Lightning arresters when installed for the protection of utilization equipment may be installed on supply lines or service leads either within or without the buildings or inclosures containing the equipment to be protected, and the methods employed shall be in accordance with the rules governing the construction of overhead lines, supply stations, or utilization equipment, as they apply.
34 Pa. Code § 39.186
This section cited in 34 Pa. Code § 39.201 (relating to storage batteries, transformers and lightning arresters).