ze 1.9ohms

[daz1963]

just been to quote for a added socket. nice new 17th edition board, so thought all should be ok. quick check of efli gives me a zs of 2.2ish ohms.same on a few more sockets. so goes to main board and checks ze,which is 1.9 ohms. a tad to high for tn-s at 0.85. now if this was a tt system that would fine. as its a tn-s would you contact the dno to rectify it? or would you leave alone and add the socket as its rcd protected? i will ring the dno and see if i get anywhere with them which i doubt.just wandered what anyone else would do.now be honest:wink5:

 

[mike the sparky]

There are also issues where overheads are supplied to multiple properties "loop in-loop out" where potential earthing problems arise if a broken neutral occurs. This can also cause nuisance RCD tripping on neighbouring properties.

 

[Engineer54]

Why would they be looping in/out, when being fed from an overhead supply?? I think your getting confused with a ground supply system, that's the only time i've seen service cut outs looping to the next property, and even that was a long time ago.

 

[bradder]

i have seen a few installations that have had service cut outs looped on an overhead supply. mainly terraced houses with an overhead supply feeding one house then clipped along house to next house

 

[mike the sparky]

I look after 2 properties 20 miles apart, both are terrace farm houses & both are fed overhead to the first building which is then "looped in-looped out" of the remaining 2 properties. DNO inform me that PME is not available because of the risk of a broken neutral which could affect the other properties.

 

[Engineer54]

More fool to the DNO's then, what a waste of cable!! i see that were talking about very rural situations here, where maybe these rows of terrace houses were fed from the end of an overhead string. ....If not, i can't see what the advantage was, wiring these houses that way... lol!!