What is the maximum disconnection time for a TT system for circuits not exceeding 32A?

In a TT system, which is characterized by having the neutral and earth conductors separated and relying on a local earth electrode, the maximum disconnection time is crucial for ensuring safety against electric shock. The regulations state that for final circuits with a rating not exceeding 32A, the maximum disconnection time is designed to ensure that under fault conditions, the electrical supply is interrupted quickly enough to minimize the risk of harm to individuals.

Setting the maximum disconnection time at 0.2 seconds is based on the specific needs for safety in environments where people may come into contact with electrical appliances. In the event of a fault that causes a dangerous situation, the disconnection timing is critical – ideally minimizing the duration of potential exposure to fault current.

This short disconnection time ensures that the circuit protective devices operate effectively, allowing for rapid isolation of the supply in the event of an electrical fault. The 0.2 seconds threshold aligns with industry standards aimed at protecting users from electric shock, especially in circuits powering equipment that could be reasonably expected to be used by people, such as in residential and commercial settings.

Therefore, the determination of the maximum disconnection time for a TT system for circuits not exceeding 32A as 0.2 seconds is both