When the power goes off the computer screen is still on and the lights on the board are still lit in the recording booth.
They are in the station and DS Florence Cassell is wearing a black number, and it is suggested that they to go through the magazines at Catherine's bar. By the time they get there, Florence is wearing red shorts. Did she really need to go and change?
If power was lost in the studio when the lighting system was dropped in the pool, there should not have been any concern about the pool being live, therefore getting the body out of the pool would not have caused an electric shock.