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Ring final circuits, step 3: line to CPC, and the one you recordWhich ring reading goes on the certificate?

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Same idea, different pair. Undo the neutrals, leave the lines alone, and cross-connect line with CPC the other way round.

8Figure of eight between line and CPC. This is your R1 + R2, and this is the one that goes on the certificate.

Expected R1 + R2

Expected = (r1 + r2) ÷ 4

(0.01 + 0.02) ÷ 4 = 0.0075 Ω, so about 0.01 Ω
Measured at the sockets: about 0.01 Ω at each one (record the highest reading)
0.00 on the display still gets written as 0.01. You cannot record a zero.
✋Don't forget to move your test leads. The classic mistake: you change the links over in the consumer unit, walk back to the socket, and test without moving the leads. Then you spend ten minutes wondering about the results.

If you've done R1 + R2, do you still need an R2?

✓No. On a ring, step 1 already measured r2 end to end, and the certificate's wording gives you "or". You've tested the CPC twice — once on its own in step 1, once as part of the figure of eight in step 3.
So when would you use an R2 test on its own? Where there's no line conductor involved — your main protective bonding out to the gas and water, and supplementary bonding. Those are tested on their own, and on the schedule they get a tick for continuity verified, not a number.

GN3 · 2.6.6 · p.63 · ring final continuity, step 3 ★

consumer unit L of one leg to cpc of the other cpc R₁ + R₂ = (r₁ + r₂) ÷ 4 (0.01 + 0.02) ÷ 4 ≈ 0.01 Ω this is the one you record ✋ Move your test leads after changing the links. Testing with the leads still where they were is the classic mistake.
Same cross-connection, different pair. Record the highest reading from around the ring — and a display reading of 0.00 still gets written down as 0.01.

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