What size of copper wire and conduit should I use for a 150' run to a sub panel?

What amperage sub panel do you need?

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Originally Posted by nbsproducts

What size of copper wire and conduit should I use for a 150' run to a sub panel?

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100 amp

Quote:

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Originally Posted by nbsproducts

What size of copper wire and conduit should I use for a 150' run to a sub panel?

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Maybe a little more info would help. I have a 200 amp main service and am building a new shop located 150' away. Code says I can bury @ 18" conduit and power to a sub panel. I was going to do a 70 amp service using 2" conduit and #4 copper, but folks have convinced me to go to 100 amp. I'm not sure about the increase in wire size an conduit size required.

Thanks,
Joe

More detail is always better, allows for a better detailed answer.

While #4 copper is allowed for a residential 100 amp feeder, if the feeder is loaded to it's max of 80%, it will produce a voltage drop of 7.4 volts. The recommended max is 3%, 3% of 240 volts is 7.2, so #4 is borderline. If any motors will be used the Vd will be higher during starting, so probably should use #2 copper to have a cushion.

To save money, you may want to compare the price of aluminum #4/0 4 wire URD cable. #4/0 is normally used for 200 amp feeders. Check to be sure Al is allowed in your area.

For a feeder of 150 foot with either #4 or #2, I would use 2 " PVC to allow the wire pull to be easier. if you decide to use #4/0, I would use 2.5 or 3".

Be sure to pull 4 wires, 2 live, 1 neutral, and 1 equipment ground, which can be no smaller than #8 copper, but I would use #4 copper for this distance. Also, be sure to keep the neutral isolated from the equipment ground at the subpanel by using a separate ground bar for the equipment ground, and do not connect the neutral to the ground at the panel. Will also need at least one ground rod at the subpanel. Ground any interior water lines to the ground.

Quote:

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Originally Posted by nbsproducts

What size of copper wire and conduit should I use for a 150' run to a sub panel?

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Thanks tkrussel

The contractor is preparing to pour the footings, so I'm adding the ground rod at the shop. I'm not sure here in the PG&E area if they want me to gound the carried gound or not, but it sure makes since to me. I need to ask but they are closed today. Thanks again, you have been very helpful.
Joe

Hey, don't forget to throw in 2- 3/4" PVC for TV and Telephone. You will thank yourself later. Doesn't get easier or cheaper than now.
May want wires between for 3 way switching of lights.

I already have extra pvc runs, just got to get them in the foundation. TenBaseT for internet also.

Thanks Guys

Avoid wireless when you can, good thought.
Maybe stub out of slab conduits for landscape lighting, Electric gate?