Temporary Protective Grounding
Temporary Protective Grounding is the temporary installation of grounding conductors and clamps on de-energized electrical equipment or conductors so that if the circuit is accidentally re-energized, fault current is safely diverted and employees are protected from hazardous voltage differences. In Canadian practice, it aligns with WorkSafeBC's shock hazard control and federal regulations on temporary phase grounding.
In manufacturing or shop-floor settings, temporary protective grounding is used during maintenance, troubleshooting, or line work on de-energized feeders, switchgear, bus, cables, transformers, or distribution equipment when there is a credible possibility of induced voltage, backfeed, switching error, or accidental energization. The equipment must be selected and installed to carry the maximum fault current long enough for protective devices to operate, and placed to keep workers out of dangerous touch and step-potential zones. In Canadian utility-oriented procedures, it may also be used under approved work methods for rescue or when isolation points are inaccessible, with explicit control of hazardous step and touch potential.
- Wrong placement: grounds are installed in locations that do not actually prevent hazardous differences in electric potential, leaving the worker exposed to touch/step voltage.
- Undersized or poorly rated gear: cables, clamps, ferrules, or mats are not rated for the available fault current or clearing time, so the grounding set can overheat, fail, or delay protective device operation.
- Broken work process: the circuit is not properly tested as isolated before grounding, or the grounding is removed/installed without a controlled job plan, which conflicts with the core isolation and verification logic in Canadian and U.S. requirements.
Is temporary protective grounding the same as lockout/tagout?
No. Lockout/tagout is an energy-isolation administrative control; temporary protective grounding is a physical electrical protection measure applied after the circuit has been isolated and verified, to protect against accidental energization and induced or stored energy.
What is the key engineering requirement for a grounding set?
It must be able to conduct the maximum available fault current at the point of application for the time required for protective devices to clear the fault, without creating an unacceptable hazard.
What hazard do step and touch potential controls address?
They limit the voltage gradient around the grounded object and reduce the risk that a worker will receive a shock through their body when standing near or contacting grounded metal during a fault event.
When is a temporary ground considered acceptable in regulated work methods?
When it is part of a documented, employer-controlled procedure that identifies placement, sizing, application, and job-planning requirements, and when it is installed in a way that demonstrably prevents exposure to hazardous potential differences.
What Canadian language is most relevant if a site uses utility-style protection practices?
WorkSafeBC guidance on worker protection grounding/bonding, hazardous step and touch potential, and approved work methods is the most directly relevant Canadian source in the supplied material.