My basic approach, may be overkill
Use your amps 4 Ohm rating, max current
Mine is 220 W, V = sqrt(4 x 220) 30 V
I = 7.3 A
I use a max V drop of 2%, in this case 0.6 V
Z = 0.6/7.3 = 0.08 Ohm or less required
Assume length is 20' x 2 = 40' loop
NEC table lists values per 1000'
Z = 40/1000 x Z from table = 0.08
Or Z from table = 1000 / 40 x 0.08 = 2 Ohm
From the table using Z at 0.85 pf (30 deg)
Use PVC values
You need ~ 2 Ohm or less.
12 AWG 1.7 Ohm
Assume 35' rum 70'
Z required = 1000 / 70 x 0.08 = 1.15
You may want to upsize to 10 AWG at 1.1 Ohm
Power loss will be
If 10 W 8 Ohm, V = .9, I = 1.1
Ploss ~ 1.1^2 x 0.08 ~ 0.1 W or 1% or less
View attachment 185034
