BulbCollector Forums
BULB DISCUSSION BOARDS => Modern Electric Lighting => Topic started by: Zelandeth on October 09, 2005, 06:42:01 pm
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Right, so far I've been using 100% guesswork when dating most of my lamps - this is something I would like to change!
Is there anywhere that I would be able to find lists of the date codes used by at least the major manufacturers?
Most (all at present) of the items I deal with are >1980, so I'm not going back into the depths of history, but it would be really nice to be able to actually put down when things were made without having to ask someone every time!
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Date codes are, for some reason, usually a closely guarded secret among most lamp manufacturers. They range from the fairly simple through the horribly convoluted to the just plain vague. Dots, dashes, odd symbols, letter and number conbinations that change around every now and then, all sorts. Anything to keep the date of manufacture from anyone but the manufacturers themselves. One theory suggests buyers might not accept lamps sold as new that they know actually to be old stock. As many don`t have a "sell-by date" (the fact that we as a nation are still widely using 1930s incandescent technology is testament to that) in some cases specialist or obscure lamps could sit on suppliers shelves for many years - my local lighting shop found me some from the 70s deep in storage. Coding them means there is no obvious made-by date to customers, while still allowing the manufacturers to keep track of production runs in case of recalls or warranty isses.
I do have some date code info for Philips, Osram and some others that I got courtesy of one mr. James H, but I got it on the condition that I treat it all as being highly classified and not go publishing anything anywhere. You might like to ask JDH directly if there`s anything he can disclose, as he`s nice like that.
:)
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UK Osram used a fairly simplistic date code in the 1960s-1990s which could be considered in the public domain if you collected enough lamps to crack it. Any lamps with a simple two-letter code, made in the UK began with A (1945, 1969), B(1946, 1970), C(1947, 1971) and so on for the first letter, and the month (A-M, skipping the letter "I") is the second digit.
The dots and dashes on other manufacturer's are far more difficult to explain, and this is maybe not the forum but in almost all the dotted systems of the "west" I have seen, the dots count down month by month, and year by year, and a good helper would be to collect enough lamps to find the minimum and maximum no. of dots in each group. You'll usually find one group with between one and six dots that can only be the month (where a dash gives you the "other six") and the other group would vary between one and five for the "year".
Some Japanese lamps have one row of 1-5 for the year and between eleven and zero dots for the month.
Philips' was the first code I worked out as a 14-year old collector in 1979, where the month is a letter (A-M) and the last digit of the year is next to it. Alternating decades give you a 20-year code so that, say, A5 would be January 1965, 1985 and 2005, whereas 4C would be March 1974 and 1994.
If you have a lamp that I could possibly help date for you please mail ladnewton@hotmail.com, and enter codeword "LAMPDATE" somewhere in the subject field so as to keep it out of my junkmail folder.
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Figures...knew they'd not be as simple as I thought!
Thanks for the info though! The Philips data appears to work well, just gone through most of my Philips lamps, and the dates I've got all sound reasonable. Though I've got a couple without codes on, one of which does have a Pi symbol...not sure if that's something to do with date coding.
Haven't managed to make any sense of the Osram ones I have though - partly because the two older SOX lamps I own have lost their markings, and the newer one has the code VB (At least I assume that's the code!)
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The SOX coded VB was made in February 1964 or February 1988 most likely. Any Osram lamps newer than 1990 (HID, fluorescent or CFL) made by Osram GMBH (as opposed to UK GEC) will have the seemingly randomised German Osram year letter code in which three letters (two letters and a number between 1980 and 1994) appear. First letter (lower case) is the factory identifier. 2nd letter (lower case=1st 6 months; UPPER CASE=2nd 6 months) is the year ID, and the 3rd element is (x,y,z, X,Y,Z) OR (R,S,T,U,V,W) for Jan-June and again July-December, and from 1980 the month is simply represented by 1,2,3,4,5,6 for the six months in each half-year.
Year Letters
1960,1980= m
1961,1981= r
1962,1982= u
1963,1983= n
1964,1984= b
1965,1985= d
1966,1986= t
1967,1987= h
1968,1988= a
1969,1989= w
1970,1990= x
1971,1991= z
1972,1992= y
1973= v
1974,1993=e (no explanation offered!!!)
1975= g
1976= p
1977= k
1978= f
1979= s
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1988 you say...
Now ain't that a coincidence...look what I found stuck on the back of the ballast...
(http://zelandeth.artamir.org/lamps/na/lp/supersox18/testdate.jpg)
Nice work!
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Cool.
I always thought the slightly mysterious nature of these codes made them more fun to solve but nowadays the likes of Philips and GE (particularly on straight, 2D and some CFL fluorescent types) use clear dating (e.g. 20.10.05) suggesting there was never any need for all the secrecy in the first place!
Any other items you need dating, I should probably be able to assist.
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Many British lamps also use the ELMA date code, established by the Electric Lamp Manufacturers Association in May 1934. It began with code 05, and increased by one digit per month, until reaching 96, when it reset to 01 and repeated the cycle. This was used on all British Philips lamps up to 1963. All Osram-GEC lamps used this code until December 1957 when it was replaced by the code Lee indicates above. Mazda/Thorn/GE lamps were made with this code right up to the present day, except for high volume incandescent and fluorescent types, which each have their own dot/dash system. CFL from Enfield have an apparently similar code but their system runs on a cycle 24 months behind the rest.
Best regards,
James
James