(a) Each vault must be designed so as to minimize the entrance of water. Nevertheless, vault equipment shall be designed to operate safely, if submerged.
(b) A vault containing gas piping may not be connected by means of a drain connection to any other underground structure.
(c) All electrical equipment in vaults must conform to the applicable requirements of Class 1, Group D, of the National Electrical Code, NFPA 70 (as described in section 10.3 of this Title).