The Lamp Room

Come to say it is surprising that I ran into 15W T8 tubes at the car boot (the GE and Sylvania made ones)

I think they are used for some old signlights that used T8 tubes??

Some internally illuminated sign lights use 15w T8, but it's one of those tubes that's not really very common. Other than that, place you were most likely to see it was in under-shelf link lights, but most of those have been replaced for T5 / T4 / LED over the years. I've got an old MK shaver light that takes a 15w T8 too. Probably the size of tube I've installed the least of in my career to date!

I’ve seen them used in ceiling lights with diffusers

I knew it would have a purpose mainly for illuminated roadsigns and signlights! It be rare to see linklight cabinet fixtures use T8 15W because of T5 and sadly LED

Otherwise it is a uncommon rare type of tube, a T8 15W one! No wonder I made mistake thinking they were 18W!!! Pity that makes them shorter that I cannot light them up

Ah, purchased some in error then have you?

At car boot sale yes! Sometimes an error purchase can turn out to be a cool find!

They were used many moons ago to illuminate the hob of electric cookers too. (showing my age now)

15 watt T8 is common as muck here as use in Desk lighting in the US