Principle

Common mode currents coming from outside must be discharged to the ground network at the entrance to the site in order to limit voltages between equipments.

NOTE: Any conducting lines (conducting cable, conducting pipework or insulating pipework carrying a conducting fluid), entering in a building must be connected to a ground at the entrance of the building and at the shortest possible distance.

Surge absorbers must be placed on electricity, telecommunications and signal cable (for data, alarms, access checks, video supervision,….) at the entrance to the buildings. The effeciency of such devices is largely influenced by the way they are installed.

The surge absorbers (varistors, discharge gaps etc.) must be connected directly to the ground connection on the electrical panel or to equipments they are protecting. Simply connecting surge absorbers to earth (instead of the mechanical ground) is not effecient.

As far as possible the panels, where the electrical, telecommunications and signal protectors are installed, must be placed close to a grounding strip.