The door of this cabinet was wide open as I passed it on East Bridge Street. I took these photos and closed the door gently with my toe, but when I passed it again later someone had opened it again. Odd.
The Merlin Gerin Isobar 4 is a module electrical distribution board system for general use. Unfortunately at the time I hadn't spotted the meter tucked away in at the left or I would have snapped a photo of it, too.
I would guess that this handles the electrical load for the seemingly-pointless uplights on the footbridge leading to the Hilton.