Saw IV (2007)

Visible crew/equipment: Several times in the movie you can see a stunt double for Donnie Wahlberg, like when he tries to hang himself. Art runs over and there is a wide shot focusing on both of them. No slo-mo required, but you can see it's a stunt double.

Eric Mathews: I don't want to play anymore.

Trivia: The footage in the beginning of the movie that shows Jigsaw swallowing the wax-covered cassette was actually shot during production of "Saw III", but was not used in the final cut.

Question: I don't understand why Hoffman isn't electrocuted at the end. He was connected to high voltage cages and his feet came under water, so how did he and/or Jigsaw plan so he wouldn't be electrocuted under any circumstances?