The tests carried out by the LT7 Digital Loop Tester comply with International requirements for the testing of fixed wiring installations in industrial, commercial, and domestic premises. The resistance of the phase-neutral loop is needed to ensure that adequate over-current protection has been provided in the case of a short circuit developing between the two live conductors. The phase-earth loop resistance is also needed to ensure adequate over-current protection, but also to ensure that, in the case of an earth fault, an adequately large current will flow to activate any protective devices. These may be in the form of fuses or residual current devices.