Interpretation ID: nht71-2.28

DATE: 04/20/71

FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA

TO: Allied Chemical Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of March 24, 1971, requesting our interpretation of S4.5.2 of Motor Vehicle Safety Standard No. 208. You have asked whether the requirement of S4.5.2 that "all electrical circuits" must be monitored would mean that a bridgewire circuit in an electroexplosive device would have to be monitored. Our answer is that such a circuit must be monitored, although it should be noted that monitoring need not be continous, but may be designed to occur, for example, only when the ignition is in the "start" position.

Your letter points out several potential problems with the inclusion of such a bridgewire circuit among the monitored systems. We are giving consideration to the self-monitoring requirement in the light of the comments we have received, with a view to possible amendments that may be found advisable.