutral is shared between the two hots and it is effectively two 20A circuits. All you need at the garage is a disconnect switch and two GFCI receptacles in the first box. After that you can wire two circuits through the garage using 12/2 romex to lights and receptacles.

See what your friend can do on 300' of black, 150' of white and 150' of bare or green #10 copper. At a supply house he might even have cutoffs or roll ends long enough to meet your need. Make sure the 150' measurement is right too, and add some for good measure.

In the future if you need more power in the garage you can pull the #10s out, sell the scrap, and replace them with larger wires and put in a panel at the garage and the whole 9 yards.
 
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Old 09-20-11, 08:14 PM
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While all the info your are getting is all great, the only reason I suggest #2 aluminum and 60 amp is for the future. Depending on your budget and plans for the garage, doing the 1 1/2" PVC (and 1" for low voltage) and pulling in #10 copper and using a 30 amp, two pole breaker is a decent option. I would tend to still go with a 20 circuit 100 amp value pack panel because they are only about $50
 
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