If natural gas is available at the site, a generator set fueled by natural gas is preferred to eliminate fuel storage equipment and the associated problems.

If natural gas is not available, the standby generator shall be driven by diesel fuel. The engine shall be of the general purpose, stationary direct injection, four-cycle, compression ignition type with radiator cooling. Maximum speed of the engine shall not exceed 1,800 rpm. The generator shall be of the self-regulated type utilizing a brushless excitation system.

All accessories needed for proper operation of the engine/generator set shall be provided. These shall include a starting battery, battery charger, jacket water heater, critical area type exhaust silencer with flexible exhaust connections, vibration isolators, antifreeze, a dual-wall, sub-base fuel oil storage tank, engine generator control panel, generator output circuit breaker and an automatic transfer switch. The engine/generator set shall be housed in a sound attenuating, weatherproof enclosure.

The engine/generator set shall be mounted on a raised concrete pad/foundation with anchored mounting bolts. Vibration isolators shall be provided.

Acceptable standby generator manufacturers: Caterpillar, Kohler, Onan. (Design Guideline DG-08 § 18.2, dated August 2006)