New York State Master Electrician Practice Exam 2026 - Free Electrician Practice Questions and Study Guide

The demand factor for marina load calculations for shore power receptacles is determined based on the idea that not all receptacles will be used simultaneously at their full capacity. The National Electrical Code (NEC) provides guidance on demand factors to use for different types of loads, including marinas.

In the case of 45 shore power receptacles, the demand factor typically applied according to the NEC guidelines is 50%. This means that, when calculating the total electrical load for the marina, only 50% of the receptacles are expected to be in use at any given time. This approach helps ensure that the electrical system can manage peak loads without overloading the infrastructure.

Therefore, the choice of 50% as the demand factor is accurate because it reflects realistic usage patterns and helps with appropriately sizing the electrical infrastructure to accommodate peak demand while maintaining safety and efficiency.