Pennsylvania Code
Title 34 - LABOR AND INDUSTRY
Part I - Department of Labor and Industry
Chapter 39 - SAFETY STANDARDS-GENERAL
Subchapter B - ELECTRIC SAFETY
ROTATING EQUIPMENT
Section 39.115 - Grounding noncurrent-carrying parts

(a) Exposed noncurrent-carrying metal parts of rotating electrical supply equipment shall be permanently grounded in accordance with the requirements for grounding provided in § 39.103 (relating to protective grounding).

(b) If machine frames, such as those of series are light generators or direct current railway generators, are necessarily ungrounded, suitable insulating floors, mats, or platforms providing good footing shall be so placed that no person may readily touch the machine frame unless standing on such floor, mat, or platform.

(c) If two or more machines, either of which operates at over 150 volts to ground, are mechanically coupled together and the operator is able to touch the frames of more than one at a time, the frames of all such shall be permanently grounded or bonded together electrically. This provision may be waived under the following circumstances:

(d) Exciters and auxiliary circuits electrically connected to generators or other machines over 750 volts to ground (with frames ungrounded) shall be installed, protected, and identified as machines and circuits of the same voltage as that of the machine for which they are auxiliaries. Reference should also be made to § 39.132 (relating to grounding low voltage circuits of instrument transformers).