Interpretation ID: nht72-2.19

DATE: 08/11/72

FROM: AUTHOR UNAVAILABLE; E. T. Driver; NHTSA

TO: Imperial Fire Apparatus

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of July 21 to Mr. (Illegible Words) Truck Body and Equipment Association, Inc., concerning interpretations of FMVSS No. 108 requirements relating to fire trucks.

The answers to the questions you asked are as follows:

I. Flashing Identification, Clearance, and (Illegible Word) Lights. (Illegible Word) calls for all identification clearance, and (Illegible Words) to be wired into a motor driven (Illegible Word) with a selector switch for "steady on" or "flashing". Is this procedure allowable?

(Illegible Word). Flashing side (Illegible Words), but not clearance and identification lamps, are permitted by FMVSS No. 108.

II. Flashing Lights.

Customer calls for a second set of identification and clearance lamps ((Illegible Words) and power) to be mounted adjacent to the existing lighting. This second set of lights is to be wired into a motor driven flasher with a separate control switch located in the cab. Is this procedure allowable?

Yes. The additional or supplemental lamps are permitted by FMVSS No. 108, and flashing these additional lamps is (Illegible Word) in non-compliance with the standard. Regulations of individual states may, however, be applicable to this arrangement.

III. Battery Disconnect Switch.

On many trucks, the battery is wired into a master switch whereby the battery can be completely isolated from the electrical system. When this switch is in the "off" position, all light switches including identification, clearance, and four (4) way hazard flashers become in-operative. With the vehicle's engine shut down, the four (4) way hazard signals may only be activated by turning (Illegible Word) to "on" and turning four (4) way hazard switch to "on". Is this installation in compliance with SAE (Illegible Words) 4.21. If there are lights that must be activated by a single driver action, could you please note them.

This installation is in compliance with the requirements of FMVSS No. 108, providing the master switch is separate from the ignition switch and the hazard warning signal lamps will flash with the master switch on and the ignition switch off.