Head went funny.... Reverse polarity showed up and still after swapping cables ?

[LukeD]

Maybe lack of coffee etc ! Voltage also dropped to 140 for a bit . New ring . wired up correctly but indicated "reverse " . Could not be possible . Then tested other way and same thing ! Its a luxury apartment and only in there fitting longe plates. Building sparks arrived and fiddled in Consumer and it all came back to life. My remit did not allow me to open Consumer

 

[MJPD29]

What were your end to end/r1+r2 readings when testing?

 

[timhoward]

Is it on an RCBO?

 

[LukeD]

Is it on an RCBO?

Yes .. managed to find that out

 

[timhoward]

My best guess as follows:

Dead tests all passed fine.
Someone then manages to connect L+N backwards at consumer unit. More likely in an RCBO hence earlier question.
Circuit is energised for live tests.
Plug in and Zs test or RCD test will upset tester as Live to Earth is 0v and N to Earth is 230v. Most makes will show a warning lamp, or not light one of two orange lamps.
While removing either N or Earth some testers will show half supply voltage, maybe that explains that bit.

What I haven't worked out yet is your comment "tested other way and same happened". Did you swap two test leads over? If so was it definitely L and N you swapped?

 

[LukeD]

My best guess as follows:

Dead tests all passed fine.
Someone then manages to connect L+N backwards at consumer unit. More likely in an RCBO hence earlier question.
Circuit is energised for live tests.
Plug in and Zs test or RCD test will upset tester as Live to Earth is 0v and N to Earth is 230v. Most makes will show a warning lamp, or not light one of two orange lamps.
While removing either N or Earth some testers will show half supply voltage, maybe that explains that bit.

What I haven't worked out yet is your comment "tested other way and same happened". Did you swap two test leads over? If so was it definitely L and N you swapped?

THis would make sense. I was there only to fit some custom lounge plates . Was told not to touch CB etc by property manager as The client is still "buying" the property ! I swapped L & N and still got the initial error message