Ive seen many dangerous things at abandoned buildings and in public.
IM IN THE TRADES I HOLD AN ELECTRICAL LICENSE IVE DONE PLUMBING ,NATURAL GAS PIPING, PROPANE PIPING [MAJOR INSTALLS].
Ive entered abandoned houses WITH ALL THE DOORS WIDE OPENED and found working lights [electricity] NATURAL GAS range WITH WORKING PILOTS AND FULLY FUNCTIONAL.
I will first go to the electrical main service entrance panel and FLIP ALL BREAKERS INCLUDING ALL MAINS [FUSE BOX] I WILL PULL OUT THE MAIN FUSE BLOCKS OR THROW TO OFF MAIN SAFETY SWITCH AND LOOSEN ALL SCREW IN FUSES.[this is so some one doesnt get hurt or do some thing stupid]
NATURAL GAS GO TO THE METER AND GIVE THE VALVE 1/4 TURN you will need a wrench,
PROPANE LP GAS GO TO THE TANK, TANKS AND TURN OFF ALL THE VALVES LOCATED ON THE TOP OF THE TANK TANKS SOME TIMES UNDER THE BONNET. [i do this because kids will put stuff on top of the range top and burn the place down]
WATER turn off main by water meter if so equipped.
GATE AND GLOBE VALVE ROTATE HANDWHEEL CLOCKWISE UNTIL IT STOPS TIGHT,
BALL VALVE ROTATE HANDLE 1/4 TURN.

Ive seen open manholes out in public with no one in site I PUT THEM BACK ON.
HATCHES ,crawl space scuttles ect I PUT THOSE BACK ON if i see this [ABANDONED BUILDINGS].

I was on a job for my employer and was in the crawl space THE OLD LADY WALKED INTO THE ROOM FELL 4 FEET into the SCUTTLE HOLE we had to call an AMBULANCE IT COST THE INSURANCE COMPANY 60'000'00 [SIXTY THOUSAND DOLLARS]I felt really bad.[1980S]

If your out exploring and find these things TAKE CONTROL!! AT LEAST PUT BACK COVERS ON THE FLOOR SO NO ONE ELSE GET HURT.

Welcome back old timer
Doubt if many will see it here... throw it on the hellhole thread:
http://www.uer.ca/...=1&threadid=122644

I would cover a manhole if the cover is there or mark it.
Found an open one walking through tall grass at Pennhurst... the easy way.
Spooky stuff.

As for water and electric I probably leave alone; no touch, no liability plus it's not my property to play with.
It may be active for a reason.