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Electrical Fault Finding. R.C.D. Randomly Tripping Off.

Zoomup

Well it did. Trip off randomly I mean. A split load consumer unit and the offending R.C.D. tripped off three separate circuits. 1. Some bungalow lights. 2. Heating system and oil boiler plus immersion heater fed from ring final. . 3. Single radial circuit to one single socket supplying the washing machine.

Number 2 showed strange insulation tester readings. I suspected the tester. I then used a different insulation resistance tester and got the same strange fluctuating readings. The reading went from high to low resistance. I suspected water in an outside light. I tested stuff in the garage which was fed from the ring and found the fault. It was not water or electronic breakdown of an outside P.I.R. light.

The fault which has been there for 30 years was found inside an old fluorescent fitting.

You'll never guess just what happened. A prize to the winner.

old fluorescent light circuit - Bing

 

Z.

 

 

 

  • 0
    90cf89ed96aa7c7750584f6f060b56d8-original-img_20210623_163807.jpg
    One of these perhaps?
  • 0

    OlympusMons: 
     

    90cf89ed96aa7c7750584f6f060b56d8-original-img_20210623_163807.jpg
    One of these perhaps?

    A good guess. I have come across many cases of rats, mice and squirrels damaging cables in lofts by eating the insulation. Sometimes the rodents eat the rubber or P.V.C. insulation, and even sometimes eat right through the conductors as well. In this case the reason is even more unusual and unpredictable.

    Clue. N-E fault.

    Z.

  • 0

    Was it the old condenser in the fitting had a split in it's plastic cover and was sometimes making contact with the earthed casing? Or was a slightly leaky roof randomly passing enough  water to increase leakage current??

  • 0

    Kelly Marie Angel: 
     

    Was it the old condenser in the fitting had a split in it's plastic cover and was sometimes making contact with the earthed casing? Or was a slightly leaky roof randomly passing enough  water to increase leakage current??

    Yep, it was a power factor capacitor problem. Well associated with it anyway. The neutral lead from the main terminal block had come adrift from the push on pin on the end of the capacitor. Its bare end had somehow found its way onto the earthed metal spine of the batten fitting and was causing an intermittent N. to E. short. I suspect that when the freezer turned on in the early hours it caused the R.C.D. to trip off as some of its current went directly to earth rather than via its neutral back through the R.C.D. I found this by chance whilst looking inside the old fluorescent fitting.

    Z.

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