Master Electrician Practice Exam 2025 – Comprehensive All-in-One Guide to Master Your Certification!

To determine the demand load on the service-entrance conductors for an 18 kW residential electric range, one must apply the principles set forth in the National Electrical Code (NEC) regarding demand calculations for household cooking appliances.

According to NEC guidelines, for residential electric ranges, a demand factor can be established based on the total rating of the appliance. While an 18 kW range indeed has a maximum demand of 18 kW, the NEC allows for a reduction in this demand when calculating the load for service-entrance conductors. Specifically, the NEC provides that for cooking appliances, the first 12 kW is taken at 100%, and any additional load above this has a different demand factor.

In this case, for an 18 kW range, the first 12 kW is counted entirely, while the excess 6 kW (from 12 kW to 18 kW) is considered at a reduced demand factor of 33% according to the NEC recommendations for demand calculations. Thus, this additional 6 kW contributes 2 kW (33% of 6 kW), bringing the total calculated demand load to 12 kW + 2 kW = 14 kW.