As to the floor casing of the TOS Engine room being the energizer, I would suggest that it is more the top of large energizer machinery that is below the floor. Kinda like how in TWOK that the crystals are on top of a shaft that leads down below to what I would imagine to be the energizers.
I would like to believe that this
is what this actually would look like.
The "primary EPS relay" column seems to match rather good one of the top circular elements of the TOS energizer
Please disregard the centered EPS relay in my last draft for Engineering Deck 12