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Earthing metal conduitCan metal conduit be the CPC?
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This is one of the most important things about metal conduit. Because it's made of metal and contains live conductors, it's an exposed-conductive-part: a conductive part that isn't normally live but can become live under fault conditions. Nothing stops a damaged conductor touching the inside of the conduit and making the whole run live.
The whole metal conduit system must be connected to the MET (main earthing terminal), through a protective conductor, because it's an exposed-conductive-part.
- Some installers draw in only line and neutral and use the metal conduit itself as the CPC. That's allowed.
- If you do, then at initial verification (testing a new installation) you must verify the continuity from the MET all the way along the conduit, at the various points (boxes and entries).
BS 7671 · Section 543 · types of protective conductor (metal conduit is one allowed type)
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- Building Regs
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