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Discuss Lighting strike on property. high ZE and arking when testing. in the New Member Introductions area at ElectrciansForums.co.uk.

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  1. Jakegood
    Offline

    Jakegood Regular EF Member

    Location:
    Kent
    Business Name:
    No e
    hi,

    As the title states. Earlier in the week I was sent to a property to do a routine EICR test. When I arrived at said property I was informed that it had recently been struck by lighting! The lighting had split the roof pearling, and done substantial damage to the roof trusses, before finding its entry point below bathroom window. When performing ZE I was getting reading all over the place from 0.45- 0.87, this is on a TNCS system, which is obviously unacceptable. The test also resulted in arking from the main switch. The Tennant said someone had been out and looked at the 35mm tails to and they were damaged and cut back and re terminated. The only thing I can think of saying is there is damage to the incoming side, and to get in touch with the provider before we do the test. Any advice on how a lighting strike caused this?
     
    • Bad Spelling Bad Spelling x 1
  2. westward10
    Offline

    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    A lightning strike when it hits a building can pass through the walls to the system cpcs, lightning protection with a main protective bond diverts the strike away from sensitive cpcs to ground.
     
    • Informative Informative x 1
  3. Vortigern
    Offline

    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    Are you sure the person who cut back and re-terminated the tails tightened up properly?
     
    • Optimistic Optimistic x 1
  4. Strima
    Offline

    Strima Electrician's Arms

    Location:
    St Neots
    Lots of volts and lots of amps during a strike, I would guess there would be substantial damage to electrical equipment including switches and other devices.
     
    • Like Like x 2
  5. Jakegood
    Offline

    Jakegood Regular EF Member

    Location:
    Kent
    Business Name:
    No e
    Hi,

    Yeah, double checked the tails, all good. It has obviously to with the lighting strike. Just wanted to know why exactly it would cause the arking and the high ZE??. My supervisor just said they had to contact the provider.
     
  6. plugsandsparks
    Offline

    plugsandsparks Electrician's Arms

    Location:
    Chesterfield
    were your reading taken on the incoming side of the main switch ?
     
    • Like Like x 1
  7. buzzlightyear
    Online

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    If it was a lighting strike would the meter be fride crisp and dryed.
     
    • Like Like x 1
  8. Wilko
    Online

    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Hi - when you asked "how can lightning cause this?" it got me thinking. One on line ref. said av lightning bolt to gnd has 10^^9 Joules of energy. Now that might be total bs, but if it was true that's 1,ooo megawatts for 1 second. More than enough to toast anything it feels like.
     
  9. Richard Burns
    Offline

    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    If you were performing a Ze test then there should be no test current flowing through the main switch and so no arcing. I am assuming the main switch is on during the test.
    If test current is flowing through the main switch this would indicate a low resistance path line to earth (or line to neutral if your tester also performs PSCC at the same time) on the load side of the main switch (i.e. within the installation).
    I would initially suspect, especially with the tails damage, that the main switch is damaged internally.
    The high voltage from the lightning could easily arc across large gaps and cause damage to the copper inside the switch even away from the contact faces.
     
    • Agree Agree x 3
  10. buzzlightyear
    Online

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    Me thinks all of the wires would be wielded . in the cu board right down to main cut out
     
    • Agree Agree x 1
  11. essex
    Offline

    essex Regular EF Member

    Location:
    Wiltshire
    First thing Inwas taught about fault finding is to forget whatever you have been told.

    So ignore the lightning. It has no impact on your job.

    Speak to the DNO to see what they say and if they say that is the earth younare getting then carry out your periodic inspection and code appropriatly.
     
  12. Strima
    Offline

    Strima Electrician's Arms

    Location:
    St Neots
    True in a lot of situations however I think sa lightning strike maybe a slight indicator to what faults might be existing on the installation.
     
  13. essex
    Offline

    essex Regular EF Member

    Location:
    Wiltshire
    If it is true and even if it is it has no relevance to the periodic inspection.
     
  14. Strima
    Offline

    Strima Electrician's Arms

    Location:
    St Neots
    I disagree, knowing what sort of damage can occur from a strike you can pay even more attention to that. Same as flood damage I would inspect all circuits however take a closer look at those circuits immediately effected by the flood.
     
    • Like Like x 1
    • Agree Agree x 1
  15. essex
    Offline

    essex Regular EF Member

    Location:
    Wiltshire
    I don’t follow mate. Your tests should be the same regardless of the issue that ‘may’ have effected it. Either the circuit is safe for continued use or it is not. What further testing would you do following a ligtning strike that you would not do as part of a standard PIR?
     
    Last edited: Aug 11, 2018
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