Compressed Air Systems

Voltage and Amperage Calculator

Voltage and Amperage Calculator

Voltage and Amperage Drop Calculator

Compressed Air Systems has compiled this chart as a reference. If the distance from your main panel will drop the voltage supplied below the minimum operating voltage of your compressor’s system, you may need to look into a booster to raise the voltage back up to the operating range.

Note: This sheet is meant only as a guide. Site visits and evaluations are still recommended to ensure the proper compressor package is quoted for the application. Voltage drops of more than 3% can fall outside the operating parameters of electrically driven equipment.

Voltage Drop

All amperage and voltage drops are based on 2011 NEC, Article 430, Part III, Copper Wire 75C, Ampacity THW, THHN-THWN, XHHW NEC Table 3101.15

Temperature Range
Wire Size Distance from Main Panel
Amperage Flow
Approximate Voltage Drop
at Maximum Amperage

Motor Amperage Draws

Based off an average max amperage draw across several different motor manufacturers as of 2018.

Motor HP Phase Max Amperage Draw
at 200 Volts
Max Amperage Draw
at 208 Volts
Max Amperage Draw
at 230 Volts
Max Amperage Draw
at 480 Volts
5 1
5 3
7.5 1
7.5 3
10 1
10 3
15 3
20 3
25 3
30 3
40 3
50 3