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Topic Title: Twin & Earth to CU
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Created On: 20 October 2017 01:19 PM
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 09 November 2017 01:17 PM
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geoffsd

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Joined: 15 June 2010

The OP is about his house.
 09 November 2017 01:27 PM
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AJJewsbury

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It is in the definitions.

Likewise protective conductors (e.g.. c.p.c.s) - and conductors for functional earthing (e.g. the white wire from RCBOs) but they typically don't go directly to the earth block when it's deemed to be the MET. They are connected, just not directly. If that arrangement is acceptable for other connections why not for main bonding?

Are we agreed that there can be only one MET and one Earthing Conductor?

Humm, can I think about that? Usually we'd call the earth terminal in outbuildings etc a building earth marshalling terminal or some such to distinguish it from the overall MET (of which there should be exactly one per installation (at least where ADS is used) - but I'm not sure that BS 7671 itself takes that approach - just asking for the overall arrangement of MET and main bonding to be repeated for each building (or at least that's my reading of it).

- Andy.
 09 November 2017 01:37 PM
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geoffsd

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Originally posted by: AJJewsbury

Likewise protective conductors (e.g.. c.p.c.s) - and conductors for functional earthing (e.g. the white wire from RCBOs) but they typically don't go directly to the earth block when it's deemed to be the MET. They are connected, just not directly. If that arrangement is acceptable for other connections why not for main bonding?

Yes indeed, no way around that.

That would tend to suggest the MET has to be in the CU - but there is no reason why it should be.

Just inconsistent regulations again?
 09 November 2017 01:38 PM
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geoffsd

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As for thinking about it - there can, by definition, only be one MAIN earthing terminal.
 09 November 2017 07:04 PM
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AJJewsbury

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Just inconsistent regulations again?

Well certainly not as transparent as it might be!
- Andy.
IET » Wiring and the regulations » Twin & Earth to CU

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