This makes me cross. I was a passenger on this flight and NO this was not standard light dimming. My uncle is a retired pilot who flew for more than 30 years and I know procedure.
The cabin lights went off, completely and we were left in the pitch black. Stewardesses went around the cabin staying there was a problem with the electrics, but not to panic. Landing in pitch black and being stuck in it inside the plane for nearly two hours was not fun.
What is worse is this fault occurred BEFORE the plane took off. As the plane taxied and the safety video had just started all the lights in the cabin went off as did the TVs. About 10 seconds later they came back on, we were told not to worry. The safety video was not re-shown.
We were later told this same plane had reported the same smell and been forced to perform the same emergency landing on Friday. The plane also dumped its fuel prior to returning, so there was clearly concern to get back as fast as possible.
The whole incident was handled extremely poorly. We were left on the plane for over two hours and there was no communication as to why. Water was eventually offered after more than an hour and many of the passengers were left badly shaken.