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Ring final practical, step 2: figure of eight, line to neutralWhy divide by four?

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Join the line of one leg to the neutral of the other, and the other line to the other neutral. Opposite ends — that cross-connection is the figure of eight. Then test between line and neutral at every socket on the ring, with a plug-in adapter and the socket switched on.

At the board L of leg A + N of leg B L of leg B + N of leg A every socket: L to N two parallel halves of the loop expect (r₁ + rₙ) ÷ 4 · the same at every socket
Cross-connected, the loop splits into two parallel halves, each half of r1 + rn, so the reading is a quarter of r1 + rn — and it should be the same at every socket.
  • Switch the socket off first and press test: open circuit. On: a reading. That proves the switch, too.
  • A spur reads a little higher than the ring sockets — it’s extra cable.
  • A fused connection unit with no socket: take the plate off and probe the supply-side line and neutral terminals.
Is the cross-connection right? If the readings rise towards the middle of the ring and fall again towards the other end, you’ve joined line and neutral of the same leg, not opposite legs. On twin and earth you can see which belong together; on singles in conduit you can’t, so mark the legs.

Step 2 isn’t recorded — there’s no column for it. That doesn’t make it optional. It’s a step towards proving polarity, and it finds faults nothing else will (section 5).

Guidance Note 3 · 2.6.6 step 2

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