TN-C-S with earthing through the sheath??

2 Jul 2004
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United Kingdom
Has anyone ever come across a TN-C-S installation where the main earthing connection is to the service main sheath before the cutout.

The installation looks like a classic TN-S arrangement and I would have assumed it was TN-S if it had not been for discovering a 15th ed. installation certificate from the REC behind the meter. It indicated TN-C-S with the word SHEATH in the comments box.
I've contacted the REC for clarification but in the meantime I though I'd ask the forum.

Has anyone seen this before - or is the cert wrong. (I'm sure the certificate relates to the installation I'm seeing. There is no earth from the neutral side of the cutout. I'd guess the cutout/cable predates the meter/installation).

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All I can say is a job I worked on in Bristol was "converted" to PME by the engineer who connected an earth supply from the neutral, so I suppose your installation is similar.

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