Electrical service length

Question

How can I run an electrical service 1000 feet to my cabin? I only need 100 amps. It seems like no matter what size wire I use, the voltage drop is very high. Any suggestions on wire size and how to best do this?

Answer 1

My neighbor buried 1500' of 2" pvc for the utility to pull primary 7.2kv to a pad mount transformer 25" from the house. He had to buy and bury the conduit and the vault pad. Utility supplied wire and transformer.

The utility first asked for 2.5", which he successfully argued down to 2" which was half the price of 2.5". The primary wire is small, carries under 7 amps @ 7.2kv to supply 200A at 240v. At 7.2kv there is effectively no voltage drop.

Answer 2

It seems like no matter what size wire I use the voltage drop is very high.

That's not how voltage drop calculations work. You don't pick the next larger size then do the calculation, get a bad number and do it again. You provide the calculator your data e.g. 1000', 80A worst case normal load and 5% voltage drop tolerable, and it spits out what size of wire you need. Vitally, you switch the calculator to aluminum wire, because running copper this large isn't even stupid.

Also, the US is a 240V country, so be entering 240V not 110V.

In that example I got 400 kcmil at 4.70%, or 500 kcmil at 4.01%.

Since you are talking about $7000 in wire alone, and probably that again for trenching, I would evaluate off-grid solar/battery.