Where can the value of available fault current for service equipment be obtained?

The value of available fault current for service equipment is primarily obtained from electric utilities. This is because electric utilities are responsible for the design and operation of the electrical supply to buildings and other facilities. They have the necessary data regarding the capacity and characteristics of the distribution system, including how much fault current can be expected at a given service point. This information is critical for safely designing and selecting protective devices, including circuit breakers and fuses, that need to withstand potential fault conditions.

While electrical maintenance manuals, building codes, and manufacturer specifications may provide useful information related to electrical installations and devices, they do not typically contain the specific data on available fault current that pertains directly to the service equipment in question. Manufacturer specifications usually detail the performance characteristics and ratings of specific equipment but do not give the fault current levels that would be required for systems interconnected to utility sources. Thus, consulting with the electric utility is the most reliable method for obtaining accurate fault current values relevant to safety and compliance with NEC standards.