Toll Free: +1-800-930-9414
Section 110.10 addresses the requirement for short-circuit current ratings, which are essentially a measurement of the amount of current that can flow through equipment without causing extensive damage. Short-circuit current rating is defined in Article 100.
Short-Circuit Current Rating. The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria.
When a short circuit occurs, a particular piece of equipment might be damaged, or parts of it might have to be repaired or replaced, but the damage would not extend significantly beyond the equipment. The short-circuit current rating indicates that the equipment will allow that much current to flow without a catastrophic failure. This requirement applies to equipment like motor controllers, some types of switches and the busing of a panelboard or a switchboard.
Some types of equipment are really only intended to interrupt normal levels of current, such as some controllers or a toggle switch or contactor for controlling lighting. That type of equipment is not required to have an interrupting rating but is usually required to have a short-circuit current rating.
© Hughes Associates,Inc. 2012