Question

What size branch-circuit conductors are required for a 40a resistance welder having a duty cycle of 30 percent? (use 60 degree terminations)

Answer 1

The size of the branch-circuit conductors required for a 40A resistance welder with a duty cycle of 30% would be 10 AWG conductors.

Step-by-step explanation:

The size of the branch-circuit conductors required for a 40A resistance welder with a duty cycle of 30% can be determined using the ampacity ratings provided in the NEC (National Electrical Code) Table 310.15(B)(16)

1. First, we need to determine the continuous load current. The continuous load is calculated by multiplying the rated current by the duty cycle. In this case, the continuous load current is 40A x 0.3 = 12A.
2. Next, we need to determine the appropriate conductor size. According to the NEC 2017, the ampacity for a conductor that's rated at 60°C (140°F) is 30A. Since the continuous load current of 12A is less than the ampacity rating, 10 AWG (American Wire Gauge) conductors would be suitable for this application.