Where the electrical supply meets the reliability standard the governing code requires - usually a dedicated feed arranged so it cannot be isolated by the same event as the building supply, often with a secondary source such as a generator. Where that cannot be demonstrated, a diesel pump is required.

To exceed the pump's maximum brake power anywhere on its curve, not just at the design duty point. During a fire the pump can be driven well out along the curve as more outlets open, and a motor sized only for the nominal duty will trip at exactly the moment it must not.

Simplicity and cost. No fuel storage or degradation, no exhaust routing, no combustion air, less heat rejection, a smaller plant room and a considerably lighter test regime. Where the supply justifies it, an electric set is easier and cheaper to own throughout its life.

The same as the wider family - horizontal split case for high flow with serviceable access, vertical inline where space is limited, and vertical turbine where the water supply is a tank or reservoir below the pump. The drive choice and the pump type are separate decisions.

Yes. Regular no-flow running and annual flow testing against the pump curve remain required, with results recorded, though the routine is lighter than for a diesel set because there is no engine, fuel or battery system to exercise and verify.

Only within what the governing code and the listing permit, and generally not in the way it would be used on a service pump. A fire pump must deliver its rated performance on demand without dependence on additional electronics, so any drive arrangement has to be part of the listed assembly.

It is a listed fire pump controller, not a general motor starter, and it handles automatic starting on pressure drop, manual start, alarm signalling and supervision of the supply. The controller is as much a code-listed item as the pump and motor, and it cannot be substituted with ordinary switchgear.