This adaptor allows the testing of mains extension leads. Plug the mains extension lead into the PAT-IT or the BattPAT. Plug the adaptor into one of the sockets of the extension lead and also into the IEC testing socket on the PAT-IT or the BattPAT. Press the IEC button (the Power Cord button on the battPAT) to test.
On any other PAT Tester which has an IEC lead test facility, follow the instructions in the user manual.
The IEC lead is kept short so that it's contribution to the Earth Continuity resistance is negligible.