AIC is an abbreviation for Amps Interrupting Capacity, also known as Amps Interrupting Rating, which is the maximum number of surge amps that can be served to the equipment and still safely trip off when the amperage gets too high. It can be found on panelboards, also called distribution boards or breaker panels, and panel circuit breakers.
The AIC is typically 10kA, meaning 10,000 amps, or 20kA, but can be as little as 5kA, with the higher ratings costing more. This amount is in addition to the sustained current rating, which could be 200 or 1,200 amps, and it is a safety rating separate to the nominal load rating of the panel. The National Fire Protection Association's National Electric Code states that equipment must be rated equal to or higher than the available surge current and any amount below this can become a safety hazard.
In the U.S., panel boards are usually placed in two columns and live electrical parts are hidden for safety reasons. They are often placed in closets, the attic, basements or garages because of their aesthetics and also for security reasons. External installation requires specialized equipment and stricter installation practices to keep them safe. Larger buildings, such as schools, hospitals and entertainment venues, will have multiple different panel boards dedicated to each area or for each building.