Check my sub panel plan

[chevroletfreak]

All wiring and panels are within the same 30x50 metal building.

The current service panel is 200 amps.

I am adding a subpanel on the opposite end of the building that I want to have 100 amps.

The length of the run from panel-new panel is approximately 90'. Total length needed is estimated at 360'. 90 (Hot A) + 90 (Hot B) + 90 (Neutral) + 90 (Ground).

I have calculated the voltage loss and have concluded the correct wire for this length is 1 AWG copper in order to maintain less than 3% loss.

The subpanel neutral and ground will be isolated.

I believe a separate gound rod(s) is not necessary for the new subpanel.

I intend to run the same 1 AWG THHN/THWN-2 copper back to main panel for both legs, the neutral and the ground in 1-1/2" schedule 40 pvc.

Do my calculations for gauge compute?
How do I calculate the appropriate ground size?
Is conduit necessary if the wires are setting on an open ledge? (Consider the potential of rodents)

Anything else I may be overlooking?

 

[Aceman]

No, it doesn't compute.

I'd recommend #3 hots/neutral and a #8 green.

We'd run 1 1/4" emt for this feeder in a metal building or possibly MC cable if protected from physical damage.

 

[chevroletfreak]

I used southwires' calculator. I used 100' run of 120v that has 100 amps and <3% loss.

 

[Pwrgeek]

I used southwires' calculator. I used 100' run of 120v that has 100 amps and <3% loss.

Use 240V. If you keep everything pretty balanced between legs then there should be very little neutral current.

 

[pattenp]

Aceman is dead on with three #3 Cu and one #8 Cu in 1.25" EMT.