30 CFR § 18.29 Access openings and covers, including unused lead-entrance holes. (a) Access openings in explosion-proof enclosures will be permitted
only where necessary for maintenance of internal parts such as motor brushes
and fuses. (b) Covers for access openings shall meet the same requirements as
any other part of an enclosure except that threaded covers shall be secured
against loosening, preferably with screws having heads requiring a special
tool. (See Figure 1 in Appendix
II.) (c) Holes in enclosures that are provided for lead entrances but
which are not in use shall be closed with metal plugs secured by spot
welding, brazing, or equivalent. (See Figure 10 in
Appendix II.)
