MCBS not turning off the right thing
Hi all so I was changing a bathroom wall fan heater from a 13 amp fused spur and thought for extra safety il turn off the ground floor power via the mcb for extra safety (fuse was already out of the fused spur) after doing this all power downstairs was still on so I decided to turn off each of the mcbs to check if they will turn off what they should.
I found the following -
*Fuse box - First floor on but ground floor off
= power to downstairs and upstairs
*Fuse box - ground floor on first floor off
= power downstairs and upstairs
*Fusebox - first floor off and ground floor off
= no power upstairs or downstairs
So upstairs power only turns off when both ground and first floor mcb is off.
Downstairs only turns off when upstairs mcb is off but can be turned back on by either mcb, ground or first floor
what could be causing this and how bad is this?