At what percentage of the total connected load should fixed electric space-heating loads be calculated?

Fixed electric space-heating loads should be calculated at 100% of the total connected load. This is because space-heating systems are essential for maintaining a comfortable environment, and their full capacity must be considered to ensure that the electrical system can handle the maximum demand during peak heating times. Calculating at 100% allows for accurate load management and ensures that the electrical infrastructure is appropriately sized to prevent overloads, ensuring safety and efficiency.

Calculating fixed space-heating loads at a lower percentage could lead to underestimating the load during critical periods, potentially risking system performance and safety. Thus, adhering to the 100% calculation is a standard method outlined in the National Electrical Code (NEC) for ensuring that all heating systems operate effectively without compromising safety or reliability.