What must be used when calculating noncoincident loads of motor or air-conditioning equipment?

When calculating noncoincident loads for motor or air-conditioning equipment, the standard practice is to apply 125 percent of the highest individual load, which provides a buffer to account for potential fluctuations in demand and ensures that the electrical system can handle the load safely and efficiently. This practice reflects the National Electrical Code (NEC) guidelines, which aim to enhance safety and reliability, particularly for systems subjected to varying operational conditions.

In the case of motors, the 125 percent rule is particularly important due to the potential for high inrush currents during startup, which can exceed the normal running current. By using 125 percent of the larger load, you are accommodating these variations and ensuring that the circuit can handle both continuous and peak load demands without risk of overload.

This approach helps maintain a margin of safety within electrical installations, thus reducing the likelihood of equipment failures or electrical hazards, translating to better performance and longevity of both the electrical system and the equipment being serviced.