Al 4/0 wire to pole building

[xkvator]

i'm going to run power to a Morton building from a garage subpanel...years ago, I ran #1 copper(4 wires) from the house out to the detached garage...now I want to run AL to the pole building from the garage panel...about 100'. I already have 3" conduit ran...

My 1st question is: I see there is 4/0-4/0-4/0-2/0 and 4/0-4/0-2/0-4 wire...

can I use the smaller neutral/ground...?

 

[yatg]

4/0 AL is big wire, too big for your current situation.

You're going to be limited by how much capacity you have at the garage. What's the garage feed breaker size at the house and the disconnect breaker size at the garage? In most cases, the lowest value is the max you'll be able to feed to the new building. Size the wire from that for starters, bump up for voltage drop.

Don't undersize the neutral, not worth the headache.

The EGC size can be smaller based on the selected wire size.

On the bright side, that 3" conduit is going to be easy to pull though.

 

[mike93lx]

Why do you think you need 4/0 AL?

 

[wyliesdiesels]

Lets back up.

What size service do you want?

What loads do you have?

 

[theoldwizard1]

Answer these first

Lets back up.

What size service do you want?

What loads do you have?

...can I use the smaller neutral/ground...?

The short answer is yes. Very common for ground to be smaller. I don't know how it is sized. Neutral can be smaller also, but how small depends on the total of 240V load vs the total of 120V loads.

 

[sberry]

One is for service entrance and the other for use where voltage drop is a concern for long runs.