Old meters, meter tails and earth?

[MrS]

If there is an old meter in a house with 16mm tails from the supply and also from the meter, can a rewire be done as it is, or does the electricity board have to come out first and change both the supply and meter tails to 25mm before work can be done?

If the earth from the supply is connected to one of the supply cables as it comes into the house, I think this is TNS, but its only 6mm or maybe 10mm, can this be changed by anybody or does the electricity supplier have to change it for 16mm earth cable?

If you know somebody who has the equipment to seal the meters and stuff back up again, would you let them change the tails for you rather than going through the electricity board? Will the board know that you once used to have 16mm tails but for some reason you now have 25mm and they have no record of it being changed?

 

[Qedelec]

Earth coming off the neutral of the supply cable is not TN-S, it is TNC-S (PME).
16mm tails are not necessarily wrong, it depends upon what is required for the property.
Under no circumstances are you to change the meter tails, they are the responsibility of the DNO and they will change them if necessary.
A rewire can be completed without upgrading the tails to 25mm.

 

[MrS]

i thought if the earth came from inside the enclosure where the main fuse is then it was TNC-S (PME) and if it came from a clamp around the main cable that came in it was TNS? i have seen diagrams and read descriptions but never actually seen many or seen actual pictures. i will do a search for some actual pictures. can anybody explain it any better to me? what does a TNC-s and TNS system actually look like?

 

[Steve]

see for reference thread at top of electrics uk section.

 

[MrS]

thanks will do

 

[ban-all-sheds]

What's this got to do with reading up on BS 7671 prior to taking a 2381 course?

Are you sure you're not doing some kind of installation work for which you are not yet fully competent?

 

[andy]

What's this got to do with reading up on BS 7671 prior to taking a 2381 course?

not much. i done the 2381 2 years ago and very little of these questions came into it...