Surge current capacity is the maximum amount of surge current that a surge protector can pass for a single surge event. This level is used to indicate the protection capacity of a particular surge protector. For example, in a high exposure area with a high likelihood for lightning, a larger surge current capacity might be desired. But, be aware that surges have natural limitations and that larger surge current capacity tends to add redundancy rather than the implied ability to handle an extremely large surge. For example, an entire lightning strike cannot go through wire; much like a fire hose has difficulty shooting through a soda straw. Realistically, surge protectors do not need to be sized for entire lightning strikes. But, there are valid reasons for adding excess surge current capacity for redundancy reasons.
The surge protection industry uses kiloamperage (kA) as a measure of the products surge current capacity. kA ratings at or above 10kA (10,000 Amperes) are generally acceptable.