Description / Abstract:
This SAE Recommended Practice covers the design and application
of primary on-board wiring distribution system harnessing for
surface vehicles. This document is intended for single phase
nominal 120 VAC circuits that provide power to truck sleeper cab
hotel loads so that they may operate with the main propulsion
engine turned off. The power supply comes from alternative sources
such as land-based grid power, DC-AC inverters and auxiliary power
generators. The circuits may also provide power to improve vehicle
performance through charging batteries or operating cold-weather
starting aids.
This document is not intended to provide guidance for electric
or hybrid electric vehicle wiring circuits. Refer to SAE J1673 for
high voltage automotive wiring assembly design.
Engine block heaters are 120 VAC devices that are used on a
multitude of vehicle platforms in addition to trucks with sleeper
cabs. Generally, the engine block heater circuit is wired
independent of hotel loads. SAE J2698 does not apply to
independently wired engine block heater circuits. Engine block
heaters that are integrated with hotel loads are subject to the
guidelines in this recommended practice.
It is understood that drivers may choose to operate 120 VAC
devices with the truck moving or at rest. For example, a passenger
may operate the microwave or watch television and need to operate
an inverter. The environment that these devices are operated in can
also vary with exterior ambient temperature extremes. Exposure to
oil and vibration are other elements that typical household 120 VAC
wiring would not normally be exposed to; therefore, the
construction of this power distribution is made more robust for a
mobile trucking environment. Driver interaction with the 120 VAC
power through use of appliances or connection of cord sets requires
special attention to safety aspects dictated in regulatory
standards from Nationally Recognized Testing Laboratories (NRTLs)
approved labs like Underwriter's Laboratories (UL), Canadian
Standards Association (CSA) or from the National Electric Code
(NEC) that are not common practice with typical 12 VDC vehicle
wiring. This recommended practice supports that all electrical
materials, devices, components, appliances, fittings and equipment
shall be Listed, Labeled or Certified to UL and CSA standards and
shall be connected in an approved manner when installed. Detailed
requirements are listed hereafter.