30 CFR § 28.40 Construction and performance requirements; general.
(a) MSHA shall issue approvals for fuses for use with direct current
in providing short-circuit protection for trailing cables, when such fuses
have met the minimum construction, performance, and testing requirements set
forth in this subpart.
(b) Fuses submitted to MSHA for approval will not be accepted unless
they are designed on sound engineering and scientific principles, constructed
of suitable materials, and evidence good workmanship.
(c) Fuses may be single-element or dual-element in type, however,
they shall be capable of interrupting any direct current within a range from
the ampere rating of the fuse under consideration for approval up to 20,000
(d) MSHA shall accept the fuse size and ampere rating as specified in
the Underwriters Laboratories, Inc., standard for alternating current fuses
(UL-198), which is hereby incorporated by reference and made a part hereof.
This document is available for examination at the U.S.
Department of Labor, Mine Safety and Health Administration, Approval
and Certification Center, 765 Technology Drive, Triadelphia, WV 26059,
and copies of the document are available from COMM 2000, 1414 Brook
Drive, Downers Grove, IL 60515; Telephone: 888-853-3512 (toll free);
(e) Fuses shall be capable of completely interrupting a current
within 30 milliseconds after initial current interruption, and shall not show
any evidence of restriking after 30 milliseconds.
(f) The blown fuse shall show only superficial damage.