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Earth Clamp on incoming cable to provide means of earth. What code and who is responsible.

aargeitakis
Hi all,

first post on the new page.


I am doing domestic electrical condition reports on Council properties  and i am coming across earth clamps on incoming cable to provide means of earth. 

I used to coded  as cat 2 but the side manager says must be cat3 because  he contacted the local REC (Western Power) and they do not want to know. Today property  was an upstairs flat so to put a rod is not and easy solution.


My last experience with them I had to change a fuseboard and the cutout was a very old square metalic with the main switch next to it, in a similar square box

The means of earth at the moment, was a 4mm bare multicore  cable attached to a bolt, on the cut out,and  the ZE was like 250  Ohms. 

So I called them, they went out and said to the customer that the cutout need to be changed. They said to replaced it with TNC-S cut out it will cost 400 pounds. 

The customer called me and said what do you think? I said say no and we will see what cut out they will provide  for free. So of course they fit a cut out without earth so I had to put  an earth rod.



My other point with the REC's is that when they fit a new smart meter they suppose to fit an isolator/one shot too. Must be a local isolation.

A few years ago I did, an one shot course with Npower and I asked the question and the answer was no because we charge 100 pounds per one shot.





I believe is wrong not to provide one shot for free and TNC-s cut out for free because that make the installations safer.


Many Thanks


Paul



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    When you say a one shot what are they?  Just not familiar with hat term secondly I don't think DNOs are responsible for earthing even though in my opinion they should be I think fitting earth rods is your best bet I'm not sure when the rules changed because I know that when the DNO who are SSE in this area fitted a new consumer unit some 10 years ago they also updated the earthing including fitting a  clamp to the metal sheath of the service cable which is our main terminal although I guess you could argue that the miles of lead water pipe are also helping a bit
  • 0

    I am doing domestic electrical condition reports on Council properties  and i am coming across earth clamps on incoming cable to provide means of earth. 

    I used to coded  as cat 2 but the side manager says must be cat3 because  he contacted the local REC (Western Power) and they do not want to know.





    Some kind on connection onto the incoming cable sheath is quite normal and correct for TN-S supplies - quite what the connection arrangement was seemed to vary greatly with time and region - in the old day most liked a soldered (sweated) joint, nowadays constant pressure springs seem fashionable, in between a variety of clamps were uses by the suppliers - some looking very much like BS 951 clamps we'd use on pipework (the suppliers at least know the type of cable they're dealing with so could appraise the risks involved in using a compression clamp).. That of course makes it very difficult to tell the difference between a genuine DNO connection and one that's been made inappropriately by 'some other'. Usually as long as it seems secure and gives a reasonable Ze, I think they're typically left alone.

     

    My other point with the REC's is that when they fit a new smart meter they suppose to fit an isolator/one shot too. Must be a local isolation.



    Ah, it all a bit messy. RECs don't exist any more (at least not on the UK mainland) - there are DNOs and there are electricity suppliers - and typically the suppliers sub-contract the metering side to another separate meter operator. The idea of installing an isolator at the same time as upgrading to a smart meter was discussed apparently, but dismissed as too expensive. Isolation continues to be provided by removing the cut-out fuse (by request to the supplier for the likes of us). Personally I stick isolator in whenever I get the chance - that way the supplier only needs to get called out the once.


       - Andy.
  • 0
    Andy and Kelly


    thanks for your replies
  • 0
    Just an addon to further confirm what Kelly said, it very much depends on the DNO. My local DNO, (and Kelly's),  [SSE], are particularly helpful and will respond typically within hours of a call about inadequate earthing on a TN-S supply. They still seem to install the 2 part brass clamps and supply  a 10 or 16mm tail to whatever MET is available. (they will install a MET block if one is not there, they will NOT interfere with a customer's installation, of course)


    I guess this may depend on area though, we work mostly in Gosport and the TN-S cables seem to be in fair condition.  I guess a new service head is more time for them, so if Ze is okay, a new earth clamp is cheap and cheerful?


    Anything more than that however, such as moving a service, and they'll install a TN-C-S head, and make the splice on the concentric outside the property.
  • 0
    thanks all for your replies!!

  • 0

    MHRestorations:

    Just an addon to further confirm what Kelly said, it very much depends on the DNO. My local DNO, (and Kelly's),  [SSE], are particularly helpful and will respond typically within hours of a call about inadequate earthing on a TN-S supply. They still seem to install the 2 part brass clamps and supply  a 10 or 16mm tail to whatever MET is available. (they will install a MET block if one is not there, they will NOT interfere with a customer's installation, of course)


    I guess this may depend on area though, we work mostly in Gosport and the TN-S cables seem to be in fair condition.  I guess a new service head is more time for them, so if Ze is okay, a new earth clamp is cheap and cheerful?


    Anything more than that however, such as moving a service, and they'll install a TN-C-S head, and make the splice on the concentric outside the property.




    My experience of a high Ze in Gosport was that SSE "PMEed" the service cable on the premises within a few hours. I was astonished by their swift service. I might add that the possibility of a poor connexion between the lead sheath and the earthing conductor appears not to have been considered.

  • 0
    Interesting, maybe they're just fast to respond and diagnose?


    Another possibility is that they give the responding engineer/technician a lot of leeway?


    I get the impression from this august forum that DNO stuff is a lot more 'pragmatic' than BS7671 allows (of which i wholeheartedly approve)
  • 0
    Where I live (The old Norweb REC area) the supplies were a lovely great big lump of sweated solder on the sheath with the earth conductor sometimes resembling a bit of fusewire but if requested they would remake with a 16mm earthwire. Wheras neighbouring YEB was traditionally a simply and earth clamp type thingy and usually had a bit of 2.5 or thereabouts.

    If I find a bad Ze on the incommer I get the installation owner to formally request info i.e earthing type and Ze via the DNO - that sets the whole sorry system in motion cos the often say "Oh we have no records so we will haave to come and inspect and test it" often remaking the connection/digging up the road. ha ha.

    If, on the other hand, you were to report a poor Ze then they try to say it is not their responsibillity to supply an earth.

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