Definition of KAIC

By G.D. Palmer
Most home circuit breakers are rated in amperes, not kilovolt-amperes.

KAIC is an acronym used by electricians to refer to the ability of a circuit breaker to withstand a short circuit or overload. Large industrial circuit breakers often include a rating in KAIC that indicates the circuit size with which they are compatible. Choosing the correct breaker for your system prevents serious problems if there is a short.


KAIC stands for "Kilo Ampere Interrupting Capacity," but is occasionally written as "Thousand Ampere Interrupting Capacity" in some textbooks and wiring diagrams. Individuals from the U.S. are more likely to use the “thousand ampere” variation. “Kilo-ampere” is most frequent in Canada, the UK, Australia and other English speaking countries that fully use the metric system.


A kilo-ampere is a measurement equivalent to one thousand amperes, units of electrical current that represent the flow of electrons through a circuit over the course of one second. One ampere is equivalent to one coulomb per second. You can measure the number of amperes in a circuit using an ammeter.

Circuit Interrupting Capacity

Circuit breakers are designed to protect the circuit from damage in case of a short circuit or circuit overload. They can withstand only a certain amount of current and work by discontinuing the electrical flow when that limit is reached. All circuit breakers have an interrupting capacity rating, usually expressed in amperes, or AIC. large circuit breakers used in commercial and industrial applications may be rated in KAIC. If you install a circuit breaker with a KAIC that is too low for the circuit, it may not be able to protect the circuit from damage if overloaded.

Amp Traps

Electricians can extend the KAIC of a circuit breaker by adding amp traps. These devices are current-limiting fuses that open a faulted circuit before that circuit can reach a level of current greater than the circuit breaker rating. Amp traps do not work on their own and are always be used in conjunction with a main circuit breaker or standard fuse.

About the Author

G.D. Palmer is a freelance writer and illustrator living in Milwaukee, Wis. She has been producing print and Web content for various organizations since 1998 and has been freelancing full-time since 2007. Palmer holds a Bachelor of Arts degree in writing and studio art from Beloit College in Beloit, Wis.