Question

At the intake position, the earthing conductor from the main earthing terminal is terminated to the combined neutral and earth (CNE) terminal of the service cut-out. This type of supply system is:

a) TN−C−S
b) TN−S
c) TN−C
d) IT 3)

Answer 1

The type of supply system described, where an earthing conductor is terminated to the CNE terminal of the service cut-out, is a TN-C-S system.

Step-by-step explanation:

The question pertains to the type of earthing system used in electrical supply, where the earthing conductor from the main earthing terminal is terminated to the combined neutral and earth (CNE) terminal of the service cut-out. This describes a TN-C-S supply system. In a TN-C-S system, the neutral and earth are combined in one conductor from the supply to the point of the service cut-out or distribution board, where they are then separated. The connection between the neutral wire and earth ensures that it is at zero volts, making it safe to touch and providing a return path for the current and, in case of a fault, a path through the earth to complete the circuit. The metal case of an appliance is also connected to earth, ensuring that it remains at zero potential and offers protection against electric shock.