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PostPosted: Mon Dec 31, 2012 12:27 am 
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I have heard mention on here a couple of times about bayonet end-cap flourescent fittings and tubes.
Not sure if this is the right sub-forum to start a discussion on them, but I have two Crompton BC end-cap fittings in my collection, pictured below.
I wondered if anyone could date them for me, and thought I would show pictures for anyone interested.

One is an all-pressed-steel construction, and the lamp starter is a small green glass bulb which has a small bayonet fitting to it. The only thing missing are the two covers which go on the end of the tube, to cover the lampholders. I presume this fitting works, but I have never switched it on. I salvaged it about 17 years ago from a factory, it was in the roof above where the offices had been built and had been disconnected.

The other is a steel body and white perspex diffuser, the starter is an aluminium can with (I think) a 4-pin base on it. It was salvaged about 6 years ago from a domestic garage I cleared for someone I worked with, before the garage was demolished.Again, I presume it works but am not sure as the power had already been disconnected from the building before I cleared it.

I also have (but not pictured) an AEI battern fitting which needs restoring but is complete. This was installed in 1961, and removed from service march last year when the tube failed. This lamp had lit approximately 6 hours per day, every single day, from when it was installed and never had a replacement tube. That is a staggering 51 YEARS service. It took some time to explain to the old chap whose house the light was in that you cant get BC tubes anymore!
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crompton bc lamps.JPG
crompton bc lamps.JPG [ 43.49 KiB | Viewed 14636 times ]


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PostPosted: Mon Dec 31, 2012 2:02 am 
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You got yourself a couple of relics there! The best people to date such items on here are likely to be Claire and Simon C, but personally I'd give a rough estimate that those are very early 60's fittings.

The starters will indeed be 4-pin... two contacts simply have a bimetallic strip connected to them, which is parallel to the tube - the other two contacts go to a small heater coil: when the lantern is powered up the lamp is unlit but the electrodes will warm up, the heater too will warm up and this will eventually cause the bimetallic strip to click open and break the bypass circuit, which will send a high voltage spike through the tube and strike it. I have a 150w SON-I /I\ lamp which has an internal ignitor and this works the exact same way. The drawback to such a system is the heater is on all the time the lamp is on, and so an extra few Watts of power get consumed.

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PostPosted: Sat Oct 18, 2014 5:07 pm 
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mazeteam wrote:
The starters will indeed be 4-pin.


These fittings do indeed look to be from around the late 50s / 60s and are very typical of the "heavy duty" designs which prevailed. A lot of the innovations at the time followed the debut of the then innovative Atlas "Popular Pack" in 1954. Aimed at the commercial market, this was hailed as the UKs first fluorescent fitting to be supplied complete with a tube. and so other manufacturers followed with their own designs.

Fittings with trough reflectors were mainly used for factory lighting. The GPO especially seemed to like them. and they can still be found in some of the less modernised exchanges.

Of course, the fluorescent lamp has been in existence since the 1930s, however whilst America had embraced this new fluorescent lighting in a very big way, promoting it in terms of both efficiency and fashion, in Britain, it was only the pressing need to increase factory production for the war effort that permitted any development here. Owing to the wartime contingencies of the time, the resultant 5' 80W tube with its standard bayonet caps was deliberately designed to use existing MB chokes, thus saving time and materials. These early fittings were quite rudimentary in the beginning, comprising a full length trough reflector with the choke and a suppressor mounted on top. The plug in starterswitch was a basic thermal type. Although the components were redesigned over the years, the basic structure was pretty much unchanged into the 1950s. When the BC tube was no longer produced from the late 70s, bi-pin to BC adaptors allowed the fitting of the new bi-pin type.

This "Mazdalux" example is in my collection and looks to be from the late 40s. Sadly, it is missing its gear shroud.
A selection of starter switches of the 1950s are also included.  A catalogue picture of the Atlas Popular Pack which challenged existing ideas of fluorescent lighting in the late 1950s is shown first.


Attachments:
File comment: This is what started it all. the first fluorescent fitting sold with a lamp. A great boon for electricians, the fitting was simplicity itself to install. A few still survive in forgotten corners.
Pop2.JPG
Pop2.JPG [ 2.21 MiB | Viewed 13994 times ]
File comment: This is an original Mazdalux fitting, probably from the late 40s. There would originally have been a steel cover to enclose the gear.
Mazdalux1.JPG
Mazdalux1.JPG [ 2.1 MiB | Viewed 13994 times ]
File comment: The existence of the MB lamp choke instigated the development of the 5' 80W tube. A simple thermal starter was used and was simply plugged in. A notch on the starter base ensured correct connection. This choke looks to be slightly later than the wartime versions.
Mazdalux3.JPG
Mazdalux3.JPG [ 2.23 MiB | Viewed 13994 times ]
File comment: A close up of the choke , starter and suppressor.
Mazdalux4.JPG
Mazdalux4.JPG [ 2.22 MiB | Viewed 13994 times ]
File comment: A close up of the bayonet capped fluorescent tube.
Mazdalux6.JPG
Mazdalux6.JPG [ 2.14 MiB | Viewed 13994 times ]
File comment: A selection of starterswitches from the 1950s. The "push in" thermal type is what was supplied with the Mazdalux fitting above. Simpler fittings of the period used the "glow" type with its SBC cap. The canister starter switch actually dates from 1980 and is a "glow" type. Although still made with 4 pins, the thermal method was obsolete by then and 2 redundant (heater) pins were simply linked out inside the cannister.
Starter4.JPG
Starter4.JPG [ 2.23 MiB | Viewed 13994 times ]

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Last edited by GreatNorburyStDepot on Sun Oct 19, 2014 10:06 pm, edited 2 times in total.
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PostPosted: Sun Oct 19, 2014 12:41 pm 
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Many thanks for your photos and explaining where the "Popular Pack" concept came from.

The starter information is of interest as well, I knew of the 4 pin type and its predecessor that was in the lampholder (via Claire) but not the very early types.

I have a couple of vintage fittings - again via Claire, her collection of vintage fluorescent lights is more extensive!


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PostPosted: Sun Oct 19, 2014 4:58 pm 
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Many thanks for your comments. I have always liked the early fluorescent fittings, as back in the 1970s and 80s there was a good mixture still to be found in local shops and offices. My local high school which mostly dated from the 50s had the original Pop Packs until 1985. Since then I have managed to acquire some quite nice examples including a 4' and 5' "seagull" fitting one of which is in my kitchen, a 5' 80W AEI "Monolux" which looks similar to the Pop pack and also a 2' 20W fitting by Ekco, which is still in its box!


Attachments:
ekco3.JPG
ekco3.JPG [ 2.2 MiB | Viewed 13962 times ]
ekco4.JPG
ekco4.JPG [ 2.14 MiB | Viewed 13962 times ]

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PostPosted: Sun Oct 19, 2014 10:02 pm 
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mad-al wrote:
you can't get BC tubes anymore!


The standard Bi-pin fluorescent tube had been the staple design in the US since the 1940s. By the 1970s, the British bayonet capped variety was still in production as it had been since the war, however it was soon to be declared obsolete. Since the 1950s, the BC range had expanded to include 8' 125W tubes (I think there was also a 4' 40W). The cessation of BC tube production however raised a problem. At the time, there were still lots of old fittings which needed these tubes, especially in schools, offices and factories and the replacement bi-pin type was not interchangeable.

The simple solution (not that you'll need telling) was the Bi-pin to BC adaptor, comprising a recessed bi-pin lampholder within a brass BC lamp cap. Thorn were obviously keen to exploit this market with their GB1515 (two required per fitting). They were easy to use as each adaptor was simply inserted onto the pins of the new type tube. The tube was then snapped into the two customary terry clips on the fitting. The BC end of the adaptors were then plugged into the existing lampholder and therefore allowed the new bi-pin lamps to be used. Using the adaptors stopped a lot of elderly fittings going to the scrap heap.

Early 5' bi-pin tubes were labelled as 80W as before, however as chokes became more compact and more efficient, future production tubes were subsequently labelled as 65(80W), then 65/80W. They could therefore be used on both new and old gear. This remained unchanged until quite recently when some brands of 5' T12 tubes were labelled simply as 65W, in recognition that the old postwar equipment was no longer considered to be part of the modern lighting scene.


Attachments:
File comment: The Thorn GB1515 bi-pin to BC adaptor showing the "tube" end.
adap2.JPG
adap2.JPG [ 2.22 MiB | Viewed 13950 times ]
File comment: A section of my 1982 Thorn price list showing the obsolete BC lamp and instruction to use a 65/80w tube and two GB1515 adaptors.
tube4.JPG
tube4.JPG [ 144.14 KiB | Viewed 13950 times ]
File comment: A close up of my "Seagull" fitting with a Bi-pin Crompton 65(80W) warm white tube. BC adaptors were used until recently, as the fitting has since been rewired and now utilises a 58W HF ballast.
tube3.JPG
tube3.JPG [ 2.02 MiB | Viewed 13950 times ]

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PostPosted: Thu Oct 30, 2014 11:41 pm 
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Further to the topic of BC capped fluorescent tubes and their contribution to the British war effort, here are a few pictures of an early choke design as fitted to the original 1940s fluorescent fittings. Notice how the 80w rating has been printed on the iron yoke, along with the voltage tapping information on the insulation board.

I am unable to confirm the manufacturer but would suspect GEC, however you may know different. It is interesting to compare it with the later version employed in my Mazdalux trough fitting. The design is an "open" transformer type and would have been enclosed in a steel box mounted on top of the fitting.

This is an interesting relic which gives no indication of how conventional fluorescent gear design would change in later years.


Attachments:
choke1.JPG
choke1.JPG [ 2.22 MiB | Viewed 13886 times ]
choke2.JPG
choke2.JPG [ 2.19 MiB | Viewed 13886 times ]
choke3.JPG
choke3.JPG [ 2.21 MiB | Viewed 13886 times ]

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