Ask Me Help Desk - Load Center service cable size

Load Center service cable size

Installed a 125 Amp main breaker load center 190' from main. I Have already roughted in part of the run w/ 2" PVC conduit. Plan to run full length in 2". I estimate that approx. 80-90 Amps would be max load during normal usage.

Called a number suppliers about aluminum cable and got several different answers on the cable I needed to install. I want to make sure I get this right the first time.

BF

At that distance, for a 125 amp service using aluminum wire, you need at least 2/0... better yet 3/0. If you downsize the breaker which feeds the panel you will be able to use a smaller wire.

Thanks for response. This is my point exactly: " you need at least 2/0.....better yet 3/0." 4/0 has also been recommended. This location will have a 240v 30A pump, and a 30A motor and numerous outlets and lights. My concern is having enough volts at this LC box. I want to insure I do not have lights flickering each time the pump turns on.

Thanks.

BF

Try this to see where I get my information... Wire Size Calculator

Thanks Missouri Bound. That is a great calc to have. I found several calculators on Southwire's website. 2/0 works on one but does not work on the other?

I see what is going on now. I cannot find anyone who sells 3/0. Some suppliers where suggesting 2/0, some were recommending 4/0 because that is what they stock. I'm assuming that if I have a 125 amp breaker and box, and should I ever need 125 amps, it would be best to go w/ the 4/0 if I cannot find any 3/0?

BF

I just need to ask:

Is this underground? If so, wire must be rated for wet locations.

Is it for a detached building?

4/0 is probably the best way to go. Don't forget to pull a ground as well. You will need to isolate the neutral from the panel (remove the bonding screw / strap) and add a ground bar if not included. If this is an outbuilding you will need a ground rod as well at that location.

Quote:

Originally Posted by kiss

i just need to ask:

Is this underground? If so, wire must be rated for wet locations.

Yes, underground in 2" pvc conduit. I wound up getting 200 amp
mobile home service cable. I was informed this was suitable.

Is it for a detached building?

Yes. Approx. 190'

Boyfriend

Quote:

Originally Posted by Missouri Bound

4/0 is probably the best way to go. Don't forget to pull a ground as well.

I got 4/0-4/0-2/0-1/0 mobile home service cable Is the 1/0 the ground you are referring to or does there need to be another ground?

You will need to isolate the neutral from the panel (remove the bonding screw / strap) and add a ground bar if not included.

I have a GE main breaker load center box. It did not come w/ an equipment ground bus. Is it ok to remove the cross bar, gound left neutral/grnd side to box and attach supplied lug and attach 1/0 ground cable and all ground wires here. Connect 2/0 to right neutral bus and neutral branch circuits here. Or do I need to add a seperate equipment ground bus? It is a 12/24 box and I will not need more than 12 circuits.

If this is an outbuilding you will need a ground rod as well at that location.

This is an out building 190' from main. So I need to add ground wire and rod? I'm assuming solid copper wire. To get from LC box to earth can this ground run in the same conduit or does it need to run outside in insulated cable fastners to ground rod?

Thanks for the help!

BF

Quote:

Originally Posted by Missouri Bound

If this is an outbuilding you will need a ground rod as well at that location.

What is optimum size ground for this 125Amp box. Can I run an insulated ground wire through the same service cable conduit outside to earth or does it need to be separate?

Thanks!

BF

So let me see if I got this right. You are using the service cable, not individual wires, right? Well the #1 is your ground from the main to the sub. In addition to that you will need a ground rod at the sub location, with #2 wire.

Quote:

Originally Posted by Missouri Bound

So let me see if I got this right. You are using the service cable, not individual wires, right?

Yes. 2 load, neutral, and ground.

LC box came w/ extra lug and ground screw. Is it okay to remove crossbar. Install lug on bus, opposite of nuetral bus, and install ground screw to this bus to ground box, and install #1 ground to this bus. Or would it be better to install a separate equipment ground bus inside box?

Quote:

Originally Posted by Missouri Bound

In addition to that you will need a ground rod at the sub location, with #2 wire.

Can this ground cable be insulated and run inside the same conduit to get outside to the ground rod? Or does it need be run separate from the service cable?

Thanks!

BF