Puzzle:Service Tunnel Power Line
First, crouch and go under one of the transformers to avoid stepping in the electrified oil on the floor.
Turn off the two transformers on the 'main' side of the room. The lights should go out.
Turn on the two transformers on the 'aux' side of the room. If the lights turn on, you have done something incorrectly. Make sure the switch on the panel at the other side of the room is set to 'main'.
Walk over to the main control panel and switch the power from 'main' to 'aux'. The lights should come on.
Climb up the ladder and press the fan override button. The fan should turn on, and the broken cable should be blown free of the puddle.
After this, simply run down and turn the transformers on the main line on, then run back and switch the power back to main from aux. You can now leave through the door.