Hi Evans,
No, I didn't realize this is a UK forum but all the advices I have received so far are great and helpful. I will keep in mind that there might be differences between our system. Here are answers to your questions:
1. This porch light does not have a switch. It is an outlet I had the builder put in as an extra.
2. I think this outlet is on the night time sensor circuit because the light worked before (on at night and off at daytime) and then it just went black. I test this bad outlet with the sensor circuit activated (i.e., I covered the photocell and the other two lights on this circuit were on) and there is no power at this bad outlet.
3. No electrical works were done in my house before this outlet went bad. It just stopped working.
4. My tester functions ok because I used it to test another outlet to verify.
No, Johnny Cash lived in Nashville, Tennessee. Henderson, NV (Lake Las Vegas) is where Celine Dion lives. In fact, she lives in the same development as I but she has a much bigger and better mansion...