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Light sockets

Former Community Member
Former Community Member
Something that has puzzled me for years.


Bayonet cap and Edison screw light bulbs can be removed without tools thus exposing potentially live terminals and presenting a distinct shock hazard.  made worse by the fact that you often need to stand on a chair to remove the bulb.   There are millions of these installed yet the regs seem quite happy with the situation.
  • 0
    Indeed so. But the standard for lamp holders is not the responsibility of the same folk who write the regs.


    You can get more expensive lamp holders that have dead pins when the bulb is removed, but most of the ones out there are not finger proof,and the safety ones are not mandatory.


    I suspect it is history,  you would not dare do it now, but you can because it has been OK, demonstrably,  for years.

    Similarly, if cars did not exist and we went to the Health and Safety folk to review a proposal for a new personal transporter  that had 25kV sparks, a hot exhaust and enough volatile fuel to put the driver into orbit stored in a single skin tank 4 inches above the road, you'd not get very far either.. But the main cause of accidents is not any of that, its concentration, or lack of.

    Mike.
  • Former Community Member
    0 Former Community Member
    mapj1:

    Indeed so. But the standard for lamp holders is not the responsibility of the same folk who write the regs.


    You can get more expensive lamp holders that have dead pins when the bulb is removed, but most of the ones out there are not finger proof,and the safety ones are not mandatory.


    I suspect it is history,  you would not dare do it now, but you can because it has been OK, demonstrably,  for years.

    Similarly, if cars did not exist and we went to the Health and Safety folk to review a proposal for a new personal transporter  that had 25kV sparks, a hot exhaust and enough volatile fuel to put the driver into orbit stored in a single skin tank 4 inches above the road, you'd not get very far either.. But the main cause of accidents is not any of that, its concentration, or lack of.

    Mike.


    Whose responsibility is it.


    I was once reluctantly made responsible for PAT testing in my workplace.  After I had condemned 20 plus reading lamps - including the bosses very expensive designer model - for having live parts accessible without tools they took me of the job


    As for cars:  they have been continually upgraded for increased safety over the years whereas Edison or Bayonet themselves would recognize a modermr lampholder


  • 0
    "Bayonet"  a friend of Bob Transformer
  • 0
    To be fair you can drive a 1920s car on the road here, and maybe changing pre-synchromesh gears is a bit fiddlier, but the operation of the basic 4 cylinders gas clutch and brakes and all that  are much the same. 

    I do not think there was a Mr Bayonet - the connector is based on the quick coupling on the end of the British Army Rifle used to attach a pointy thing so that when you had run out of bullets you still had a weapon for close combat. Bayonet connectors turn up in other disciplines too, like compressed air.


    So who writes the lampholder standards ?

    well

    UK lampholder standard   Committee CPL/34/2
    Screw lampholder standard  Committee CPL/34/2


    You may think that is expensive for 80 pages of which most is the same as the last edition...

    more on that committee


    I suspect you exceeded your remit with the PAT fails - normally parts meeting another accepted standard are considered out of scope of test.


    ( I just need a standard for a pair of upturned forks on a piece of floorboard that can be livened up by push button to cook sausages etc so I can make my scouts 'danger of electricity' demo fully PAT compliant.. ?  Pickled Gherkins go well too, you get a sort of internal thunderstorm with a bright orange tint that I assume is at least in part from the sodium D lines around 589nm from the salt in the pickling solution.)


    Regards Mike.
  • Former Community Member
    0 Former Community Member
    Bayonet is the angliseation of the French word baïonnette.   Bayonet connectors are common in RF engineering like the classic BNC connector


    Is there nothing in the regs that says live parts must not be accessible without tools?

    If not most EICRs are straining at a gnat and swallowing a camel
  • 0
    I think this is a case where you have to be a bit sensible i appreciate that the standard BC lampholder is not ideal from a safety point of view but people are aware that there is some risk  and to be fair they are definatley better than edison screw fittings  so I think we've got the best of an imperfect system.
  • 0
    ebee:

    "Bayonet"  a friend of Bob Transformer




    The one who wears a skirt in the Home Office.


  • Former Community Member
    0 Former Community Member
    My point is that there are far less dangerous situations which get C1 because an EICR assumes that people are neither sensible nor risk aware.


    Neither the Edison nor bayonet cap lampholder is properly engineered.  The idea of transmitting the insertion force through a weak glass to metal bond is ludicrous.  As is borne out by the number of times an attempt to remove an old bulb results in the glass coming away in you hand and leaving a metal piece which can only be removed by using pliers.  A sensible design would use a clamping lever which locked the bulb in place after it had been inserted with zero force


    But, as in so much domestic electrical installations, cost triumphs over safety and convenience
  • 0
    Bayonet lamp holders have been in general use for over 100 years and in practice have a good record of safety and reliability.

    Screw in types also, though arguably less safe.

    The great merit of BC types is that the lamp can not work loose under vibration.

    Screw types have the merit of being inherently polarised and also that the light may be extinguished by partly unsrewing the bulb.


    Neither type is meant to be used on more than 250 volts.
  • Former Community Member
    0 Former Community Member
    broadgage:

    Bayonet lamp holders have been in general use for over 100 years and in practice have a good record of safety and reliability.

    Screw in types also, though arguably less safe.

    The great merit of BC types is that the lamp can not work loose under vibration.

    Screw types have the merit of being inherently polarised and also that the light may be extinguished by partly unsrewing the bulb.


    Neither type is meant to be used on more than 250 volts.


    Both types are notorious for the glass separating from the glass when removing them.  Especially if they are used in situations where corrosion can occur such as automobile applications.  But if it was good enough for great grandad ...


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