The cell.

[Ruhiel]

Well, even though that was the easy way, what about this one:

You pull the light down from the ceiling. Being as careful as possible, you break off the glass surrounding the bulb, so that the steel wool inside isn't harmed. Then, pull the lamp down, and press the electrified steel wool to the door. If that lightbulb was actually on, the door should catch fire within an hour or so, unless it was wet... then u screwed.

<.<
>.>
I just wanted to put that anyways...