(2) Internal Combustion Engines as Prime Movers
(a) On-Site Fuel Supply. Where internal combustion engines are used as the prime mover, an on-site fuel supply shall be provided with an on-premises fuel supply sufficient for not less than 2 hours' operation of the system.
(b) Fuel Transfer Pumps. Where power is needed for the operation of the fuel transfer pumps to deliver fuel to a generator set day tank, this pump shall be connected to the emergency power system.
(c) Public Gas System, Municipal Water Supply. Prime movers shall not be solely dependent on a public utility gas system for their fuel supply or municipal water supply for their cooling systems.
Exception: Where approved by the authority having jurisdiction, the use of other than on-site fuels shall be permitted where there is a low probability of a simultaneous failure, of both the off-site, fuel delivery system and power from the outside electrical utility company.
(d) Automatic Fuel Transfer. Where dual fuel supplies are used, means shall be provided for automatically transferring from one fuel supply to another.