Commonly asked questions and answers regarding Electrical Safety Grounds or Temporary Protective Grounds.
When do I use temporary (safety) grounds?
Temporary protective grounds sometimes are called safety grounds. Because the purpose of the temporary ground is to limit the voltage between adjacent points, the ground should be used whenever a chance exists that the deenergized conductor could become reenergized. For instance, any conductor that is outside a building is subject to re-energization by a lightning discharge.
Why must temporary (safety) grounds be approved?
When current flows in an interaction of magnetic forces results in physical force being applied to the conductor. When the amount of current is on the order of available fault current, the physical force on the conductor is significant. Temporary ground sets must be rated by the manufacturer and approved to handle the available fault current. The approval process enables the user to determine whether the temporary ground will meet the needs of the specific task or situation.
What constitutes approval of temporary (safety) grounds?
In general, manufacturers test and rate ground sets. No third-party approval is required. Workers should use only purchased ground sets (temporary or safety grounds). If the manufacturer rates the ground set, it is approved for applications that do not exceed the rating.