To check site supply for polarity reversal etc., simply plug the W4 Mains Tester in to trailing socket and then connect blue plug to site outlet, then look at the tester display.
The W4 Mains testing kit comprises of
- Mains Tester - To check internal socket connections
- Trailing Socket - When connected to a European standard site socket, appliances fitted with a 13A 3-pin plug can be used