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Design voltage of incandescent lamps

broadgage

As is well known, the nominal or declared voltage of UK low voltage mains was reduced from 240 volts down to 230 volts, some years ago. Nothing much actually changed though and the measured voltage still tends to be 240 volts most of the time in most places.

But what  is the design voltage of mains voltage incandescent lamps for the UK market ? is it 230 volts or 240 volts. Is the light output and service life measured at 230 volts or at 240 ?

If a lamp designed for 230 volts is burnt at 240 volts the life will be significantly reduced.

If a lamp designed for 240 volts is run from an actual 230 volt supply, then the light output will be significantly reduced.

Incandescent lamps are now much less used, but there is still a substantial market via a number of loopholes. Traffic signals still use incandescent lamps.

  • 0 in reply to Andy Millar

    Funny how when a subject comes up it immediately pops up again...I was helping a colleague with their CEng application this morning, and one of their bits of evidence is that they led a team who developed from scratch a rail signalling interlocking system in Turkey. We were looking for an example of consideration of sustainability, and they pointed out that they had introduced a new feedback and monitoring and control system in their interlocking logic to allow the use of low energy LED signals, including the safe detection of failures. I did smile at the coincidence that I'd only just written about that, not having thought about it at all for several years...

  • 0 in reply to Sergio Fernandez

    I do feel like I've entered a bit of a time warp here, basically don't panic - all these issues were very thoroughly worked through around 20 years ago...probably longer in the highways world.

    And yes, where applicable railway LED signals (or more accurately their control and monitoring functions) are SIL4.

    I do remember one of my my colleagues in the early 2000s saying that LEDs could never work in rail signalling but he was a) a mechanical engineer and b) rather thoroughly proved wrong.

    Cheers,

    Andy

    (formally UK Engineering Manager / Product Manager for (amongst other things) incandescent rail signals for a major manufacturer...delighted that that part of the role is now obsolete) 

    wallywombat said:
    One advantage of incandescent bulb traffic lights is that they are much better at melting any snow which has accumulated on or around the lens.

    P.S. On this point, the person I mention above did also, quite correctly, regularly point out that the problem is that road traffic lights are the wrong way up! The problem doesn't arise with rail signals (at least as far as snow blocking the red signal which is the important bit).

  • 0 in reply to Sergio Fernandez

    One advantage of incandescent bulb traffic lights is that they are much better at melting any snow which has accumulated on or around the lens.

  • 0 in reply to mapj1

    Thank you Mike Smiley Yes the big stuff is my day job with industrial electron accelerators up to 3MeV, The very big stuff was a visit to the Diamond Light source as part of a radiation safety traing course.

    This is the hobby stuff in action, a 12cc petrol injected twin cylinder engine undergoing some load trials:

    https://youtu.be/7RVp_fwLo0o?si=o75XRC3gcp8_d4Zf

  • 0 in reply to Roger B

    Most impressive - the machining and steam engine bits are presumably at home, and the things with HV grading rings and a gantry crane are presumably work related - if not I'm envious as well.
    Mike.

  • 0 in reply to mapj1

    The full Geek in my cellar.

    https://flic.kr/p/FJK5pt

  • 0 in reply to mapj1
    mapj1 said:
    You don't keep ferric Chloride in a bottle under the sink by any chance?

    There's a limit to what my wife lets me keep in the kitchen. But a few things in the fridge which are clearly labeled up as not for eating. I try to minimize harzards at home for obvious reasons.

  • 0 in reply to Keir Stitt

    hah I detect a fellow traveller.

    You don't keep ferric Chloride in a bottle under the sink by any chance? There are similar points on the hardware geekscale to be earnt by having a lathe at home, and the combination of a lathe and mini-mill is a point multiplier.

    MRelaxed

    PS I'm teasing and not at all saying that is a bad thing - I can claim a Variac (20A model, from a skip dive) the ferric chloride (and the HCL to spike it when it starts to fade), the lathe and a small bandsaw, as well as 2 scopes, spec an and  VNA and 2 RF sig gens.

  • 0 in reply to mapj1
    mapj1 said:
    Its smaller/ easier than the variac, and less heat than the resistor.

    Yeah I was thinking variac simply because I have one under my desk.

  • 0 in reply to Keir Stitt

    Its not just the lack of neutral - because the LED light power supply starts with a bridge rectifier and a capacitor, the dimmer sees a very odd current waveform, and indeed at the moment the triac firing circuit triggers, there may be no current at all if the cycle has yet to reach a voltage that exceeds the smoothing capacitor voltage so the bridge is not yet conducting. Repeated firing pulses to the SCR do help,  but makes for a very current hungry dimmer - far more then the normal R/C + diac that we normally get that gives one firing spike per half cycle. Changing between leading edge and trailing edge may help, but you still need the dimming device to be turned on and stay on, when there is not yet any load current, and yet to go off at the voltage zero crossing.

    In many ways, the cheaper non dimmable  lamps that are a capacitive dropper, plus a few caps in a box, work much better.

    Mike

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