Fluorescent Fitting. How Long Has This Been Going On?

The ones with the bayonet lampholder on the ends instead of bi-pin. So I guess 1950s. Had to fit bi-pin connectors to allow a replacement modern  tube to fit.

In the workshop at my Uncles, in a little used corner, are a couple of 5' trough type fittings. These still have ATLAS 80W tubes that have bayonet end caps. One has a 4 pin starter & other other has a starter that is similar in shape to a pygmy lamp - it has a SBC base & contains a set of contacts much like a modern glow starter. Both of these fittings have huge iron chokes & still work.


The workshop dates from WWII when the building was a Fire Station so these fittings may well be original. Another fitting is an early two-tone thorn fitting still with an ATLAS bi-pin tube. I believe this fitting dates from mid/late 1960s.


There are also a couple of 40W filament lamps around marked "property of the War Dept". Unfortunately they no longer work.

For those who have not seen them.


there cannot be many left - I do remember being told to beware of beryllium oxide   in some early tubes and not to break them. Not sure how real that risk actually is though.

Leaving aside those antique bayonet lamps, is there any form of date code on the tubes, which would allow us to date them?

In my mates shop in town he has an ancient cryselco fitting the tube in it looks ancient too as does most of the wiring in there

I have seen immediate post war fluorescent light fittings still in use fairly recently.

5 foot, 80 watt lamps, bayonet cap lamps, choke tapped for different mains voltages. Separate starting transformer. These transformer start circuits wont work a modern lamp.


I have seen fittings with no choke, a special filament lamp being wired in series with the tube. These special ballast lamps are no longer manufactured AFAIK.


I also recall special coloured fluorescent lamps that were a different colour each end. Obtained by different phosphor coatings not by a colour filter. They came in three different colours. Pink/blue, pink/green, and blue/green. Popular for street lighting in seaside resorts.

broadgage:


I have seen fittings with no choke, a special filament lamp being wired in series with the tube. These special ballast lamps are no longer manufactured AFAIK.

 

I seem to recall these also needed special tube. Although the filament lamp can act as a current limiter once the tube is running, it obviously can't give any inductive 'kick' to get the arc started so another mechanism is needed.

I seem to recall these also needed special tube.

That sounds familiar - an earth 'stripe' along the length of the tube perhaps?

   - Andy.

The fluorescent fittings with a tungsten ballast lamp would usually start any lamp that would also start from a leakage transformer circuit, a semi resonant circuit, or from a transformer start circuit. They would not reliably start lamps intended for switch start fittings.

Earthed metal close to the lamp helped.

For non earthed lighting circuits, "artificial earth" units used to be available, these consisted a small 500 volt capacitor to be connected between mains neutral and the metal fitting. In premises previously equipped with gas lights and with the gas pipes still in place, a bit of wire between the metal fitting and the gas pipe also worked.