I have a situation where we have an existing 480/277V 3000A switchboard that we are adding two buckets to. Except for the 3000A main all over current devices are fused switches. We have the option of adding fused switch buckets or circuit breakers. The existing gear does not have a label telling us what AIC it is rated. The main is rated 100KAIC and the fused switch buckets are rated 200KAIC. The existing plans call for 100KAIC bus but state the available fault current at 42KAIC. I have not received the real available fault current from the utility yet.
My question has to do with the rating of the board. It appears to be rated 100KAIC. The available fault current will probably come in around 20KAIC. If we install 42KAIC rated breakers, are we violating anything in a remodel condition like this?
