Pennsylvania Code
Title 34 - LABOR AND INDUSTRY
Part I - Department of Labor and Industry
Chapter 39 - SAFETY STANDARDS-GENERAL
Subchapter B - ELECTRIC SAFETY
PROTECTIVE ARRANGEMENTS OF EQUIPMENT
Section 39.103 - Protective grounding

(a) Grounding method. Lightning arresters, grounding, and all grounding of circuits, equipment or wire runways, intended to be a permanent and effective protective measure, shall be made in accordance with methods specified in §§ 39.61-39.70 (relating to methods of protective grounding).

(b) Grounding noncurrent-carrying metal parts. Electrical supply equipment, if operating at over 150 volts to ground, or if in hazardous locations, shall have their exposed noncurrent carrying metal parts, such as frames of generators, motors, and switchboards, and cases of transformers and oil switches, permanently grounded. References should also be made to §§ 39.115 and 39.159 (relating to grounding noncurrent-carrying parts; grounding noncurrent-carrying metal parts). When regulating voltage, generators or converters supplying circuits not exceeding 140 volts to ground are operated at not more than 180 volts, such generators or converters are considered not to exceed 150 volts to ground. Hazardous locations include those where dampness, acid fumes, explosives, inflammable gas, or flyings normally exist.

(c) Exemptions. Exposed noncurrent-carrying metal parts of electrical supply equipment operating on grounded direct current circuits or on series direct-current circuits may be left ungrounded if no inflammable gas is present, and if suitable insulating floors, platforms, or mats are used, so that no person may inadvertently come in contact with such ungrounded parts while he is standing upon any grounded surface, including floors not of insulating material; and further if suitable permanent insulating barrier guards are used so that a person may not, while touching the ungrounded parts at the same time inadvertently touch other machine frames or metallic fixtures not bonded to the parts in question. This provision shall not apply to the motor frame of a direct connected, motor driven, high tension, series generator sets in existing installations, when the generators have their frames insulated from ground, for operating reasons, and the motor frames are grounded, if it is impracticable to provide insulating barrier guards in the space available. Reference should also be made to § 39.115 (relating to noncurrent-carrying parts).

(d) If exposed noncurrent-carrying metal parts are not grounded they shall be suitably insulated from the ground and from neighboring grounded surfaces.