Cofused earthing arangement

[ajelec10]

Has any body come across an eathing arrangement like this it just cant make its mind up TN-S or TN-C-S
lol.
AJ

 

[mechelec]

It is a TN-C-S system, the cutout is designed for a T-N-S or TN-C-S arrangement and is adaptable, so at some point ( probably when first installed) the DNO has taken an ELI reading and PME'd it by fitting the link. It is no different to having a TT system and appling for a PME they will only insert a link or fit a hepbond clamp on the cable and a link to the neutral. All new joints on the underground network are PME'd anyway with neutral and earth connected. If you test the ze on neutral and earth the difference is usually very small and it will tell you if the network is PME'd.

 

[not clever]

Sorry mate,looked at the picture again.Looks like it may have been connected up wrong.16mm from incomer should go to the board,and then your 10mm to the gas and water supplies.IMO that's what it look's like.Definitely TNS

No No No..the link is in place between Neutral & Met making this a TNC-s PME set up.

There is nothing wrong with the 10mm equi bonds going from their current location off to the service pipework (i would hazard a guess these are the two looping down) & as you rightly say the other should be 16mm (unless adiabatic equation is used to prove a smaller csa can be used) off to the cu.

 

[claire_r]

I would say a TNS as well, looks a little confusing in there but the sheathing makes me think it is. Thats probably a standard box they use for the cut out etc...I came across a TT the other day that looked like that as well, took me ages to justify the 43 ohm zs reading til wandering around outside...hehe bingo!!