Pennsylvania Code
Title 34 - LABOR AND INDUSTRY
Part I - Department of Labor and Industry
Chapter 39 - SAFETY STANDARDS-GENERAL
Subchapter B - ELECTRIC SAFETY
SWITCHBOARDS AND PANEL BOARDS
Section 39.246 - Guarding current-carrying parts

(a) Switchboards and panelboards having exposed current-carrying parts operating at over 150 volts to ground and not isolated by elevation at least eight feet above the floor shall when practicable be suitably enclosed in locked cabinets, screens, or rooms, or other enclosures to make them inaccessible to others than the authorized operator. Conducting floors about such boards shall be provided with a suitable insulating platform or mat so placed that no person may inadvertently touch live parts unless standing on the insulating platform or mat. Reference should also be made to §§ 39.199 and 39.238(a) (relating to guarding or isolating live parts; guarding live parts of switches and automatic cut-outs). If the circuit voltage exceeds 300 to ground this arrangement shall always be made.

(b) If switchboards or panelboards at voltage below 150 to ground are accessible to other than properly qualified operators, they should, if practicable, be enclosed in cabinets or screens as an effective precaution against accidental short circuits at times when no operation of the board necessitates the opening of the cabinet or screen. Reference should also be made to § 39.244 (relating to spacing and barriers against short circuit).

(c) Plug-type switchboards on constant-current systems, or if above 150 volts to ground, shall have no current-carrying parts exposed on face of boards, and plug connectors shall have current-carrying parts guarded as long as they are alive.

(d) Switchboards having no current-carrying parts exposed to at the face, that is, the working space, should be used in theaters and similar places where rapid handling is necessary, and the attention shall be given to signals or to other processes.

(e) Theater switchboards at any voltage, if having current-carrying parts exposed at the face, should, if practicable, be elevated, or guarded by suitable railings, to prevent contact with live parts by passersby.