Handling of Grounding Cable

DOE-HDBK-1092-98

7.5.3.4.4 HANDLING OF GROUNDING CABLE

Personal protective grounds are usually handled and lifted by the cable. However, continuous flexing

eventually breaks the conductor strands beneath the jacket. Therefore, employees should minimize

the use of sharp bends in the cable.

7.5.3.4.5 SIZE OF GROUNDING CABLE

The size of the grounding cable must be selected to handle the maximum calculated fault current of

the power system or specific portion thereof. The minimum size that shall be used for grounding

cables is #2 (AWG) flexible copper. In larger substations, the maximum available fault current may

require larger cables. If larger cables are not available, parallel cables (with the appropriate derating

factor) may be used.

Most manufacturers and suppliers of grounding cables publish tables to assist the user in selecting

the proper cable size for a given fault current. These tables show the maximum fault current

capability for several sizes of copper grounding cables.

7.5.3.4.6 GROUNDING CABLE LENGTH

Excessive cable lengths should be avoided. Therefore, slack in the installed cables should be minimal

to reduce possible injury to workers. Resistance in the cable increases with cable length, and

excessive length could exceed the tolerable voltage drop across the body. Longer than necessary

cables also tend to twist or coil, which reduces the effectiveness of the cable.

7.5.3.4.7 GROUNDING CLAMPS

Grounding clamps are normally made of copper or aluminum alloys; sized to meet or exceed the

current-carrying capacity of the cable; and designed to provide a strong mechanical connection to

the conductor, metal structure, or ground wire/rod.

7.5.3.4.7.1 CLAMP TYPES

Clamps are furnished in, but not limited to, three types according to their function and methods of

installation:

1. Type I clamps, for installation on deenergized conductors, are equipped with eyes for

installation with removable hotsticks.

2. Type III clamps, for installation on permanently grounded conductor or metal structures, have

T-handles, eyes, and/or square-or hexagon-head screws.

3. Other types of special clamps are designed for specific applications, such as cluster grounds,

underground equipment grounding, and so on.

7-15