Pennsylvania Statutes Title 52 P.S. Mines and Mining § 690-304. Protection against shock

(a) Electrical work.--No electrical work shall be performed on low-voltage, medium-voltage or high-voltage distribution circuits or equipment except by a qualified individual or by an individual trained to perform electrical work and to maintain electrical equipment under the direct supervision of a qualified individual. Disconnecting devices shall be locked out and suitably tagged by the individuals who perform the work, except that, in cases where locking out is not possible, the devices shall be opened and suitably tagged by such individuals. Locks or tags shall be removed only by the individual who installed them or, if the individuals are unavailable, by an individual authorized by the operator or the operator's agent.

(b) Insulating materials.--Mats of rubber, insulated platform or other suitable insulating materials shall be provided at all stationary transformers, rectifiers, motors and generators and their controls, except portable and mobile equipment. Gloves or mats of rubber or other suitable insulating material shall be provided by the operator and used by qualified individuals when energized parts of electrical apparatus have to be handled for the purpose of adjustment.