Could anyone please tell me what the most common used form is? I mean, when suddenly all the electricity supply in home or an area is disconnected. When we say "Lights went off", does that just refer to the "Brightness form lights", or that even other electrical equipment don't work? Thanks a lot...
In my part of the US we usually say, "The power went out." However, saying the electricity/lights went off/out would be understood and not considered incorrect.
BrE (South East England), I'd say:
We've had a power cut.
There's been a power cut.
If someone told me that their lights were out/had gone out etc, I would assume it was literally just the main lighting (the ceiling lights) which weren't working. I would expect all other electrical items to be working. In the UK, the lights are usually on a separate switch in the fusebox, not necessarily on the ringmain, so it's possible for the lights to have a problem without anything else being affected.