ABSTRACT
The correct operation of the ADS system is verified by the successful completion of a range of tests, for example the earth fault loop impedance tests. In the UK, the supply provided to the electrical installation generally falls into one of three types; these types are differentiated by the method of supplying a connection to the general mass of earth and therefore are commonly referred to as earthing systems. The three systems are named TN-S, TN-C-S and TT, and the names help to describe how earthing is achieved within the system. TN-S systems are perhaps the most straightforward to understand because, like most circuits, they use separate conductors for neutral and protective earth. TN-C-S earthing system is the most common type of system used in the UK and is an improvement over the TN-S system because it does not use separate neutral and protective conductors in the supply.
