Motors shall be of open drip-proof construction NEMA Design B, constant speed poly-phase, squirrel-cage induction type, having normal starting torque with low starting current.

The pumps shall start and stop automatically depending on system demand and even though the system is designed to avoid starts and stops in quick succession, frequent starts and stops will happen. As the effective life of a motor depends on the number of starts, and as it may be difficult to get custom-made motors in the lower horsepower ranges, as an insurance against premature failure, insulation for motors shall be specified as follows: Class F insulation with Class B temperature rise, that is, 80°C above the ambient temperature of 40°C.

It is recognized that such motors will cost more, and availability has to be checked with manufacturers.

Motors shall have a service factor of 1.0.

Motor voltage characteristics shall be as indicated under WSSC 11.125.240, Utilization voltage.

Motors 50 hp and above shall have built-in space heaters with thermostats rated at 120V, 1Ø, and are to be controlled by a normally closed auxiliary contact of the motor starter. Power for the space heater may be from the control power transformer in the starter or from the lighting panel.

Medium voltage motors shall be specified with terminal boxes of adequate size to accommodate lightning arrestors and surge capacitors in addition to cable terminations.

Motors and pumps of the highest efficiency available in their capacity range shall be specified.

The minimum motor horsepower requirement shall be determined by the consultant and given in the specifications. However, the pumping unit, including the selection of a proper size motor (the motor should not be overloaded at any point along the pump performance curve) shall be specified to be the responsibility of the pump manufacturer. This shall also include any variable speed devices in case of variable speed drives.

Acceptable Manufacturers: Continental, General Electric, Ideal, Teco-Westinghouse, or U.S. Motors. (28-ME-DG-02 § 6.2)