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R1 + R2 at every point, and the highest readingFifty downlights. How many readings?
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With the link in, go to every point on the circuit: every luminaire, every switch, every socket, every outlet. At each one, one probe on the line terminal, one on the CPC terminal, press test.
Keep the highest reading in your head, or jot each one down. That highest reading is what you record as the circuit’s R1 + R2 on the schedule of test results.
- Expect low numbers on short runs. A short demonstration circuit can read a few hundredths of an ohm.
- Don’t be alarmed by an ohm or more on a long lighting circuit in 1 mm². Length and a small conductor both push resistance up.
- At a switch you are proving the CPC is there. One reading on a line conductor at the switch does it; the switch itself doesn’t need operating.
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- 18th Edition
- Building Regs
- PAT
- Fundamental Inspection & Testing
- Initial Verification
- Periodic Inspection & Testing