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Wiring Regulations Literary Question

Former Community Member
Former Community Member
Hello all, I wonder if someone can help me please?

https://en.wikipedia.org/wiki/Voltage_optimisation#Overvoltage

I'm trying to get a reference for a section in this wikipedia article to put in a report I'm writing but I can't find the original source. Under the "Common Power Quality Problems > Overvoltage" section there is a sentence that describes "A 230 V rated lamp used at 240 will achieve only 55% of its rated life". From the article I believe it is from the book "Commentary on IET Wiring Regulations 17th Edition" from 2016, ISBN 1849197652.


I have tried to find it in a library as I don't have £90 to drop on a new copy of it, just to see if it is this book I should be referencing in my report, but I've had no luck there. Is there perhaps anyone with this book that knows whether or not the quote does indeed come from it or not?


Any assistance with this query would be greatly appreciated.

Thanks in advance

Alan
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    I've Googled for the phrase "A 230 V rated lamp used at 240 will achieve only 55% of its rated life" - and a piece on TLC's site seems to attribute it to "The Electricians Guide Fifth Edition by John Whitfield " (rather than the Commentary by Paul Cook) https://www.tlc-direct.co.uk/Book/1.1.htm - so not beyond belief it was incorporated into later IET books.


    This too seems to suggest it's the Guide rather than the Commentary that's being quoted: https://books.google.co.uk/books?id=mkk-CgAAQBAJ&pg=PA2&lpg=PA2&dq=A+230+V+rated+lamp+used+at+240+will+achieve+only+55%+of+its+rated+life&source=bl&ots=MH94OjON0W&sig=ACfU3U1MB4MSOaxrX-nYPrsRWQ2NBwLPWg&hl=en&sa=X&ved=2ahUKEwjy3fCRzfvwAhUL_KQKHUOwDTgQ6AEwB3oECAsQAw#v=onepage&q=A 230 V rated lamp used at 240 will achieve only 55% of its rated life&f=false


    I'm not sure I agree with some of the conclusions in any event.


       - Andy.


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    Alan S:

    Hello all, I wonder if someone can help me please?

    https://en.wikipedia.org/wiki/Voltage_optimisation#Overvoltage

    I'm trying to get a reference for a section in this wikipedia article to put in a report I'm writing but I can't find the original source. Under the "Common Power Quality Problems > Overvoltage" section there is a sentence that describes "A 230 V rated lamp used at 240 will achieve only 55% of its rated life". From the article I believe it is from the book "Commentary on IET Wiring Regulations 17th Edition" from 2016, ISBN 1849197652.


    I have tried to find it in a library as I don't have £90 to drop on a new copy of it, just to see if it is this book I should be referencing in my report, but I've had no luck there. Is there perhaps anyone with this book that knows whether or not the quote does indeed come from it or not?


    Any assistance with this query would be greatly appreciated.

    Thanks in advance

    Alan


    Since we've moved on from incandescent lamps and discharge lamps in favour of LED, is the statement still valid?


    In fact, with LED drivers outputting constant current, the situation is perhaps a little more complex:



    • Lower input voltage = more AC current = greater losses from volt-drop in the AC circuit supplying the driver

    • Raising voltage puts voltage stress on the "live side" (AC and rectified AC) of driver components

    • Lowering voltage puts more current stress on the "live side" driver components

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    Agree, non-filament lamps do not obey any such rule, and the thing that really affects the life of  LEDs is temperature, and the thing that kills switch mode supplies is spiky mains and rapid drop outs and restarts, rather than modest fluctuations. Certainly if the phrase remains it needs a note that it really applies to tungsten filament lamps rather than anything else.  Certainly any argument that a voltage optimiser saves you light bulbs is less solid than it was.


    I think 'moved on from' is a bit strong, I'd prefer 'moving on'  but I agree that new buildings are not being fitted with filament lamps and that trend is set to continue. It's a shame that the LED 'bulb replacements ' are very much designed to run hot and fail early, and therefore put electronics into landfill,  but it is an obvious commercial strategy to retain volume sales.

    Mike
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    I agree that wikipedia is an unreliable source of data about anything too complex or safety critical.


    However the fact that filament lamps are very sensitive to small changes in voltage is a well understood effect and data is available from a number of sources.

    Vacuum lamps, single coil gas filled lamps, coiled coil gas filled lamps, and halogen lamps all react slightly differently, but the differences between these are small.

    ANY type of tungsten lamp will have a short life at a higher than intended voltage. At a lower than intended voltage, life will be considerably extended but the light much reduced.


    When electricity is scarce or expensive, then a short lamp life is preferable. Electricity from disposable batteries costs about £150 per kwh ! or about ONE THOUSAND times the price of mains electricity. That is why torch bulbs are designed for a very short life, to make the best use of this very costly energy.


    In other cases, lamp replacement may be very costly in labour or plant hire. In such cases it is worth use of extreme long life tungsten lamps, the cost of the wasted energy being much cheaper than paying hundreds of pounds to change lamps atop tall structures or otherwise hard to access.


    Decades ago, I fitted 277 volt lamps on a 240 volt circuit, to greatly extend the lamp life.


    For most everyday applications, the standard 1000 hour life of a GLS lamp is a good compromise between life and efficiency.


    This is rapidly becoming of only historical interest as fluorescent, and more recently LED lamps take over the world.
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    This is rapidly becoming of only historical interest as fluorescent, and more recently LED lamps take over the world.


    Nice bright and hot tungsten lamps are valued by the occupants of terrariums, tropical fish tanks and tropical plants.


    What ever happened to heat lamps for aching muscles?

    Buy Heat Lamps | Infrared Heat Lamp Products | Cef | CEF


    How much?


    Z.


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    Filament lamps are rapidly going the way of gas lighting and oil lamps, both of which are still used today for specialist purposes, but are no longer mainstream illuminants for homes or workplaces.


    Lighting of tropical animals, the rearing of young farm animals, infra red treatment of aches and pains, oven lighting and the like are present day applications.


    Back in the good old days, GLS lamps came in DOZENS of different voltages, most of them in a choice of pearl or clear, a range of wattages, and choice of B22 or E27 bases.


    This catered not only for the multiplicity of supply voltages, but also enabled to the better informed user to over or under run lamps when there was a good reason for this.


    These days most vendors only offer 110/120 volt, and 240 volt.
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    Even if it's mentioned in a Wiring Regulations Commentary, it would be better (in your writing) to quote a source whose authors specifically know about lighting.  So Mike's suggestion (a lighting book) or Dave's (a manufacturer specification) sound preferable even if the quoted text can be found in the Commentary.


    If you're able to access this book (Handbook of advanced lighting technology) you'll find somewhere halfway down the introduction chapter the text  "The life of incandescent lamps varies inversely as the 13th power of the applied voltage.  Voltage 10 % below rated increases incandescent lamp life by a factor 3.5 over rated; 10 % above, a corresponding factor 3.5 reduction in life."


    Whether it's the "13th power" - or a bit more or less - depends on the particular lamp or the person you ask. This old article (The life-voltage exponent for tungsten lamps, Covington 1973) should be a very good source, but I can't access more than the first page. The exponent can also vary when moving away from rated voltage.

    The 55% of lifetime that you mention suggests instead an exponent more like 14, because:  1 / (240/230)^14 =~ 0.55. But it doesn't make much difference: with an exponent of 13 it's about 58% ...  it's anyway a big change in lifetime or light output, for not many percent in voltage.

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    a24ad164e8a5438cec84b38c363e826b-original-light_life_b.png

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    mapj1:
    a24ad164e8a5438cec84b38c363e826b-original-light_life_b.png

     


    Have you got the same info for a "coiled coil" filament lamp please Mike.


    Z.


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    not as another  graph, the indication in the text is that it is substantially the same, with the efficiency curve moved up a bit, so less watts for the same lumens,but the same trends.


    I;d expect quartz halogen to have a slightly different slope on the life curve however, as the filament evaporates and self repairs to a degree.

    Mike.

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