Equipotential Grounding Procedures Protective Grounding Training

Purpose of Grounding Electrostatic Induction Electromagnetic Induction De-energizing and grounding electrical lines/equipment represents the best possible protection for high-voltage line workers. If it isn’t grounded, it isn’t dead! Some of the dangers you face: Electrostatic Induction Electromagnetic Induction Accidental Closing Accidental Contact Equipment Failure Backfeed

Requirements of a Protective Ground For proper protection, protective grounds must fulfill the following requirements: Low Resistance Inspection and Testing Connection at Proper Points Provide for a Minimum Potential Difference Across the Worker Movement of Protective Grounding Cables

Applying Grounds Properly All grounding clamps should be placed on primary conductors using an approved ‘hot stick’ Use only approved grounding cables and clamps The conductor must be tested for ‘dead’ with an approved and properly functioning tester If voltage is detected, stop work immediately until the line/equipment is de-energized and retested Clean the attachment surfaces before connecting grounding clamps When grounding de-energized equipment, connect cable to ‘ground’ before approaching a conductor that is to be grounded Continued

Applying Grounds Properly, Con’t No grounding connection should be placed such as to interfere with work to be done. Stow cables carefully. Do not coil cables Workers should avoid standing near earth grounded points because of danger due to ‘step-touch’ potential Avoid installing protective grounds in series with a fuse or switch. A Supervisor should approve this procedure if it is found to be necessary Grounding cables used should be sized to carry the anticipated fault current

Grounding Overhead Lines On Metal Structures: The structure itself must be grounded and all protective grounds should be connected to the structure On Wooden Structures: All protective grounds should be attached to a grounding ‘cluster’ immediately below the feet of the workers. This grounding cluster should be anchored deeply into the wooden pole to ensure an adequate path to ground

Grounding Underground Circuits Underground circuits represent an additional hazard to the worker. Additional precautions are required and only workers qualified to work on underground systems should perform such work. All conductors of the circuit to be worked on should be opened and grounded at the closest opening points Before grounding the circuit, test the conductors using the same precautions as with O/H lines Before cutting into an assumed ‘dead’ underground primary cable, pierce the cable from a remote location to test for ‘dead’ once again (spiking clamp w/ hot stick or remotely actuated hydraulic cutting tool are typical methods) Follow Company practices concerning protective insulation and grounding of URD systems (contact Safety Manager for questions)

Typical Example Wooden Pole Equipotential Grounding Scheme Key Description 1. Ground Clamp 2. Two Ferrules Applied 3. Cluster Bar 4. Screw Ground Rod 5. #2 Clear Jacket Cable 6. Parking Stand Optional

Protective Grounding Training © Copyright by the Institute for Safety in Powerline Construction 5501-A John Eskew Blvd. Alexandria, LA 71303 866-880-1380 All rights reserved. This material or any part thereof may not be reproduced in any form without the written permission of the Institute for Safety in Powerline Construction