The electric dynamos and the Orlop deck

 
The Orlop deck in this portion of the ship was refrigerated storage for everything from wine to flowers to bacon. A stores lift, or freight elevator, ran from the Orlop in the upper half of the drawing to the pantry in the 1st/2nd class galley on D-deck. The four big electric dynamos in this compartment provided the power for Titanic. The turbine engine is in the next compartment forward.

 
The four electric generators were steam powered. The 4 generators could produce 400kw each at a collective output of 16,000 amps at 100 volts. The simple version is that the Titanic could power a good-sized city. After the collision, it was necessary to keep enough boilers active to service the generators to keep the lights on as long as possible. H&W photo.

 
The switch room was the power control room and sat on the Orlop deck on the fore end of the generator room. Auxiliary generators sit on D-deck just aft of the turbine uptake in the event the generator compartment flooded in a collision, but the auxiliary generators could barely handle emergency lighting. H&W photo