12V power supply:
For 1 meter, choose 10 ohm resistor, power = 15W (line surface is about 50 degrees)
For 2 meters, choose 3 ohm resistor, power = 24W (line surface is about 50 degrees)
For 3 meters, choose 1.4 ohm resistor, power = 34W (line surface is about 50 degrees)
For 4 meters, choose 1 ohm resistor, power = 36W (line surface is about 45 degrees)
For 5 meters, choose 1 ohm resistor, power = 29W (line surface is about 40 degrees)
For 7 meters, choose 0.3 ohm resistor, power = 68W (line surface is about 45 degrees)
For 10 meters, choose 0.3 ohm resistor, power = 48W (line surface is about 50 degrees)
220V power supply:
For 2 meters, choose 588 ohms 220V/50W
For 5 meters, choose 120 ohms 220V/53W
For 10 meters, choose 74 ohms 220V/65W
For 15 meters, choose 30 ohms 220V/100W
For 20 meters, choose 20 ohms 220V/121W
For 30 meters, choose 30 ohms 220V/320W
50 meters, choose 2 ohms 220V/520W
80 meters, choose 0.6 ohms 220V/800W
For 120 meters, choose 0.3 ohms 220V/1.3KW