Series lamps and devices in series circuits should always be treated as alive unless disconnected by absolute cut-outs or protected by the grounding of the circuit. Reference should also be made to §§ 39.401 -39.405.
34 Pa. Code § 39.442
This section cited in 34 Pa. Code § 39.441 (relating to general provisions); and 34 Pa. Code § 39.461 (relating to general requirements).