NCCER Residential Wiring Practice Exam 2025 – Comprehensive Resource to Master Your Certification!

The correct approach for sizing a branch circuit for a wall-mounted oven or counter-mounted cooking unit is to use 100 percent of the nameplate rating. This means that the circuit must be able to handle the full load as specified by the manufacturer to ensure safe and efficient operation of the appliance.

Using the full nameplate rating is crucial because appliances such as ovens can draw significant current when they are operating. If the circuit were sized based on a lower percentage, like 75 percent or 90 percent, there is a risk that the circuit may not adequately supply power during peak operation, leading to potential overheating or tripping of breakers. Similarly, sizing at 120 percent is typically used in different contexts, such as for continuous loads, but for residential cooking appliances, sticking with the 100 percent nameplate rating is essential. This conforms to the National Electrical Code (NEC) requirements and supports safe installation practices for kitchen appliances.