- Reaction score
- 3,011
R1 + R2 is a multi layered test, the only true value is done on design. as a designer you will design a circuit and to ensure several pieces of criteria you do a calculated R1+R2 to confirm the cable.
On an EIC say a rewire, most electricians will before they start connecting up the CU, do IR tests and also the R1+R2 test, this should give you a very good indication of condition as the R1 + R2 should be very close to a calulated one. But of course you may think you have installed 25mteres of cable, but in fact you have installed 31 metres, so the measured and the calculated one will be close but never the same. You also have to take into account quality of conductor and if doing it via a socket then even that.
On a PIR then I'm afraid your in the lap of the gods. it can depend on so many factors. You may not be able to disconnect the supply so you only do a R2 test. The earths in the CU are not sequencial and so you have to clip the bar as you did in your test, and then you get those parallel paths, but that is what you put on your schedule of Results. In many cases you will not have diagrams. let alone design charts to compare so you just have to guestimate a lot.
On an EIC say a rewire, most electricians will before they start connecting up the CU, do IR tests and also the R1+R2 test, this should give you a very good indication of condition as the R1 + R2 should be very close to a calulated one. But of course you may think you have installed 25mteres of cable, but in fact you have installed 31 metres, so the measured and the calculated one will be close but never the same. You also have to take into account quality of conductor and if doing it via a socket then even that.
On a PIR then I'm afraid your in the lap of the gods. it can depend on so many factors. You may not be able to disconnect the supply so you only do a R2 test. The earths in the CU are not sequencial and so you have to clip the bar as you did in your test, and then you get those parallel paths, but that is what you put on your schedule of Results. In many cases you will not have diagrams. let alone design charts to compare so you just have to guestimate a lot.