Help with circuit finding

[lady electric]

Hi anyone shed any light on a problem i am having at the moment please
I am trying to find the reason why i cannot isolate a light in my mums garage,
it is a 3 storey house which used to be 3 flats and was rewired 30 years ago, i have found out there are 2 feeds still in the house
i have turned off what i thought to be the main isolater and removed all fuses (in 2 boards!!) i have searched high and low to find anyother boards to no avail
everything is off apart from this damn light (which is the only thing i need to work on!!)
the wire goes up and out of the garage and dissappears into no where, i cannot find anything in the vacinity that is linked - i have looked at switches and lights on all floors - albeit not everyone!!
How do i isolate the light?
Please help!!

 

[gaz101]

Have you tried switching off both diss boards then checking May
Possibly be fed from both boards

 

[Knobhead]

This reminds me of one I was told about on a EMEB training course. They went to disconnect the supply to a shop. Service fuse pulled and the power is still on. They had to dig the road up to find the tee in to the mains. Shop was owned by an ex cable jointer.

 

[BlueToBits]

I have seen a seperate DNO meter in a detached garage that never gets read. Or, It could be from a temporary builder's supply when the house was built and it was never removed.

 

[Knobhead]

I have seen a seperate DNO meter in a detached garage that never gets read. Or, It could be from a temporary builder's supply when the house was built and it was never removed.

Hoho, that sounds open to abuse J A decent sized feed to suposidly supply the garage would have to be soon layed.