The house was refurbished about 15 years ago
The electrical system is overkill - each room has it own circuit for power and lighting - each bathroom has a separate RCBO for UFH, heated towel rail and spa bath and an MCB for lighting.
The DNO was SSE
I was assuming the DNO owned the RCD but I could be wrong. I have a TT system at my own house but here the RCD is fitted between the main fuse and the meter so this would be DNO property.
They probably fitted the isolator as they didn't have a 4 pole RCD in the van -
but...
Many thanks for your quick replies
I believe it is a TT system as it is a rural property with overhead conductors. Also there is an earth spike connected to the earth connection going to the bottom LH corner.
I'm presuming this is hazardous as without knowing the earth impedance you cannot...
I've been doing some (non-electrical) odd jobs at a large country house nearby.
Recently, they had to call out the DNO as there was smoke and arcing sounds coming from inside the CU cupboard. The DNO cleared a slug from the RCD box - However, they have replaced the RCD with a isolation switch...