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Old 23rd Apr 2019, 6:59 pm   #21
The Philpott
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Default Re: The lightbulb conspiracy

I couldn't fathom why they were marked as coiled coil rather than supercoil. I remember 15w and 25w GLS lamps as being particularly pathetic regarding minor mechanical shocks.

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Old 23rd Apr 2019, 7:08 pm   #22
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Must admit Dave I have never heard the term 'Supercoil' but I'm surprised it was not taken up by a leading lamp maker. The 15 and 25w lamps were always single coil, often a long filament strung between spider supports.
They were delicate. The best ones were manufactured for the hood lamp on the Hoover vacuum cleaners. They were very rough service! J.
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Old 23rd Apr 2019, 11:45 pm   #23
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Default Re: The lightbulb conspiracy

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It was repeated ad infinitum in the 'eighties as a sort of 'did you know' story, that 1000hr domestic lamp life was enforced by an industry cartel and better lamps vis-a-vis life AND lumens could be made if they wanted to make them.
The rumoured better ones were probably halogen lamps and they were in fact marketed already in the 1980's even though they may not have sold too well for home use and drop in halogen replacements for traditional bulbs came much later. I remember reading about extensive research on the then new technology in Philips technical reviews from the (I think) 1960's.
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Old 24th Apr 2019, 1:02 am   #24
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Default Re: The lightbulb conspiracy

No personal experience of lamp manufacture, but after GEC got out of the GLS lamp business I acquired a number of textbooks relating to electric lighting that were no longer required.

The existence of the lamp cartel was no secret.

The origin and development of the cartel is discussed in some depth in "The Electric Lamp Industry", (Bright), published in 1949 for MIT. Rather than seeking to shorten lamp life, the first cartel was established in Germany around 1903 with the objective of allowing the manufacturers to make enough profit to make lamps of good quality. Unlike the US and the UK, where the patentees could impose prices and quality control, there was no effective patent protection for lamps in Germany, resulting in savage price-cutting that resulted in lamps of poor quality and short life. At this date, the only known metal to make a reliable gas-tight seal was Platinum, and cheaper lamps often used iron wire that failed due to leakage.

Edison's original lamps lasted around 2000 - 3000 hours, but the light output soon fell to 80% of its initial value. Life was reduced to 1000 hours circa 1880 to improve luminous efficiency. Improvement in gas mantles in the 1890's gave gas a temporary superiority, meaning that Edison had to run his lamps even hotter to compete, thereby shortening their life to around 600 hours.

A detailed numerical analysis, including financial costings, of the relationship between lamp life, luminous efficiency, and cost of electricity, is set out in Westinghouse's "General Illumination Course" workbook of 1931. The 1000-hour life is presented as being a reasonable trade-off between lamp life and electricity cost for a given level of illumination for domestic users. Under-running a lamp certainly increases life, but reduces light output, leading to an overall increase in the cost per lumen. Over-running a lamp is actually slightly more economical in terms of cost per lumen.

Some extracts from these books are attached.

The conspiracy theory proponents do seem to ignore the practicalities of GLS technology and the cost of electricity. Until they moved house in the 1960's, my parents benefitted from a pre-nationalisation contract with the electricity board whereby 10/6d a year covered any maintenance needed on the installation, including free replacement of bulbs. I always wondered as a child why people paid money for bulbs when all we had to do was take the old bulbs into the electricity showroom and they would give us a replacement. No incentive for them to supply bulbs of short life. AFAIR, 2000 hour lamps were available in the 1970's. I did try a couple, but they certainly produced less light that the ordinary GLS versions.
Attached Files
File Type: pdf Bright 1949.pdf (1.52 MB, 21 views)
File Type: pdf westinghouse 1931.pdf (540.7 KB, 18 views)

Last edited by emeritus; 24th Apr 2019 at 1:20 am.
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Old 24th Apr 2019, 9:59 am   #25
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Default Re: The lightbulb conspiracy

A manager in a small shop in Wigan (1960)S) kept close control on overheads, they used standard light bulbs for many areas of the shop. We knew him well and he asked us to get in a supply of 60w lamps from various UK makers.
A few months later came and asked us to supply lamps by Crompton, I think that was the brand, he found on average he got the 1000 hours out of those, the other makes lasted considerably less in his installation.

One installation doesn’t make good statistics but he was convinced about the outcome, sensible man so no reason to doubt his findings.
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Old 24th Apr 2019, 2:55 pm   #26
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Default Re: The lightbulb conspiracy

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Rather than seeking to shorten lamp life, the first cartel was established in Germany around 1903 with the objective of allowing the manufacturers to make enough profit to make lamps of good quality. Unlike the US and the UK, where the patentees could impose prices and quality control, there was no effective patent protection for lamps in Germany, resulting in savage price-cutting that resulted in lamps of poor quality and short life. .
"Cheap lamp-bulbs" were also commonplace in pre-WWII Poland: I remember a distant relative once saying that they had door-to-door sellers of cheap bulbs (and dusters and candles and boxes of matches and bars of soap) in the same way as the beret-wearing Frenchmen cycled around selling onions.
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Old 24th Apr 2019, 7:11 pm   #27
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A few months later came and asked us to supply lamps by Crompton, I think that was the brand, he found on average he got the 1000 hours out of those, the other makes lasted considerably less in his installation.
Absolutely! I stocked just about every make of quality lamps available. My shop was noted for it.

I used to stock Crompton [Parkinson?] /Hawker lamps insisted by some of my customers. They definitely were a high Quality lamp well respected in the trade, supplied to schools, local authorities and industry.

I think they sold their lamp business to Philips, another high quality lamp manufacturer.

Lamps were the bargain purchase of the 20th Century. A standard quality lamp retailed for around 1/8d in 1964, about 8P today.

Speaking of good quality lamps we must not forget our old friend F. W. Woolworth and Co. They marketed VESTA and SUNSHINE lamps, all single coil and they had an excellent reputation, sold from their fascinating electrical counters with it's chrome fittings, yards of Ever Ready and Vidor batteries, torches, and a million types of plugs and lamp adapters. Heaven to a 7 year old that would keep me quiet until Mum finished her shopping. [Woolworth's Wimbledon store] Regards, John.
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Old 24th Apr 2019, 9:30 pm   #28
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Must admit Dave I have never heard the term 'Supercoil' but I'm surprised it was not taken up by a leading lamp maker. The 15 and 25w lamps were always single coil, often a long filament strung between spider supports.
They were delicate. The best ones were manufactured for the hood lamp on the Hoover vacuum cleaners. They were very rough service! J.
I wonder if "Rough service" for lightbulbs was ever quantified into a formal specification, of G-forces and numbers-of-applications-before-failure?

The cooking-compartment bulb in my Sharp microwave has had a history of repeated failure - I'm thinking that the shocks from 20 or 30 door-shuttings per day can't have helped. For the last half-decade I've given up replacing the bulb because extracting the oven from its built-in-kitchen home, removing the case, swapping the bulb, reassembling and refiting it into its home is just too much faff.

Thought: given that a typical microwave-oven is slinging 800-1000 Watts of microwave-energy around, a clued-up designer could surely produce a cooking-compartment-illuminator using a 1/2-wave dipole and a bunch of neons or LEDs across the feedpoint to provide the necessary "Cooking-in-progress" reassuring glow?
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Old 24th Apr 2019, 10:38 pm   #29
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To Ward's the end of the GLS era, Woolworths were the only brand I could find that fitted fast-acting ballotini internal fuses rather than simple fuse wire. Unlike simple fuses, the ballotini fuses would blow before a 6A MCB tripped. I never understood why Woolworths never promoted the superior qualities of their bulbs, only mentioning it in small print on their cartons.
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Old 25th Apr 2019, 9:32 am   #30
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What was the reason for the 'pink' coloured glass support spider in certain low wattage lamps typically 15 and 25W? Always a mystery to me. John.
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Old 26th Apr 2019, 10:29 am   #31
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Default Re: The lightbulb conspiracy

This is an excellent thread, and a fine illustration of the depth of knowledge available via contributors on this forum!

I can only add that the term "Cartel" is perhaps a little harsh: in this instance, it appears that the industry were attempting to impose a defacto standard in the absence of a BS ? In fact, is there no British Standard for light bulbs?

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Old 26th Apr 2019, 11:57 am   #32
Martin G7MRV
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I used to stock Crompton [Parkinson?] /Hawker lamps insisted by some of my customers. They definitely were a high Quality lamp well respected in the trade, supplied to schools, local authorities and industry.
Just an aside -

Crompton-Parkinson. Part of Brooke-Crompton-Parkinson/Hawker-Siddely group, and later Tyco. Manufactured lightbulbs and luminaires at their Wheatley Plant in Doncaster. My home town and I worked their for a short time during school holidays. Like most of the heavy industry in that location, now gone, replaced by 5-a-side pitches! This part of Doncaster, along with my village Kirk Sandall (next along) was very tight-knit around a few key factories. You either worked for 'Cromps', 'Harvesters' (international harvesters, later Case Ltd) across the road, Rockware glass (most of my family) or 'Pilks' (Pilkingtons). And every factory had a social club!
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Old 26th Apr 2019, 11:59 am   #33
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Default Re: The lightbulb conspiracy

BSI for tungsten filament lamps for domestic use.
https://shop.bsigroup.com/ProductDet...00000030189879

Donít click on the buy link.
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Old 26th Apr 2019, 1:00 pm   #34
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Probably about 1990 ish I used to do electrical work in a hotel . I believe I’m correct in the name but they went through a phase of trying a new type of lamp made by Litronics .they were a traditional fillament lamp but had a life span of I think it was 16000 hours .they bought loads especially candle lamps. They soon got replaced well before there time was up due to the poor light output even though the watage was the same the light output was not. I still have one hanging around somewhere Andy
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Old 26th Apr 2019, 2:45 pm   #35
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Default Re: The lightbulb conspiracy

I did wonder if filament life was set by makers adhering to the Mazda design spec:

https://en.wikipedia.org/wiki/Mazda_(light_bulb)
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Old 26th Apr 2019, 6:50 pm   #36
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Well this is how it started and these examples from my collection have probably survived more than 1000 hrs!

Pictures 1&2. Very early carbon filament top pip evacuation [1905?]

3. GEC. They must have borrowed the glass bulbs from the valve
dept..

4 A later drawn wire cage filament. [1930's?]


5 An early drawn wire cage filament. 'Royal Ediswan' [1930's?]

Lamps run on much reduced voltage to allow photography of filaments [40-50v]

Enjoy, John.
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Old 26th Apr 2019, 6:59 pm   #37
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Another picture of the Royal Ediswan cage. Running on around 20V the pink glass support 'flag pole' can be seen in the centre. J.
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Old 26th Apr 2019, 7:14 pm   #38
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Default Re: The lightbulb conspiracy

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What was the reason for the 'pink' coloured glass support spider in certain low wattage lamps typically 15 and 25W? Always a mystery to me. John.
There was a historic code for the coloured-blobs on the supports for low-powered filament bulbs; this was associated with the US convention to identify bulbs as '#47' and the like.

If anyone's interested, I can post the colour-blob-to-specification tables from a couple of WWII-era US documents.
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Old 26th Apr 2019, 7:45 pm   #39
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Default Re: The lightbulb conspiracy

Nice vintage lamps there!

I especially like the valve-shaped one. There used to be other shapes too - the mushroom bulb was one I remember. The squirrel-cage filament bulbs are still on sale. Pound shops occasionally have some. I bought a few last year from Poundworld when they were closing down, reduced to 45p / 30p. They don't give out much light, though. And one of them blew a 3 amp fuse immediately when I switched it on. I actually took the faulty bulb back to Poundworld, who gave me a new one without question, which was very nice of them. Years ago, the electrical shops had a live lampholder by the till. When you bought a bulb, the shop assistant plugged it in to show you it lit up. After that there were no comebacks.

Another advert I remember from the 70s or 80s - Mazda Doublelife bulbs - "Double the life but not double the cost". They claimed a 2000 hour lifetime. Around 1990 I got one of those Innovations catalogues through the post. It offered a 10,000 hour life filament bulb, but expensive (£10?), and they admitted it didn't give out as much light. So it was certainly possible to make longer-lasting bulbs. I guess 1000 hours was a compromise between lamp life, light output and profit for the manufacturers. Longer-lasting bulbs = fewer sales and less profit, or a higher unit price must be charged. Too short a life = dissatisfied customers who may be tempted by a competitior's longer-lasting products.

Presumably 1000 hours life for a lightbulb that cost a few pence is what most customers were happy with. When compact fluorescent bulbs first appeared, they were not popular even though they lasted longer and used less electricity. People thought they cost too much to buy. It was only when they were virtually given away by government subsidy, and filament bulbs were banned, that people changed their habits.

Nowadays, the lifespan of TVs and electrical goods is much shorter than of old, but they are cheaper to buy in real terms. Customers seem to have accepted this. It suits manufacturers better. More replacements sold = better cashflow and high volume manufacturing achieves better economies of scale.

Long ago (around 1991) I saw a story on an American TV news programme (ABC or CBS news). General Electric USA had taken over the Tungsram lightbulb factory in Hungary after the fall of communism. People then started to notice that they had to replace their lightbulbs more often. "Welcome to capitalism" was the headline.
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Old 26th Apr 2019, 8:06 pm   #40
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When compact fluorescent bulbs first appeared, they were not popular even though they lasted longer and used less electricity. People thought they cost too much to buy. It was only when they were virtually given away by government subsidy, and filament bulbs were banned, that people changed their habits..
First/Second-generation CFLs were truly horrid: they were slow-to-start [a real pain if you need to switch on the light at the top of the stairs and then want to walk down to the toilet without waiting a minute for the CFL to struggle-towards-full-brightness]. They were also invariably "Dim White" colour-spectrum - which lit everything with a horrid sub-candlelight-yellow meaning everyone illuminated by such monstrosities appeared to have Jaundice.

The utility-companies were happy to push these horrors onto their customers because they could claim-back the cost from some obscure-but-Taxpayer-supported 'eco'-fund.

They were truly unpopular - both with their target-victims and with us utility-company investors. Holding-back a decade, by which time LEDs had become the only sensible energy-efficiency option, would have made far greater economic- and environmental-sense.

[I have a personal theory that a proportion of the recent mental-illness/depression thing is due to exposure to poor artifiical-light-spectrum; if you live your life in gloomy-light your mindset will become gloomy! I'm certainly much more upbeat since I fitted-out my house with 6500K LEDs delivering 800-1200Lux light-levels everywhere [and 2500Lux in work-focussed spaces].
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