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  1. sweet212
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    sweet212 EF Member

    Location:
    wiltshire
    Evening all,

    Visited a customer yesterday who said their lamps were blowing regularly in the living room light fitting. I took the light fitting down and visually it looks fine. Its a metal fitting with 3 arms with an SES lamp holder on each. I removed the lamps and insulation tested the fitting with 999+Mohms as the result. All good. I then turned my attention to the wiring. R1 R2 from the light point to the board was 0.62. Insulation res for the circuit was 999+Mohms L-N, L-E, N-E, (lamps removed). Zs from the light was 0.88. Supply polarity is fine and the Ze is 0.22.

    However there is a voltage of 58V showing from the SW line to earth when the switch is turned off.

    The feed has been taken to the light point in t&e and a 3core cable has been taken to the switch. This is a permanent live, neutral and SW line back to the light. A live and neutral is needed at the switch due to a t&e leaving it to feed the kitchen light switch. I disconnected the 3 core either end and insulation res tested it. Again 999+Mohms was the result. When the permanent live is connected at the light point the SW line in the cable becomes live at 58V even though is completely disconnected each end.

    I am returning tomorrow to have another look.

    Any input would be helpful.

    Regards

    James
     
  2. Leesparkykent
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    Leesparkykent You Rock Gmes Staff Member Trusted Advisor

    Location:
    Kent
    Capacitive coupling.
     
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  3. sweet212
    Offline

    sweet212 EF Member

    Location:
    wiltshire
    Yes that is my thinking, but Ive not seen it on this scale. It is possible though because the permanent Line and SW line are the red and yellow cables. This will be my first port of call in the morning.

    Thanks

    James
     
  4. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    take an analogue meter with you.
     
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  5. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    Regular blowing of bulbs should be remedied by fitting led bulbs .... Or not buying them from cheap outlets
     
    • Agree Agree x 7
  6. wirepuller
    Offline

    wirepuller Trusted Advisor

    Location:
    south uk
    One of the most common domestic calls is 'lamps blowing all the time, must be the wiring'
    99% of the time it's rubbish lamps and can be diagnosed and advised upon without a visit.
     
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  7. PEG
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    PEG Trusted Advisor

    Location:
    Manchester
    Hi James,what device was used to measure that voltage?
     
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  8. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    Why are you doing all those tests when the problem you've been asked to look at is the lamps blowing?
     
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  9. Lucien Nunes
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    Lucien Nunes Mercury Arc Rectifier Trusted Advisor

    Location:
    London
    Indeed. What was the supply voltage?
     
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  10. andyb
    Offline

    andyb Electrician's Arms

    Location:
    West Sussex
    Lamps blowing will be one of 4 things
    1, Rubbish lamps (most common reason)
    2, Poor light fitting design, not letting heat escape.
    3, High voltage.
    4, They don't keep blowing, the customer dosn't remember which lamps they change.
     
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  11. KEV 1 N
    Online

    KEV 1 N Regular EF Member

    Location:
    Durham
    Yeah, I often get asked "why do my bulbs blow all the time?" Usually there cheap pound shop stuff or the lights are on and off a lot. Wiring shouldn't cause them to blow, although if there's a lot of vibration on the ceiling above, that may affect the life of an incandescent bulb (I mean lamp, bulbs go in the garden!)......tell them to get LED lamps..
     
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  12. Strima
    Online

    Strima Electrician's Arms

    Location:
    St Neots
    Bulbs grow, lamps blow...
     
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  13. andyb
    Offline

    andyb Electrician's Arms

    Location:
    West Sussex
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  14. anthonybragg
    Offline

    anthonybragg Electrician's Arms

    Location:
    NORTHAMPTON
    Business Name:
    CHARLTEC ELECTRICAL LTD
    I assume that the lamps are of the halogen type and therefore the SES screw cap expands and contracts with the heat generated when left on for some time. This makes a small gap between the live contact pin and poor contact reducing lamp life.
     
  15. HandySparks
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    HandySparks Trusted Advisor

    Location:
    Hampshire
    Business Name:
    Neish Electrical Services
    What do you think the mechanism would be for the reduced life under these circumstances?
     
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  16. anthonybragg
    Offline

    anthonybragg Electrician's Arms

    Location:
    NORTHAMPTON
    Business Name:
    CHARLTEC ELECTRICAL LTD
    This is information given to me by a lamp manufacturer a few years ago.
     
    • Informative Informative x 1
  17. PEG
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    PEG Trusted Advisor

    Location:
    Manchester
    ...I bet it has the word "sprung" in it...:)
     
  18. Des 56
    Offline

    Des 56 Trusted Advisor

    Location:
    Gliese 581C
    The problem is called modern living,its not in the makers interest to have the quality too high so that it destroys the market
    Its like cars fridges,washing machines etc,the manufacturer needs to sell their product both now and in the future,the poor old wiring or fitting often gets the blame
     
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  19. static zap
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    static zap Regular EF Member

    Location:
    west midlands
    As "sweet212" states "..... their lamps were blowing regularly in the living room light fitting............... "

    Check the mechanical action of the light swich (if it hasnt be changed)

    ...some people gently use light switches
    with mutiple loads can degrade contacts , doesn't show up every time /different user!
    ( Customer may not notice buzzing ... multiple on/off wear)

    ..but naff lamps /pooly fitted as per others comments....more common cause
    ( some fittings bake cheap lamps - look for arcing/black-dot on solder blob of bulb)
     
    Last edited: Sep 19, 2017
  20. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    i blame it all down to these modern pesticides. how can a bulb flourish when it's bombarded with chemicals? no wonder we get things like this mutation.
    [​IMG]
     
  21. Des 56
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    Des 56 Trusted Advisor

    Location:
    Gliese 581C
    Nice to see you still have all your teeth Tel
     
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  22. davesparks
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    davesparks Trusted Advisor

    Location:
    guildford
    It is not a reduction in lamp life, the poor connection of the spring contact results in the lamp not illuminating as there is no longer a contact with the live pin.
    The uninformed idiot (householder) assumes that the lamp has failed as it has not illuminated and so replaces it. By replacing it they make a poor connection with the weak spring contact which lasts a short amount of time.
    Then they replace the lamp again and the same thing happens.
     
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  23. ashg285
    Offline

    ashg285 Regular EF Member

    Location:
    manchester
    Go to a lot of jobs where its the bulbs, ask customer where did they get them from and a very common answer is the pound shop :tired:
     
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  24. ye oldie sparks
    Offline

    ye oldie sparks Regular EF Member

    Location:
    sussex
    Ha ha, I remember our old store man saying " Bulbs are for gardens - lamps are for light fittings sonny now what do you really want, if its bulbs your in the wrong ****ing shop".
     
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  25. Paul P
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    Paul P Electrician's Arms

    Best one I had was every bulb I fit goes bang. Looked at the lamp and it was a 110v one.
     
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  26. dmxtothemax
    Offline

    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    Lamps / Bulbs ?
    Who cares what the customer calls them,
    So long as they pay there bill
    They can call it anything
    Happy to take there money !
     
  27. DPG
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    DPG Electrician's Arms

    Location:
    S Yorkshire
    Their.
     
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  28. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    now there's being pedantic, and their's being pedantic.:D:D:D
     
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  29. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    Don't speak English !
    I speak STRAY-UN !
    :thumbsup:
     
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    • Funny Funny x 1
  30. sweet212
    Offline

    sweet212 EF Member

    Location:
    wiltshire
    Evening all,

    Thank you for all the replies. I have since been back and corrected the problem. By swapping 2 of the cores over in the cable the 58V disappeared.

    I also changed the Wilko lamps over for some Osram ones. Hopefully they will last a while longer.

    Great knowledge and information shared by everyone who posted.

    Thanks

    James
     
    • Like Like x 1
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