Obsolete fluorescent light fittings

[Rhgbristol]

The very earliest commercial fluorescent lights were indeed the T12 80w lamp, based on this rating I recall, due to the common availability of the 80w chokes for Mercury vapour street light lamps (later known as mbfu). The lamps stated appearing in the early 1940s.
These were invariably bc capped.

Other sizes then appeared, notably 2' 6' and 8' - although I have never seen bc capped versions of these sizes. They were all bi-pin capped.

The 5' lamp then dropped to its dual rating of 65/80w enabling the same lamp to work in older and newer circuits. This common size was around from the 1960s right through to the early 1980s, when the t8 slimline ranges appeared - the 5 ' then being 58w.

As it others have pointed out, the t8 lamps did not like the switch less start (quick start / SRS) ballasts, due i believe to a different strike voltage coupled to the krypton gas filling that the t8 lamps used.

I learnt this to my cost, when working as an electrician in the 80s relamping a school hall, with scaffold towers out and the like, and our boss bringing me a box of the new t8 lamps to fit into the previously t12 lamped fittings.

A call to Thorn's technical help line, and a return to the wholesalers then sorted it!

By about the early to mid 90s the t5 tubes appeared, all run on electronic gear, and completely incompatible with the early ranges in terms of physical size and ratings.

All very efficient, but those electronic ballasts, just do not seem to last like the older wire wound gear.

'Built in obsolescence' as my elderly dad would say.

Welcome to the real world as I say.....

Give me a 1970s t12 fluorescent any day - it will go on forever - lamp availability permitting!!

[Brigham]

The 8' size was certainly BC at first. The other sizes were post-war, and had the new 'bi-pin' cap.

[Zelandeth]

Correct, the BC caps initially being used because it would have been unacceptable to divert the resources to introducing a new lamp cap and holder during the war effort. So the existing caps were used.

Seem to recall that BC lamps were still being produced for replacement purposes until 1985 or thereabouts.

In answer to the question about the 36WT8/40WT12 tube compatibility, provided that the fitting has a starter (or electronic ballast), the 36W tube should be fine. If there is no starter (i.e. it's a Quickstart or SRS ballast) you will find that the T8 tube will struggle to strike, so you'll need to use the 40W one.

Stocking up here as I've got a huge number of Quickstart 40W ballasts in use in our garage, and T12 lamps are getting progressively harder to source these days.

[russell_w_b]

When I worked at British Steel in the 1970s we used to re-lamp the original wartime fluorescent fittings, the ones that had a starter lamp with a bakelite cap and the end resembling the end of a test-tube.

BC tubes were increasingly difficult to come by, but there were adaptors available to convert bi-pin to BC.

[whyperion]

Mum reminds me when she worked at a lamp factory during the war , an American company rented part of the works for (?production)/ storage of parts for fluorescent tubes one of her friends knew more of what/how was produced (in London) as mum stayed on the incandescent ranges of bulbs.

Meanwhile the badged 36w external had a claimed Fitzgerald 40w ballast actually inside beneath the metal covering, however the T12 40w tube had strobing effect and would not properly strike, so that tube is back in the kitchen fitting ( which has stopped humming ), despite not working in that fitting 2 years back !, and the replacement 36w T8 tube is happly shedding light in the garage, it takes a short while to fire up but is constant and quiet thereafter. That just leaves one more combination to double check but should work, I'll report if it does not. Next I am after some 2ft tubes, as the latest skip find has no tube and I don't want to buy one if the fitment is unserviceable.

[emeritus]

2' tubes come in 20W and 40W versions, as noted in various earlier posts ( eg #86, #127 and #142)

[hannahs radios]

I have just finished getting a 2 foot Fitzgerald flouro lamp going again, it was rather dirty and the choke is a bit rusty. Unfortunately I can't get the starter out of its holder anyone know how I can do this? It does still work so not very urgent. Secondly I put a current clamp on it to look at the current waveform and surprisingly it's very clean even at zero crossover. I expected to see a little current kick, but just looks like a clean crossover. Has anyone else seen this?

[emeritus]

We have two vintage 2' fittings with Snapstart ballasts that normally work well, but with the drop in temperature, they have sometimes been reluctant to start when the central heating has not been on. Ditto for a more recent starter-equipped 2' fitting in the garden shed. I tried cleaning the tubes to no avail, but then remembered reading in a 1950's reference book that fluorescent lamps for use in Europe were generally coated with a silicone to ensure they started in the damper European climate, whereas lamps for the US market were not. I don't know if the current production are silicone treated, but thought I would see if applying some silicone furniture polish would improve matters.

First problem, where do you find silicone furniture polish these days? I used to keep a tin of what was explicitly stated to be silicone polish, for lubricating my plastic curtain rails, but have used up my last tin. Most of the products in my local supermarket now proudly announce that they are silicone-free (and can therefore be used on natural wood). I did eventually find an aerosol can of basic polish (~50p) in my local Wilkinsons that, while not stating it was silicone-based, did say it was not suitable for natural wood, so I thought it was worth a try. It does seem to have done the trick, as even the fitting in the shed that I gave up using in damp winter now strikes without fuss.

[broadgage]

Originally Posted by hannahs radios

I have just finished getting a 2 foot Fitzgerald flouro lamp going again, it was rather dirty and the choke is a bit rusty. Unfortunately I can't get the starter out of its holder anyone know how I can do this? It does still work so not very urgent. Secondly I put a current clamp on it to look at the current waveform and surprisingly it's very clean even at zero crossover. I expected to see a little current kick, but just looks like a clean crossover. Has anyone else seen this?

It is possible that the old starter has overheated, partially melted and thereby stuck into the holder. Brute force should work for removal though you may need to replace the starter holder afterwards.
Alternatively disconnect the old starter holder but leave it in place to preserve the original look.
Fit a new holder and starter internally.

The current waveform drawn by a fluorescent lamp is very dependant on both the age and the length of the lamp.
Shorter lamps typically work at lower voltages and therefore "turn on" earlier in each cycle of the mains supply, and do so more gently.
Longer lamps run at higher voltages and therefore do not "turn on" until later in the sine wave. With current flowing only for a short part of each mains cycle, the peak current has to relatively substantial, and the "turn on" relatively sharp.

Lamp age is also relevant, a well used but still functional lamp tends to a very sharp "turn on" that can produce significant RFI.
IF RFI from a fluorescent light is excessive, then I always urge trying a new lamp before looking for anything more complex.

[hannahs radios]

Thanks. If and when the old starter gives up I will probably incorporate a new one in the fitting and leave the old to, as you say. preserve its look. It's a bit noisy especially on 14 Mc/s, but not so bad to make me want to change it. After all it's only a project it won't live in the radio shack.

[mole42uk]

Mention of the Netaline fluorescent lamp reminds me that I have three which I plan on restoring next year. They were all working when removed, so it shouldn't be too daunting a task. Did they use a special tube?

[Lloyd 1985]

I found a Mazda Netaline fluorescent fitting recently, dumped outside a derelict pub in Leamington spa! It was quite rusty, someone had bent it, and the cap off the end that covers the tube connector was missing (not the plastic cover for the starter) as well as the bit of pipe that it attaches to the ceiling with.

I set about bending it back as straight as possible, sanded it down and re-sprayed it. I found that the resistance wire was O/C, I found the break and repaired it with a crimp, fitted a tube and connected it to one of those 12v to 230v inverters (looked a bit scary plugging it into the mains!), it fired up just fine with a T8 4ft tube. Now just need to find the remaining parts, or make them! Oh, and polish up the plastic cover part too...

I also have a couple of old GEC fittings, both recovered from my Grandad's derelict shed. They both needed stripping and repainting too. One is 5ft and the other 2ft. I was going to convert them to 24V operation to use with the solar panels on the workshop, but decided against it as I quite liked the loud buzz when you turn them on!

Regards,
Lloyd

[Zelandeth]

T8 tubes won't work reliably in a Netaline due to the resistive ballast.

You *may* get them to strike if you're lucky, living in a higher voltage mains area and/or have a slightly lower voltage tube. However they really need a T12 tube to work reliably - if you run one regularly (like I do), worth keeping a stock of tubes as manufacture/import of T12 tubes into the EU has now been banned, so once the current stocks are exhausted, that's it.

[mole42uk]

Originally Posted by Zelandeth

T8 tubes won't work reliably in a Netaline due to the resistive ballast.

Thanks! That's exactly the information I needed.

[Zelandeth]

Glad to be of help!

Luckily 4' T12 tubes were one of the most common types so they've not become too hard to find yet. Let me know if you get stuck and I'm sure we could arrange a couple to be sent your way. Independent electrical outlets, especially smaller ones are likely to still have some on the shelf too. It's worth fitting an electronic pulse starter to these fittings as that makes starting of the lamps far kinder and can drastically improve the life of the lamps if they are switched on and off a lot.

The other solution would be to re-wire the fitting with a small high frequency ballast in the starter compartment (I've seen ballasts small enough) which will then allow the 36W T8 tubes to be used.

A T8 tube looks daft in a Netaline though, so I would probably use a dead T12 tube to create a "sleeve" to hide the T8 tube in.

Do bear in mind if doing any wiring work on these that the resistive ballast wire is asbestos sheathed, so if it's to be disturbed, work outdoors and take appropriate precautions. It should not cause any issues if left alone though as it's quite well packaged. I've got a completely original one here in daily use which I don't worry about.

Not sure how long the Netaline was made, but it seems that "early" and "late" units can be told apart by the fact that the starter covers changed at some point from metal to plastic.

[mole42uk]

Mine have metal covers, it's unfortunate that the PO brush painted them though :-( Good idea about putting proper starters in.

The local electrical wholesalers have 4' T12s in stock. They seemed quite grateful when I said I would buy some.

I have experience of asbestos insulation for heater wiring - in old pottery kilns - and the house has asbestos ceilings which is nothing to worry about so long as I don't start hacking it about!

[spamfritter]

Originally Posted by emeritus

First problem, where do you find silicone furniture polish these days?

Don't know about silicone furniture polish, but Lakeland do a small bottle with a dropper spout on it of a liquid that does the same job called Free"n"easy. Bar code number 20089986. Domestic management brought it to do the curtain rail job and it works well.

[Zelandeth]

Not sure about furniture polish, but last time I needed to do a similar job (I run some old Atlas fluorescent fittings with Quick Start gear which can be similarly picky about starting), I used Autoglym Ultra Deep Shine car wax. Can't remember if it's silicone based or not, but it's massively hydrophobic and presents a barrier to surface contamination, which is the general idea.

It's expensive stuff at fifteen quid or so a bottle but it goes a really long way - and I always have it in stock for the cars anyway!

[markrichieholde]

I'm interested in old fluorescent light fittings, especially the Thorn pop pack that was back in the 1970s. The fittings that use to be atlas badged, and for some strange reason they had a green spine. They were far superior to the ones Thorn make now.

I have one in my garage roof and it works perfectly, and looks almost new.

[trobbins]

The 'modern' mains frequency chokes associated with 20-40W tubes are excellent for recycling in to amplifiers and power supplies. With a 240VAC supply, the 36/40W tube uses about 2H inductance, which can easily handle half an amp DC in a power supply filter. I seem to have plenty of the 36-40W chokes, but am on the lookout for 18-20W chokes as they will have a higher inductance to drop the same voltage with a lower current.

http://dalmura.com.au/projects/Choke%20measurement.pdf