Interpretation ID: nht89-1.86

TYPE: INTERPRETATION-NHTSA

DATE: 05/08/89

FROM: DAN TREXLER, -- THOMAS BUILT BUSES INC SPECIFICATIONS ENGINEER

TO: ERIKA Z. JONES -- OFFICE OF CHIEF COUNCIL NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 08/30/89 FROM STEPHEN P. WOOD -- NHTSA TO DAN TREXLER; REDBOOK A34 [7]; STANDARD 105; STANDARD 108; STANDARD 121; STANDARD 217

TEXT: Dear Ms. Jones,

We, as well as other body companies, have received requests to install a master electrical disconnect switch on many buses. This switch disconnects the entire electrical system from the battery(ies) (i.e., battery cut-off switch).

The requests have been both in the form of state requirements (on school buses) and by individual customers. Additionally, it is a recommendation contained in the Baseline Advanced Design Transit Coach Specifications (UMTA "White Book") (Part II, page I I-75, section 3.6.5.3).

When this switch is turned to the "off" position, it renders inoperative the warning signals (to the driver) required by FMVSS 105, 121 and 217. It also inactivates the hazard warning flasher required by FMVSS 108.

Would the installation of such a switch constitute a safety related hazard or noncompliance if, a) it is accessible to the seated driver or, b) it is remotely located in the battery or engine compartment without ready access to the driver?

We would appreciate an interpretation of this matter at your earliest convenience.

Sincerely,