Hi.

My friend give me small bunch of used T12 fluorescent lamps, most of them manufactured by Airam. He said he found them in basement of building where he works. They were cleaning basement and find theese in boiler room. Now do anybody know when theese were manufactured?

Here is a philips made TL 40W/34 Deluxe. You can see small print 5E in bottom right. Is that manufacturing date code? I think this Deluxe color temp is weird. I like more regular collwhite

http://www.lighting-gallery.net/gallery/displayimage.php?album=lastup&cat=0&pos=1

Here is one made by Thorn. there were only couple of theese. All others are 40W but theese are 65W

http://www.lighting-gallery.net/gallery/displayimage.php?album=lastup&cat=0&pos=2

And lastly some Airam made. I think Airam is not so famous manufacturer in wold. But in here Finland its most famous. I dont know if there is any other Finnish one. So probably you can't me help to date theese one. But they probably are same age as those Thorn/philips lamps.

http://www.lighting-gallery.net/gallery/displayimage.php?album=lastup&cat=0&pos=0

A bit late but here's my reply:

Philips date code 5E stands for May 1975 or May 1995. Since TL40W/34 De Luxe lamps were discontinued at the end of the 70s, this lamp is from May 1975.

The "De Luxe" suffix was used for lamp with higher color rendering indices (CRI in 80s, 90s). Color 34 is the predecessor of modern colour 940 (CRI>90, CTT=4000K). Other examples are 32 De Luxe (nowadays 930), 27 De Luxe (current 927).

4000K Coolwhite lamps (old color 33, current 540) have medicre CRI (50s or 60s) so the suffix De Luxe does not apply here.

Lampwizard