The area you are calling the "electrical control center" is actually the entire bridge(just like in the movie) and it is NOT a seldomly used area. It is manned 24/7 by ballast control operators. The "motor control center" or MCC, that you are refering to as the electrical control center is inside the deck box of the rig.
Here's the basic deck layout of the rig. The Engine Control Room is where all of the breakers for the power generation can be found(what you are calling the (electrical controls unit). It is on the 2nd level in the deck box. The bridge is on the opposite side of the rig from the room you are referring to. If I can find the actual deck lay out drawings from the American Bureau of Shipping it will show you in extreme detail the location of everything aboard that rig. I'm sorry but your location labels are totally wrong.
http:// www.engineerlive.com/content/deep-trouble