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line-neutral insulation resistance test

Discussion in 'Electrics UK' started by abinath, 15 Jan 2018.

  1. abinath

    abinath

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    Morning

    On a house that I am attempting to buy, the previous owner supplied me with a domestic electrical installation condition report from 2012 that has the comment:

    'no line - neutral insulation resistance test on lights'.

    Should I be concerned about this, from a safety point of view ?
    I wonder why this test was not done ?
    Also, I need a clean certificate for insurance purposes, because it is thatched.
    I know from my own examination that the socket circuits are twin earth cable, but the lighting circuits have no earth wire. Again, should I be concerned about that ?

    Many thanks
     
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  3. bernardgreen

    bernardgreen

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    Yes, especially if the lighting circuit has PVC cables in the roof space. Failed insulation between Live and Neutral ( or between Live and Earth ) can create a short circuit with arcing ( sparking ) that will ignite the roof.

    Many insurance companies will not accept PVC cables in the roof space of a thatched house. They require rodent proof cables.

    It may be that the previous owner did not have insuranc or had not informed the insurance company that the wiring of the lights had not been tested

    Similar situation to the thatched cottage I bought in 2011. I did a complete re-wire, with no cables in the roof space, upstairs rooms have wall lights and standard lamps.

    Edit ..tiepin error corrected
     
    Last edited: 15 Jan 2018
  4. JohnW2

    JohnW2

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    One can but guess. Are there perhaps dimmers or other electronic gizmos in the circuit which the electrician undertaking the EICR feared might be damaged by (and/or would upset the results of) such testing (which is normally undertaken with 500V)?

    What you go on to say (no earth in lighting circuits) would explain the absence of line-earth and neutral-earth IR tests - is it conceivable that the person wrote down the wrong thing?? You should have a schedule of test results - does that indicate no results for lighting circuits?
    It's obviously not up to current standards/requirements, and has not been for a long time, but there is no requirement to update to meet the current requirements. Other than the above comment, the main consequence is that you cannot (should not) have any metal light switches or light fittings etc. (unless they are 'double insulated) on a lighting circuit without an earth.

    Kind Regards, John
     
  5. mwatsonxx

    mwatsonxx

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    :rolleyes::rolleyes: mor bad spelin, he's not going to be happy.:ROFLMAO::ROFLMAO:
     
  6. Iggifer

    Iggifer

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    Not even dimmers or electronic gizmos, I suspect he couldn't be bothered to go around the house taking all the lamps out!

    LED spots are another reason you'd struggle to do it. Without a click-flow or similar on the back of the fitting it's near impracticable.

    If there is genuinely no CPC on the lighting circuit I wouldn't worry too much as it's near enough due to be rewired anyway, I'd just bear that in mind when making my offer.

    And an EICR on an installation of that age is now expired if it was carried out in 2012 so it wouldn't hurt to have another one carried out
     
  7. Risteard

    Risteard

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    It is wholly abnormal to insulation test between live conductors during Periodic Inspection and Testing.
     
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  8. JohnW2

    JohnW2

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    Wholly abnormal? If that were the case, why would there be a column for recording the result of such a test in the standard Schedule of Test Results form?

    Kind Regards, John
     
  9. OwainDIYer

    OwainDIYer

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    Smoke detectors on the lighting circuit?
     
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  11. John D v2.0

    John D v2.0

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    Just for convenience if you want to record it.

    There are columns for end to end ring resistance too, etc. The form is not a checklist, just a useful form for results.
     
  12. abinath

    abinath

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    Thanks for all your comments, guys.
    I've just learned from the insurer, who also insured the property through the previous (deceased) owner, that the test results are satisfactory for insurance purposes, though she wouldn't tell me any more due to data protection. There may have been remedial work that I am not aware of atm.
    Worryingly, she says that the test certificate is valid for 10 y, ie until 2022, even though it may not be compliant to modern standards. So, the pvc wiring in the roof space would not be acceptable if the test were carried out today, but they have to accept it. Meaning that I may be liable for improvements in 2022. But it is hard to make the case that the seller should pay for improvements now.
     
  13. JohnW2

    JohnW2

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    Possibly. However, I'm still far from convinced that it is "wholly abnormal" to undertake such tests as part of an EICR.

    I would have thought that it would be particularly worth considering a L-N IR test in a lighting circuit with no CPCs, not the least because it's the only IR test (of the cable) that could be done. It's probably far less important with T+E, since the structure of such cable is such that it is very unlikely that there would be any sort of L-N fault which would not also involve the bare CPC, so that L-E or N-E tests would nearly always pick up a problem.

    Kind Regards, John
     
  14. JohnW2

    JohnW2

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    I'm not so sure about that. If it's the case that you are going to suffer expenses 4 years down the road in order to render the property insurable, I would certainly think that it would be a valid point to introduce into negotiations over price.

    Kind Regards, John
     
  15. Iggifer

    Iggifer

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    I would arrange to have your own EICR carried out at your own cost - in the grand scheme of things it's not a lot of money.

    You already know the lighting circuit is going to need a rewire in the very near future, and you're looking in the region of £1500-2000 for that (just a ballpark figure, I don't know the first thing about the house).

    If your EICR confirms this then that's only going to help your case.

    Generally the only time a certificate is valid for 10 years is when it's first issued, ie and installation certificate. You CAN issue an EICR that's next test date is 10 years, but realistically you'd only do so on an immaculate installation, for example, installed in say 2007, all RCDs, no alterations and no damage visible. Almost all to current standards. You could maybe give that 10 years at a push. More likely would be 5. The insurers assertion that it's valid for 10 years may simply be based on what's written on the certificate, with no actual knowledge as to the guidance.

    How much of the EICR do you have? If you want to share what you have, we can pick holes in it and you can use this as an argument as to why it's no use (I do love a shoddily filled out certificate)
     
  16. JohnW2

    JohnW2

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    Whilst I agree in principle with most of what you say, it sounds as if (rather strangely) the insurer has said that having PVC wiring in the thatched roof at the time an EICR would not be acceptable.

    Why the EICR (or its date) has got anything to do with that, I don't quite understand. The insurer could presumably refuse to insure a property with PVC wiring in a thatched roof now, if they wanted to, regardless of the date of any EICR.

    Kind Regards, John
     
  17. abinath

    abinath

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    Thankyou Iggifer
    I am trying to get hold of pages 2 and 3 of the certificate. I gather those two pages actually record the resistance measurements taken. Hard to imagine they could have been left blank.
    You are right, the certificate was for 'Change consumer unit and test', ie a brand new consumer unit. But the circuits pre-date the new consumer unit by many years, yet they are covered by a 10 year certificate for replacement of the consumer unit. Fortuitous for the owner, though she's now handed in her dinner pail. The recommendation on p1 was to further inspect and test after 10 years. Your are right, the insurer has seen that 10y, and have to accept it apparently. They don't feel they need to consider how standards may have changed in that time.
     
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