these are amazing old things, huge cast iron enclosures, thick glass windows, gasketed up, 4 foot single T12 40 watt tube within

Interesting old fittings looks like it would take a man a hour to get in to one lol. What lamps were in them modern or vantage?

looked like 1970's standard Philips tubes, maybe 80's. Recon these worked till not that long back, within the last 15 years anyway

Wonder how easy they would be to open for maintenance?

undo a lot of bolts !

We had 2 pits at work like this, they filled them in with stone!, but I do remember some sort of weather packs down there?

Amazing! Nice and protected!