Main earthing bar or loop is to be conveniently located in electrical/mechanical plant rooms, and connected by earthing conductors to exposed conductive parts of motor control centre at its earthing bar, and to motors, switches and other electrical equipment etc. at their earthing terminals, using 20 x 2 mm insulated copper strips or 35 mm2 insulated copper conductor (minimum size) or as required to carry maximum earth fault current for 1 second with final conductor temperature not exceeding 200 deg. C (392 deg. F).
Conductors are to be securely fixed, recessed in floor grooves or niches, or fixed to walls by appropriate staples. Earth bar or loop is to be securely fixed to building wall with copper or brass saddles.
Main earthing bar or loop is to be connected at 2 extremely separate points to earth electrode, directly through 2 test joints by insulated earthing conductors, or connected to main earth bar by protective conductors.
Motor and other equipment earth terminals are to be connected also by protective earth conductors of each branch circuit to earth terminal / bar at motor control centre, panel or distribution unit.