A feeder circuit with a continuous load of 16A and a noncontinuous load of 10A should use an overcurrent protective device sized at what?

To determine the appropriate size of the overcurrent protective device, it's essential to consider both the continuous and noncontiutous loads as they impact the overall sizing of the circuit's protective measures.

A continuous load is defined as a load that continues for three hours or more, while a noncontinuous load does not have this duration requirement. According to the National Electrical Code (NEC), the continuous load should be calculated at 125% of its rating to ensure safety and accommodate possible surges in demand.

In this case, the continuous load is 16A. When you apply the 125% rule to this continuous load:

16A x 1.25 = 20A.

Next, the noncontinuous load of 10A can be added to this calculated value. The total load used to size the overcurrent protection is therefore:

20A (for the continuous load) + 10A (for the noncontinuous load) = 30A.

This calculation indicates that an overcurrent protective device rated at 30A is adequate and compliant with code requirements. Therefore, it ensures that during typical operation, the device will protect the circuit without tripping unnecessarily, allowing for both steady-state operation and accommodating variations in electrical demand.