The Megger MST220 Socket Tester is a plug-in style tester that uses both a visual and audible indication to provide quick and easy indication of possible wiring errors which may be present at UK BS1363 13 A 3-pin power sockets. Over 17 combinations of wiring fault can be identified including missing wires and incorrect or reversed connections. Correct wiring configuration is indicated by 3 bright green LEDs and a continuous tone. A combination of green, red and amber LEDs with a warble tone indicates a wiring fault which requires further investigation. Reference to the included table will indicate the particular wiring fault present. The MST220 can be used for initial identification of socket faults following socket replacement or re-wire work of any kind. Simple miss-wires or missing connections can be quickly identified prior to full BS7671 electrical inspection and test, so saving time during the testing and certification process. The MST220 may also be used during installation or commissioning of electrical equipment connected to 13 A sockets such as white goods if a wiring fault is suspected. Please Note The MST220 will not detect neutral - earth reversal