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Electric Power >> Hazardous Energy Control >>
Portable Grounding Equipment
Hazardous Energy Control
Portable Grounding Equipment
Portable grounding cables and clamps must be able to carry and withstand the
maximum fault current available for the time needed for an overcurrent device to
trip. The amount of available fault current needs to be determined; depending on
the amount, two or more leads in parallel may need to be installed. See 1910.269(n)(4).
Each grounding cable installed on transmission and primary voltage distribution
systems must be at least a #2 copper (or equivalent).
On secondary voltage systems (600 volts and less), ground leads must be sized so
that they are larger than the conductor and have an impedance low enough so that
the operation of any protective device is not delayed. For guidance, see CPL
02-01-038, Appendix B, Item 11.
Clamps and Cables
The clamps on ground leads are a critical component and are much larger than
common distribution connectors (such as hotline clamps or bolted connectors) due
to the large amount of current that needs to be carried. Some critical factors
to consider are:
- The shape of the clamp must be compatible with the shape of the conductor to
get the most contact surface and lowest resistance (for example, a clamp
designed for use on a round conductor should not be used on a flat bus bar).
This will also help keep the connection in place when heavy fault current flows.
- Cables should be as short as possible to reduce "whipping" when fault current
is carried and to reduce the weight of the leads. Whipping can result in
sufficient force to dislodge or damage the cables or clamps if the circuit
becomes energized. If short cables are not available, then the cables should be
tied or lashed securely.

- The connection between the ground cable and the clamps on either end should be
inspected periodically to ensure they are in good condition. The cable should be
inspected for damage and defects.
- Protective grounds are only as effective as their proper installation,
including clean connection points, tight connections, and adequate cable and
clamp size and rating.
Equipotential
Zone
Grounding for Employee Protection
Protective Grounding and Bonding
Insulating Protective Equipment (IPE)
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