Electrical apparatus shall conform to Federal Motor Carrier Safety Regulation 393.77(c)(7).
Electrical insulation of the connecting cable shall withstand normal operating stresses in low
ambient air temperatures (down to minus 60°F) without cracking or loss of dielectric capacity.
All heater lead wires shall be installed without interfering with the vehicle component operation,
and without loose excess wire. Provisions for stowage of the cable shall be provided in the
vehicle cab. Heaters shall be furnished as follows:
(a) Coolant heater, 1500-watt minimum rating, shall be installed in the engine block or
lower, coolant inlet hose. An engine thermostat with an operating range of 170°F to
195°F shall be installed.
(b) Immersion type engine oil heater, 300-watt minimum rating, with 170°F to 195°F
thermostat, shall be installed in the oil pan through any convenient opening.
(c) Battery heater shall have a capacity adequate to maintain the battery electrolyte at a
temperature of not less than l0°F during vehicle exposure in ambient air
temperatures as low as minus 60°F, and shall embody a thermostat to limit the
temperature of the electrolyte to not more than 80°F.
(d) Hydraulic fluid reservoir heater shall have a capacity to maintain the hydraulic fluid
at a temperature of not less than l0°F during vehicle exposure in an ambient
temperature as low as minus 60°F, and shall embody a thermostat to limit the
temperature of the hydraulic fluid to not more than 75°F.
(e) A fuel warmer or pre-heater shall be provided for diesel engines to prevent clogging
of fuel filters due to wax crystallization in the fuel. The fuel warmer shall use
engine coolant to transfer sufficient heat to the diesel fuel to heat it from an inlet
temperature of minus 40°F to an outlet temperature of plus 9°F, with a flow rate not
less than the maximum fuel demand of the engine fuel system. A coolant shutoff
valve shall be provided for the coolant inlet side of the fuel warmer unit.
3.4.2 Electrical system. The electrical system shall be in accordance with Federal Motor
Carrier Safety Regulations 393.27 through 393.31 and 393.33.
* 126.96.36.199 Starting system. For diesel engine driven vehicles, a 12- or 24-volt starting system,
with 12-volt direct current (dc) lighting system and not less than a 60-ampere alternator shall be
furnished. Engine starting equipment shall include an ether starting system, a glow plug or
electric grid heater. If an ether starting system is furnished in lieu of a glow plug or grid heater,
it shall be of the measured shot type. Measured shot type ether systems shall be key operated or
manually operated from the driver's compartment, and shall be inoperative with the engine
warm. Complete provisions for an ether reservoir of not less than 12 fluid ounces shall be
furnished. A reservoir need not be furnished.