Clamp Jaws - hdbk109220040124

DOE-HDBK-1092-2004

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

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

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

grounds, underground equipment grounding, and so on.

7.5.3.4.7.2

CLAMP JAWS

Bus clamps should be furnished with smooth jaws for installation on copper, aluminum, or

silverplated bus work without marring the surface. Conductor or metal structure clamps should

be furnished with serrations or cross-hatching designed to abrade or bite through corrosion

products on surfaces of the conductor or the metal structure being clamped. Several styles of

conductor and ground-end clamps have jaws that can be replaced when the serrations have

worn. Self-cleaning jaws are recommended for conductor-end clamps used on aluminum or

aluminum conductor steel reinforced (ACSR) conductors. Several styles of ground-end clamps

are designed with a cup-point set screw which should be tightened with a wrench (after the

serrated jaws have been securely tightened) to break through paint, rust, galvanized coating, or

corrosion on the surface that is to be clamped.

A typical grounding cable for transmission line work used by line crews consists of a 2/0 AWG

copper cable with an insulating jacket, terminated with an all-angle, self-cleaning aluminum

conductor clamp at one end, and a flat-faced clamp with a set screw at the other end for

connecting to a tower leg or ground wire/rod.

7.5.3.4.8

GROUNDING CLUSTER BARS

When climbing wood-pole structures, workers may use a grounding cluster bar to connect the

phase cables to the pole ground wire, if the ground wire has sufficient capacity to carry the fault

current. Cluster bars must have an attached bonding lead. If there is no pole ground wire, the

cluster bar for each pole is connected to a common driven or screw-in ground rod with a

grounding cable (or cables). In substation grounding, a copper bar is sometimes used to

connect the three-phase cables and a fourth cable to a riser from the station ground mat. When

installing personal grounds on wood structures from a bucket, the ground cables may be

connected between the overhead ground wire (OGW), and the phases without the use of cluster

bars provided that an electrical bond of sufficient current carrying capacity exists between the

OGW and the structure ground.

7.5.3.4.9

TEMPORARY GROUND RODS

Some typical examples of temporary ground rods used for grounding ungrounded structures or

mobile equipment, or during conductor splicing operations, are either:

1. A minimum ⅝-inch diameter bronze, copper, or copper-weld rod at least 6 feet long, driven

to a depth of at least 5 feet; or

2. A 6-foot, screw-type ground rod, consisting of a minimum ⅝-inch diameter copper-weld shaft

with a bronze auger bit and bronze T-handle, screwed to a depth of at least 5 feet

(preferred). The T-handle must be tightly connected to the rod.

If a temporary rod cannot be driven or screwed to a depth of 5 feet, additional rod(s) should be

driven or screwed so that a total of at least 5 feet of rod is buried. These rods shall be bonded

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