Unfortunately it is not uncommon to see a permanent live (phase) taken from another circuit or indeed the same circuit pre isolator for timed overrun on boilers and fans etc
Just remembered one a few years ago. After a big freeze local community centre having a New Years Eve party for the oldies but the caretaker opened the door and water came gushing out, wood floors were cream crakered - thousands pounds of damage.
In the boiler room was a frost stat immediately above the boiler.
My guess was that it caled for heat, boiler fired, kept stat happy in the boiler room but meanwhile just above the stat the loft hatch was preventing much heat getting into loft to prevent pipes from freezing.
Ironic that just 2 metres of cable to site frost stat in loft would probably have saved the day.
Why did I mention this? because the perm phase did not isolate from the SFCU.
Just remembered one a few years ago. After a big freeze local community centre having a New Years Eve party for the oldies but the caretaker opened the door and water came gushing out, wood floors were cream crakered - thousands pounds of damage.
In the boiler room was a frost stat immediately above the boiler.
My guess was that it caled for heat, boiler fired, kept stat happy in the boiler room but meanwhile just above the stat the loft hatch was preventing much heat getting into loft to prevent pipes from freezing.
Ironic that just 2 metres of cable to site frost stat in loft would probably have saved the day.
Why did I mention this? because the perm phase did not isolate from the SFCU.
