I am installing a 60 amp subpanel in a workshop in my backyard and I will have 2 - 20 amp services with 4-5 outlets on each and 1 - 15 amp service for lighting. The length from the main panel to the workshop is about 105 feet. I will be using a double pole 60 and GFI circuit breaker in the main panel to a 60 amp pull out on outside of work shop then inside to the subpanel. What would be a good size wire. I may run one saw at a time or a couple of saws.
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This answer might be helpful.– Tester101Mar 29, 2015 at 1:52
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2 Answers
6AWG copper wire would be the minimum for a 60A subpanel but with a 105ft distance you have too much voltage drop and need to go up to 4AWG copper to keep the voltage drop within acceptable limits (usually 5%).
answered Mar 28, 2015 at 23:30
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As soon as you come to from pricing 4ga copper, 2-2-2-4 Al URD or SEU will seem like a bargain. On a final note, you are going to use conduit, right? As a bonus, when you use direct bury in conduit, it is 'protective' and not subject to strict conduit rules.– Some GuyMar 29, 2015 at 2:00
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@SomeGuy "When you use direct bury in conduit, it is 'protective' and not subject to strict conduit rules.". Can you cite a code section for that? Mar 29, 2015 at 2:26
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I am running in 1 1/4 inch conduit underground and each end has about 4 ft of 1 inch conduit. I was originally going to do 4-4-4-6 Mar 29, 2015 at 6:01
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@Tester101 - Realizing that the NEC is restrictive and not permissive. Under the chart in 300.5, column 1, under buildings is the only place that most (but not all) direct burial cables require a raceway.– Some GuyMar 29, 2015 at 20:20
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#4 copper would limit the voltage drop to 1.51%. #3 aluminum would limit the drop to 1.95% both calculations 105 feet at 60 amps.– Ed BealJan 4, 2018 at 19:29
The National Electrical Code Book / Article 110.14 (c)(1) identifies temperature limitations for circuits and feeders of 100 amp or less. If the circuit is 100 amp or less you have to size the conductors based on the 60-degree celsius column unless the breaker and the equipment terminations are rated for 75 or 90 degrees.
You have to use a #4 conductor to feed a 60 amp circuit.
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1Just about all breakers and loadcenters in use are marked and rated for 75degC terminations... Jul 6, 2018 at 22:14