Cable on fire

Discussion in 'Electricians' Talk' started by Dazz, Mar 12, 2015.

  1. Dazz

    Dazz New Member

    Fault finding today

    Lighting circuit burnt through at 8 x places, isolate at the midpoint with faults both sides, split circuit into 6 individual sections and all showed a dead short between these conductors. Mains details PME system with a 5A type 1 MCB in the consumer unit -:

    An inspection in the roof revealed the wiring passing through the loft insulation had completely burnt through, with no visible insulation on the wiring.


    3 hours and many checks later the cause was found to be an over heating neutral conductor at the cut-out. The neutral current, which could have been around 65A returning via a neutral to earth fault on this lighting circuit.

    Any stories your end of open circuit PME systems
     
    Last edited: Mar 12, 2015
    FatHands likes this.
  2. FatHands

    FatHands Well-Known Member

    Blimey Dazz, good spot. Did it look like it had been meddled with then?
     
  3. Rulland

    Rulland Screwfix Select

    Some pics if possible please Dazz.
     
  4. JP.

    JP. Screwfix Select

    Ure aving a bubble Dazz
     
    Last edited: Mar 13, 2015
  5. Lectrician

    Lectrician Screwfix Select

    Had very similar in a building split into two properties. Lighting circuit fuse blown, insulation resistance flat down.

    Starting splitting circuit as you do, splitting L and N but leaving earths connected. Each section showed faults. Disconnected one length of cable with the intention of pulling through a new one (no access above). As I disconnected the earth, it sparked like hell.

    The neutral to this property was lost, and as it had been poorly split from the other half which had a new supply, the earths on the lighting circuit where still common. The installations current was flowing back down the earth of the lighting circuit, to the neighbouring property, through their earths and to their cutout. Nasty.
     
    FatHands likes this.
  6. flateric

    flateric Well-Known Member

    And then on top of that when you give someone the bill or a quote to correct it all they moan :(
     
  7. Lectrician

    Lectrician Screwfix Select

    Found a pic of the burnt out T&E I came across.

    [​IMG]
     
  8. stateit

    stateit Screwfix Select

    Try these:
    [​IMG]

    [​IMG]

    [edit] Or not... I'll try again...[/edit]
     
  9. stateit

    stateit Screwfix Select

    Try these:
    [​IMG]

    [​IMG]
     
    Last edited: Mar 23, 2015

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