R1+R2 Calculation

[stevechilts]

Carrying out a PIR on a Auto Garage the ring main is wired in metalic conduit with no earth cables what is the calculation to acheive R1+R2

 

[IQ Electrical]

You can't calculate it, you can prove continuity via earth loop impedance tests at each outlet and an R2 test if you feel it neccessary.

Each outlet must have a fly lead linking it to the metal back box regardless of fixed lugs.

 

[stevechilts]

Thanks for that, already done the earth loop test and flagged up no fly leads on sockets.