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The ring final circuit in three steps, and spursDoes the ring test cover a spur?

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The question at the end: Does the ring test cover a spur? The answer is in the notes below.

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The ring final circuit, in three steps

Still continuity, still a low-resistance ohmmeter. Step 1 happens at the board; steps 2 and 3 happen at every outlet.

StepWhatWhereFinds
1End to end on each conductor separately — r1, rn, r2At the board, legs disconnectedA break in the ring
2R1+Rn — cross-connect line and neutral, figure of eightEvery outletContinuity and high-resistance joints
3R1+R2 — cross-connect line and CPC, figure of eightEvery outletLine–neutral reversal, and the figure for the schedule
1 End to end, at the board legs disconnected — each conductor on its own board Ω r₁ Ω rₙ Ω r₂ one conductor at a time finds A break in the ring 2 R₁+Rₙ — line and neutral cross-connected at the board, figure of eight board Ω at every outlet finds Continuity, and high-resistance joints 3 R₁+R₂ — line and cpc the same again, and the one that matters board Ω at every outlet finds A reversed socket — and the figure for the schedule lineneutralcpc
Step 1 happens once, at the board, and only proves the ring is a ring. Steps 2 and 3 happen at every outlet — cross-connecting the pair is what makes the reading stay flat all the way round, so anything standing out is a joint. Step 3 is the one that catches a reversed socket, and it is the figure that goes on the schedule.
✋When you swap the pairs at the board, swap the leads at the adapter too. Forgetting is the single most common slip in ring testing — the reading comes back open circuit and the fault is in your hands, not the circuit.

Spurs and fused connection units

Step 1 only sees the ring itself. A spur is a dead end hanging off it, so end-to-end testing never registers it.

Every outlet on the ring gets tested at steps 2 and 3 — and a fused connection unit is an outlet

Plug-in adapters do the sockets. An FCU needs the faceplate dropping and the probes putting directly on the conductors — or the conductors moving temporarily into a connector block. Do not skip past it.

A spur reads high, and should. It is further from the board than the ring is at that point, so expect it.

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