Let's begin with a review of the situation where you have one building, one fire pump, and one power source (from the utility). The major issue is that you will need to run a dedicated feeder from the service transformer (just after the metering equipment) to the fire pump. NEC 695.3 (A)(1) prevents you from coming off of the main service equipment.
Typical fire pump and jockey pump installation.
If your feeder is before the metering equipment, the utility will install a second set of meters on it. Initially, this is not a big deal. The owner simply has to pay an additional monthly meter charge......