Grounding Clamps - hdbk109220040063

DOE-HDBK-1092-2004

4. For further information on the construction of personnel protective grounds, refer to

Section 7.5.

4.15.3 GROUNDING CLAMPS

Grounding clamps used in personnel protective grounds are manufactured specifically for this

use. The size of grounding clamps shall match the size of conductor or switchgear bus being

grounded.

The ground clamp also shall be rated to handle the full capacity of the available fault currents.

Fault currents can typically range in magnitude up to over 200,000 A.

4.15.4 SCREW-TIGHTENING DEVICES

Approved screw-tightening devices designed for the purpose of pressure metal-to-metal contact

are required for connections to an adequate system ground.

4.15.5 GROUNDING CABLE LENGTH

Grounding cables should be no longer than is necessary, both to minimize voltage drop and to

prevent violent movement under fault conditions. For example, as a general rule, grounding

cables should not exceed 30 feet for a transmission line and 40 feet for substation use.

4.15.6 GROUNDING CABLE CONNECTION

Grounding cables shall be connected between phases to the grounded structure and to the

system neutral to minimize the voltage drop across the work area if the circuit should become

inadvertently reenergized. Workers shall install the ground end clamp of a grounding cable first

and remove it last.

4.15.7 CONNECTING GROUNDING CABLES IN SEQUENCE

Grounding cables shall be connected to the ground bus, structure, or conductor first, then to the

individual phase conductors. The first connection of the grounding cables to the circuit phase

conductors shall be to the closest phase of the system and then to each succeeding phase in

the order of closeness.

4.15.8 REMOVING PROTECTIVE GROUNDS

When removing personnel protective grounds, reverse the order they were applied to the

phases. The grounding cable conductors attached to the ground bus, structure, or conductors

shall always be removed last.

4.15.9 PROTECTIVE APPAREL AND EQUIPMENT

Protective apparel shall be worn when applying or removing grounds. An insulating tool (hot

stick) shall be used to install and remove grounding cables.

Protective apparel (PPE) should include at least the following:

1. Safety glasses and, if necessary, a face shield appropriate for existing fault currents.

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