Live earth fault

[flinty]

Here is an odd one for you.
My brother plugged in his vacuum cleaner about a month ago to a downstairs socket and it tripped out.
The MCB didn't flick off but all the sockets stopped working.. About an hour later though they started again.
Then yesterday he plugged the cleaner into a different socket and the sockets stopped working again. This time though they have not come back on.
The mcb is still in the on position and have tested it and it says it's ok. I have also swapped it with another and the sockets are still not working.
I have plugged a 'socket and see' in and it says that the live and earth are reversed.
I have checked the two sockets that were used on the two occasions and they both have no loose wires or anything. I have also checked in the consumer unit and all the wires are tight with no signs of any problems.

any ideas?

Thanks in advance.

 

[TicklyT]

IIRC 'socket and see' type devices may indicate live and earth reversed if the neutral is disconnected or loose.

If it is similar to the devices I have seen, then it is checking the L, N & E, expecting to see two of the three (N & E) at about the same potential, and one conductor (Live) at a different potential.

If the Neutral is disconnected, anything left plugged into the non-working circuit may drag the neutral up to the same potential as the live, even if it isn't working.

The tester then sees two connections at about the same potential (in this case L & N) and one at a different potential (Earth) and cones to the erroneous conclusion that Live and earth are reversed.