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High Ze on TNS supply for flats (3 ohms)

aligarjon

Hi guys.  I carried out an EICR on a first floor flat today.  (1 of 4 flats in the building plus landlords supplies).  The intake position is in a cupboard on the ground floor and is some sort of TNS setup. It isn't something i have come across before as it looks pretty industrial which isn't what i do.  I will try and post a couple of pictures after my post.  I am not sure that the earth connection looks original so wondered what others thought.  It looks pretty corroded so hopefully is an easy fix if the DNO will look at it. 

The problem i am going to have is the CU in the flat will need swapping, if the dno won't fix this issue i will need to fit some sort of rcd to the sub-main to a rental flat in an external cupboard where there is zero space for one.  I am hoping they are still responsible for maintaining the earth.  It obviously feeds other flats in the block as well as a landlords area that actually has a night storage heater in Slight smile.  My thoughts are there are potentially areas in the building that are potentially dangerous, starting with a metal storage heater with a high Zs.

Parents
  • 0

    3 ohms . Well that will struggle to blow the 150A incoming fuses, or even the outbound ones above each meter. I presume the black singles between the main head and the cream colored phase splitting are rubber/cotton clad.

    Verify the earth connections to, but please do not open, any of the cast iron stuff - it looks rather like it may be from the asbestos era.

    Assuming it really is the incoming that is poorly earthed, and not one a rusty bolt you can just replace or tighten from the outside as it were, then I'd get the DNO to look at it. Mention the phrase 'not earthed'

    They may say "bad luck, go TT " but if they do try and  get it in writing, and then if they do you probably need to involve the freeholder, because, as you say, then really all of the building needs RCD cover.

    Mike.

Reply
  • 0

    3 ohms . Well that will struggle to blow the 150A incoming fuses, or even the outbound ones above each meter. I presume the black singles between the main head and the cream colored phase splitting are rubber/cotton clad.

    Verify the earth connections to, but please do not open, any of the cast iron stuff - it looks rather like it may be from the asbestos era.

    Assuming it really is the incoming that is poorly earthed, and not one a rusty bolt you can just replace or tighten from the outside as it were, then I'd get the DNO to look at it. Mention the phrase 'not earthed'

    They may say "bad luck, go TT " but if they do try and  get it in writing, and then if they do you probably need to involve the freeholder, because, as you say, then really all of the building needs RCD cover.

    Mike.

Children
  • 0 in reply to mapj1

    Thanks Mike.  I didn't touch anything other than remove the lid of the KMF of the flat i was testing so that i could see if my high earth at the flat was from a problem with my sub-main  or at the supply end.

    Gary

  • 0 in reply to mapj1

    I will leave it with the client to sort out with the supply company for now, i clearly can't fit a metal consumer unit in the flat  at the moment.  I was thinking about TT, which would be difficult to say the least for a first floor flat and the mains in the the centre of the building. 

    My other thought would be i could not get anywhere near 3Ω with a spike, so just add the rcd if i can magic some space in that cupboard.  Then there are the other 4 unearthed flats of course.(which aren't my concern for now)

    Disappointed

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