Ferrules

DOE-HDBK-1092-2004

inspection of the conductor for strand breakage, but becomes stiff and hard to handle at low

temperatures. The clear jacket will split or shatter at very low temperatures.

7.5.3.4.3

FERRULES

Ferrules should be threaded-stud copper base compression type. Ferrules should have the filler

compound vent hole at the bottom of the cable so that employees can visually check that the

cable is fully inserted into the ferrule. Compound should be used with crimped ferrules. The

ferrules should be crimped with the ferrule manufacturer's recommended die. The press shall

have enough pressure to completely close the die. The area covering the inserted cable jacket

should not be compressed. Heat shrink or springs should be installed over a portion of the

ferrule to minimize strand breakage caused by bending. In all cases, the manufacturer's

recommendations should be followed.

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:

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

installation with removable hot sticks.

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