Tails.

[Picker]

I'm rewiring my new (old) house...

Is there a maximum - permissible length for meter tails? And, being as the "existing" earthing connection to the meter bus (from the incoming mains) is taken from the metal reinforcement sheathing -

(which in the past had NEVER been connected into the house circuit AAAGH!)

I digress, - does this indicate that it's a TN-C-S setup? I can't see/find an earth rod, or other connection?

" To HELL with the O.D.P.M " !

Thanks in advance.

[usenet]

It's set by the "supply company" whoever they are nowadays, best of luck finding out. The typical maximum lengths are usually in the range of one to three metres I believe. If you want to make them longer then you need protection (e.g. a switch fuse) close to the company fuse.

If the "metal reinforcement sheathing" is in addition two conductors then it's indicative of TN-S. (The earth is 'S'eparate both in the supply and your house wiring)

Only if the "metal reinforcement sheathing" is also the neutral conductor (i.e. a single conductor only in the supply cable) does it indicate TN-C-S. (The earth is 'C'ommon in the supply but 'S'eparate in your house)

[Andy]

There was some disagreement on this NG as to what type of suppy I had when I mentioned it a while back. What was certain was that I had a 'concentric' cable, with multiple live conductors in the centre, then a sheath of multiple neutral conductors. The house earth was formed by taking about a third or so of the neutral conductors and peeling them off to an earth block I thought it was TN-C-S but there was some talk of PME and not really being able to tell1 I'd guess TN-C-S if I had to put money on it.

Andy.

[John Rumm]

TN-C-S and PME are just different terms for the same thing... (neutral and earth bonded at the head end of the consumers supply, rather than at the sub station)

[usenet]

TN-C-S and PME are two names for the same thing (well, maybe not quite, but for a domestic supply if it's TN-C-S then it's PME).

[Andrew Gabriel]

TN-C-S refers to the whole system, including supplier's local network and the subscriber's installation. In the UK, a TN-C-S system must be provided via a PME supplier's network. Regulations in other countries might not always require the supply network for a TN-C-S system to be multiply earthed in the PEN conductor (combined Protective Earth and Neutral in the supply network).

So the two aren't the same thing, but they go together in the UK. (Of course, you could have a PME supply network and a TT installation, if you choose not to use the supplier's earth.)

[Dave Plowman (News)]

At some time before I bought my house, the meter etc was moved from the cellar to the top of the (cellar) stairs. The LEB used 3 core SWA cable, using the yellow to extend the earth.