Storage battery rooms shall be lighted, if practicable, from outside lamps. If lamps are inside, only incandescent electric lamps in keyless porcelain or composition sockets, controlled from points not exposed to battery vapor, shall be used.
34 Pa. Code § 39.126
This section cited in 34 Pa. Code § 39.85 (relating to general requirements); 34 Pa. Code § 39.121 (relating to applicability); and 34 Pa. Code § 39.201 (relating to storage batteries, transformers and lightning arresters).