46 C.F.R. § 112.25-3 Normal source for emergency loads.
Title 46 - Shipping
(a) The normal source for emergency loads must be the ship's service generating plant. (b) The power from the ship's service generating plant for the emergency loads must be supplied to the emergency switchboard by an automatic transfer switch located at the emergency switchboard.
Title 46: Shipping
PART 112—EMERGENCY LIGHTING AND POWER SYSTEMS
Subpart 112.25—Emergency Systems Having an Automatic Starting Diesel Engine or Gas Turbine Driven Emergency Power Source as the Sole Emergency Power Source
§ 112.25-3 Normal source for emergency loads.