Overcurrent protection for feeders applies to which load combinations?

• A. Continuous and noncontinuous load combinations
• B. Continuous loads only
• C. Noncontinuous loads only
• D. Neither

Answer: (A)

The main idea is that the feeder’s overcurrent protection must account for all loads that could be on the feeder, including both those that run continuously and those that run for shorter periods. Continuous loads, because they operate for long durations, contribute more heating and are therefore treated with a 125% factor when sizing protection. Noncontinuous loads are added at their actual rating. By combining both types, you determine a protection level that safely handles the worst-case current, whether the continuous and noncontinuous loads occur together or not. This is why overcurrent protection for feeders applies to continuous and noncontinuous load combinations. For example, take a continuous load; its effect is multiplied by 1.25, then you add any noncontinuous loads at full value to get the required feeder protection.