Fixed conductors having insulating coverings and operating at over 300 volts to ground, and bare conductors at all voltages shall, unless guarded as required in § 39.214 (relating to guarding conductors) be so isolated by elevation, as required by § 39.199(a) (relating to guarding or isolating live parts), that no person may inadvertently come or bring conducting objects in contact with them.
34 Pa. Code § 39.213
This section cited in 34 Pa. Code § 39.212 (relating to mechanical and thermal protection).