What Size Wire For 100 Amp Service 400 Ft Away

have you considered a transformer at each end?

i would call whoever the local POCO uses for putting in poles and see what they would charge to run the poles and wire. I have heard they can sometimes do the poles for $500 or less each. if he insists on UG, this is not an option, but a 600 ft trench is going to be pricey.

is there a utility line near the outbuilding already? if not, you may be out of luck there.

in any case, it will not be cheap.

Last edited: Aug 20, 2012

An electrical contractor that I know & respect did a cost comparison on wiring a golf course that required electrical at each station. He used step up & step down transformers and was able to do it entire job in # 10UF. Saving a bunch. So as mentioned above, it would be worth a comparison.:slaphead:

I quoted something similar for a golf course, two fans at about every other hole, around 1200' on average. They didn't like my price. Someone else ended up doing it and I would say with a much smaller wire from the price I heard it went for. I didn't see any transformers at the holes either, so they must have used the existing 208 volts for the 240 volt fans. Glad we didn't get it anyway, they had no idea where all of the irrigation lines, controls, and private utilities were located.

ActionDave

I'm looking for a few ideas for a friend who wants to set a 100 amp sub-panel, 600 ft from his
200 amp main panel at his house. He wants to do it underground. I did a quick voltage drop Calcand came up (4) conductor, 400 kcmil alum. URD.

I'm thinking their must be a better way, plus you wouldn't be able to terminate the 400 kcmil al on a 100 amp breaker. So I'm thinking his best bet is to get the utility company to do a drop at
the out-building.

Any ideas?

Actual load or load calcs are needed, otherwise voltage drop calculations are useless.

Because it's my business to throw this out there...

Has he considered an off-grid solar system?

iceworm

Curmudgeon still using printed IEEE Color Books

... Has he considered an off-grid solar system?

Just curious. What is the going rate on 24KW Solar installs? $10/W?

ice

iceworm

Curmudgeon still using printed IEEE Color Books

I'm looking for a few ideas for a friend who wants to set a 100 amp sub-panel, 600 ft from his 200 amp main panel at his house. He wants to do it underground. ... Any ideas?

Well, as mentioned, fat wire, or a pair of 240/600V, 25kva xfm are the best options. There are some if he doesn't have to have 24kw. What is the planned load?

ice

Just curious. What is the going rate on 24KW Solar installs? $10/W?

ice

First of all, the size of the system depends on overall usage, and you can't assume what that is based on the 100A figure mentioned. Most likely he won't need anywhere near a 24kW system.

As for the going rate, for off-grid at 24kW, probably about 7$/W, but it's fairly useless to quote an industry average figure without knowing the specifics of the job.

iceworm

Curmudgeon still using printed IEEE Color Books

.... Most likely he won't need anywhere near a 24kW system.

... probably about 7$/W ....

...Complete with battery bank?

I just wanted to make sure i had the numbers in perspective. For similar costs as a 24KW install, 600 feet of fat wire (or skinny wire and xfms), ditch, replacing the grass, feeders, disconnects, and panels, the customer can get about 2.4KW on Solar.

ice