I have a Honda eu3000is which is rated at 2800W (3000W max for up to 30 mins) and am consider a 90-100' run to the 30A, 120V single phase APC UTS6H (.PDF) transfer switch that's connected to my main panel.

I originally envisioned a 10' run, but the 100' run would place this generator in a spot that's much easier for refueling and help keep it shielded from bad weather.

I've been trying various calculations of voltage drop that support 23.4A (i.e., 2800W / 120V) up to 100', but am not sure my numbers or assumptions are correct.

If I looked at AWG size resistances on Wikipedia, I see things like:

AWG Size Resistance (Ohms/ft)

10 0.000999

8 0.000628

6 0.000395

5 0.000313

4 0.000249

3 0.000197

2 0.000156

1 0.000124

1/0 0.0000983

2/0 0.0000779

3/0 0.0000618

4/0 0.000049

So, I thought Voltage drop could be calculated as:

Voltage drop = (Ohms/foot) × (length) × (current)

Which, in my case would give examples like:

10: 0.000999Ohm/ft x 100ft x 23.4A = 2.34V

8: 0.000628Ohm/ft x 100ft x 23.4A = 1.47V

6: 0.000395Ohm/ft x 100ft x 23.4A = 0.92V

5: 0.000313Ohm/ft x 100ft x 23.4A = 0.73V

4: 0.000249Ohm/ft x 100ft x 23.4A = 0.58V

. . .

Looking at other discussions, I may be doing something wrong with these numbers - plus, I don't know if there would be any problems using lower gauge wires with my (essentially) 30AMP run and connectors.

Figured I would use THNN/THWN through outdoor nonmetallic conduit from the outlet to the transfer switch, if that meets code.

My target is to minimize voltage drop for this little generator across the 100' span.

Thoughts or ideas welcome.

- wader