In feeder sizing, which type of load must be increased by 125%?

In feeder sizing, which type of load must be increased by 125%?

• A. Noncontinuous
• B. Continuous
• C. Both
• D. Neither

Answer: (B)

The concept tested is how continuous loads are treated when sizing feeders. Continuous loads are defined as those that run for 3 hours or more in a 24-hour period. To prevent overheating and provide adequate margin for long-term operation, the ampacity for continuous loads is increased by 125% when sizing feeders and services. Noncontinuous loads do not get this increase because they aren’t sustained long enough to cause the same heating risk. In practice, you size the feeder by adding 1.25 times the continuous-load amperage to the actual amperage of the noncontinuous loads. For example, if there is a continuous load of 40 A and a noncontinuous load of 20 A, the feeder would be sized for 1.25 × 40 + 20 = 50 + 20 = 70 A. So the type that must be increased by 125% is the continuous load.

The concept tested is how continuous loads are treated when sizing feeders. Continuous loads are defined as those that run for 3 hours or more in a 24-hour period. To prevent overheating and provide adequate margin for long-term operation, the ampacity for continuous loads is increased by 125% when sizing feeders and services. Noncontinuous loads do not get this increase because they aren’t sustained long enough to cause the same heating risk.

In practice, you size the feeder by adding 1.25 times the continuous-load amperage to the actual amperage of the noncontinuous loads. For example, if there is a continuous load of 40 A and a noncontinuous load of 20 A, the feeder would be sized for 1.25 × 40 + 20 = 50 + 20 = 70 A.

So the type that must be increased by 125% is the continuous load.