R1 & R2 on light circuit

[andyww]

Following an install we carried out in February that tested fine when complete, we have returned (finally) to commission the installation and on retesting are getting a strange reading on a light circuit: (bearing in mind, in the intervening 6 months, builders have been in and refurbed the flat)On a new lighting circuit, R1 & R2 test produces this result: with the light switch on reading is 0.18, with the light switch off it still reads 0.78
Switching is in a JB and to my mind with the switch off it should show open circuit - but we are getting continuity at 0.78

Anyone got any suggestions?

 

[FaradaysHaircut]

Following an install we carried out in February that tested fine when complete, we have returned (finally) to commission the installation and on retesting are getting a strange reading on a light circuit: (bearing in mind, in the intervening 6 months, builders have been in and refurbed the flat)On a new lighting circuit, R1 & R2 test produces this result: with the light switch on reading is 0.18, with the light switch off it still reads 0.78
Switching is in a JB and to my mind with the switch off it should show open circuit - but we are getting continuity at 0.78

Anyone got any suggestions?

Check the wiring between the switch and the light. I seems that there may be a short circuit in this section perhaps caused during the building work. Also, check the switch wiring.

 

[Festerfly]

Check the wiring between the switch and the light. I seems that there may be a short circuit in this section perhaps caused during the building work. Also, check the switch wiring.

Agreed

 

[Sintra]

Following an install we carried out in February that tested fine when complete, we have returned (finally) to commission the installation and on retesting are getting a strange reading on a light circuit: (bearing in mind, in the intervening 6 months, builders have been in and refurbed the flat)On a new lighting circuit, R1 & R2 test produces this result: with the light switch on reading is 0.18, with the light switch off it still reads 0.78
Switching is in a JB and to my mind with the switch off it should show open circuit - but we are getting continuity at 0.78

Anyone got any suggestions?

Remove all lamps and transformers if fitted. Remove any links installed for testing and perform a 500V IR test between all conductors with switch off then perform again with switch on. This should determine whether or not you have a fault in you cable.

 

[diditrain]

Incorrect polarity in a J/B seen it many times

 

[andyww]

Thanks all - it was actually a screw through the plasterboard straight into a cable - Thanks builders!