What is the minimum size for the main conductor bonding in a TN-C-S system?

The minimum size for the main conductor bonding in a TN-C-S system is indeed 10 mm². This specification is critical because the bonding conductor plays an essential role in ensuring safety by connecting the exposed conductive parts of an installation to the electrical system's neutral point. It allows for proper fault current paths and helps maintain the voltage levels between the earth and all exposed conductive parts during fault conditions.

In a TN-C-S system, which utilizes both the neutral and protective earth conductors, the bonding conductor must be adequately sized to handle potential fault currents safely. The 10 mm² size conforms to the relevant electrical standards and regulations, ensuring effective operation and minimizing the risk of overheating or damage to the conductors during normal operation and under fault conditions.

Selecting a bonding conductor that's too small could compromise the safety and reliability of the installation, while larger sizes may be unnecessary and ineffective in addressing the specific requirements of the system. Thus, the 10 mm² size is both a regulatory requirement and a practical solution for maintaining safety standards in TN-C-S systems.