On 14/02/2020 15:49, Tufnell Park wrote:
On 14/02/2020 11:23, TimW wrote:

This is the supply in the porch:
https://photos.app.goo.gl/ZhguWVyk5kZkbs1X9
Two substantial earth cables from the black box, one going to the box
of trip switches, the other just dangling, redundant from the old
economy 7 circuit or something.

Can wiser eyes than mine declare the type of earthing arrangement?

RW

It is not possible from the photo posted to say definitively what type
of earthing system you have here.

You would need to get a competent electrician to determine that.

I would say if Tim can confirm the presence of the PME sticker (assuming
this is a UK installation) on the left of the cutout, there is a very
strong likelihood of it being TN-C-S.

To be certain he could, turn off the power, pull the main fuse, and take
the cover off the cutout (with the normal warnings about access to live
parts etc). A TN-C-S install would have a metal bridge between the
neutral and earth terminal blocks in the cutout:

http://wiki.diyfaq.org.uk/index.php/...ePMECutout.jpg

The same style of cutout can be used for other supply types. Say it were
TN-S you may see something like:

http://wiki.diyfaq.org.uk/index.php/...PMECutout3.jpg

(Note the missing link, and the separate earth feed from a split
concentric cable)

You may be able to speak to your DNO (distribution network operator) to
determine if their network in your area has PME (protective multiple
earting) available.

Yup, they should be able to tell you what its capable off even if not
what your actual installation is.

Re Your original question about the 'earth wire' connected to the water
pipe, this is most likely to be a bonding connection.

I would concur.


--
Cheers,

John.

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