The first thing to say is that the test is quite clearly explained in the On Site Guide on page 82. It is important to remember that this test is done with the installation locked off. No power is required for this. Once the power is off, disconnect the ring main from the CCU. Once this is done, the line and cpc are cross connected, this usually done by connecting them into a connector block. This is slightly complex so please consult the OSG page 82 for a visual. When this is done then a low resistance ohm meter is connected between the line and cpc at each socket on the ring. The highest reading in ohms will represent the R1+R2 reading of the ring main circuit. Please consult the IEE regs before carrying this test.