Potential balancing

Main potential balancing must be done in every building. Purpose of the main potential balancing is to prevent dangerous simultaneous voltage differences between reachable conducting parts. In potential balancing disposed to voltage and other conducting parts are connected to the same potential, when there are no equipotential differences. Usually, metal pipelines (heating, plumbing, ventilation), metal constructions and, when applicable, main reinforcing steels used in concrete constructions, are usually connected to the main potential balancing.

Potential balancing of cable trunking system

Protective earthing or connection to potential balancing conductor are usually not required for cable trunking system if shielded cables are being used. Exceptions are, for instance, hospital premises or explosion dangerous (Atex) premises. Also, in some individual cases, protective earthening or potential balancing of metal parts can be required, for instance, in order to avoid electric disturbance.

Additional and more detailed information about earthening of INSTAL cable trunkings you will find in the installation instruction through the following link (pdf).

Potential balancing of cable ladders and trays

Cable ladder, cable trays and lightning tracks can be regarded as disposed to voltage current conducting parts which shall be connected to the main potential balancing conductor at least at one point.

Especially in industrial installations special attention shall be paid to eathening of the whole cable ladder system, as well as to its reliability. At industrial sites it is recommended to connect cable trays, for instance, in every 40 m if it has not been fastened to a conducting construction in a realiable manner (for instance to an earthened steel column).

Extension joints SSR and SSU, used with cable ladders KS20 and KS80, give a sufficient electric connection, so there is no need to install a separate earthening conductor over the joint. Research statement of SFS Fimko can be found through the following link.

Electric conductivity of cable ladders and trays

Information about conductivity of cable/tray ladders and lightning tracks is presented below.