What is the TN-C-S System?

What is the TN-C-S  System?

TN-C-S system

It has the supply neutral conductor of a distribution main connected with the earth at the source and at intervals along its run. This is usually referred to as protective multiple earthing (PME). With this arrangement, the distributor’s neutral conductor is also used to return earth fault currents arising in the consumer’s installation safely to the source. To achieve this, the distributor will provide a consumer’s earthing terminal, which is linked to the incoming neutral conductor.

TN-C-S system Advantages

• Reduces the number of conductors required for supply, which lowers the cost and complexity of wiring.

• Provides a low impedance path for fault currents, which ensures a fast operation of protective devices.

• Avoids any potential difference between neutral and earth within the consumer’s premises.

TN-C-S system Disadvantages

• There’s a risk of electric shock if the neutral conductor breaks between two earth points, increasing touch voltage on exposed metal parts.

• May cause unwanted currents to flow in metal pipes or structures that are connected to the earth at different points, which can result in corrosion or interference.