Atlas Gamma Two

Lanterns acquired in March 2025.

This Gamma 2, along with the remains of another, were removed (with permission) from within the compound of the Acuren / Applied Inspection building on Mosley Street, Burton-upon-Trent, Staffordshire, on the 25th March 2025, along with the life-expired tubular steel columns that supported them (although I didn't request that these be saved for me). While these particular examples can no longer be seen in Burton, another Gamma 2 can still be found elsewhere in the town, although it has not worked for many years. The Gamma 2 was launched in 1956 (along with many other new lanterns by Atlas Lighting), and remained in production until 1972, with sister lanterns the Alpha 2, Alpha 10, Beta 9, Gamma 1 and Gamma 9 also being discontinued permanently after this year - presumably, these were the worst-selling products by then, and Thorn took the opportunity to reduce their lantern portfolio to the more popular products. Another factor will have been the relatively high power consumption of fluorescent lanterns compared to the amount of illumination offered, with only the Beta 6 remaining in production until 1981 - the 1970s being rather infamous for energy crises that put paid to these lanterns being specified.

With tremendous thanks to Pat and Joe at Acuren for their assistance in allowing me to secure these lanterns, and to Balfour Beatty Power Networks for carrying out the column removal work, and ensuring that the lanterns were undamaged during removal.

The Gamma 2 stands at 32 inches (812·8 mm) tall, with its widest point measuring 11 inches (279·4 mm) in diameter. The lack of any lamp control gear within the lantern itself keeps the weight down to a comfortable 13 lb (5·84 kg).

A wide thumbscrew on top of the lantern holds it together in normal operation. The thumbscrew is slightly off-centred in this view as the weight of the internal spine causes the thumbscrew to lean when the lantern is on its side. Originally, the top section would have been coloured light blue - while this is still obvious, the original colour has faded over time.

The aluminium base casting would have been finished in grey originally. Three grub screws requiring a ³/₁₆" Allen key are positioned at 120 degree intervals. While these are seized, one must have moved sufficiently during removal to allow the lantern to be separated from the column.

The thumbscrew itself also proved problematic to remove - the combination of a pair of grips, copious amounts of spray-on lubricating grease, my Grandfather's old Black & Decker Workmate, and a sprinkling of certain choice words all played a part in freeing it after considerable effort!

The bowl and top section are moulded in acrylic, and are permanently bonded together. The bowl is formed of two pieces that are also bonded - one of these seams is beginning to split, which will require the application of adhesive to re-secure the two parts.

Lifting the casing clear reveals four 40 Watt fluorescent lamps positioned around a steel spine. The lamps all exhibit the characteristic blackening at each end that indicates that they have reached end-of-life (some more than others).

A disc is welded at both ends of the spine to support the bi-pin lampholders. The top disc also supports the two starter switches and their holders, as well as the thread that the thumbscrew fastens into.

A four-way connector block is provided at the other end of the spine. This allows both lamp circuits to be connected (two lamps per circuit), with the neutrals for both circuits sharing a common return wire. A separate solid green conductor provides an earth connection - it wouldn't be until 1977 that the now-familiar green and yellow colouring would denote the earth. The disc at this end of the spine features a wider thread that allows it to screw into the base casting.

Back at the top disc, the starter holders are sandwiched between the two lamps that they switch.

The starters employed are two AME 32000 types. These are possibly not the original starters, given that they carry Thorn branding (rather than Atlas), and the logo design looks to be one of Thorn's later variants. Notice that the starter casings appear to have been blue originally, but this has faded to a mauve where the plastic has been exposed to sunlight, along with the UV produced by the lamps over the years.

The starters are somewhat larger than the typical fluorescent starters of later eras were. This is because they employ two individual starting circuits (hence, the "Double Glow" name seen above), owing to the series operation of the two lamps. Rather than requiring two starters per circuit, these save space in the lantern by incorporating both starting circuits into a single unit. A novel idea, though sadly, they were more expensive than standard series starters would be, and eventually, succumbed to the more standard design incorporating only a single starting glow discharge vial.

With the surrounding lamps removed, the starters are seen more clearly in their holders.

Removing the lamps was a delicate procedure, owing to the aluminium end caps having corroded and (in some cases) lost adhesion with the glass tubes.

With the lamps removed, the setup around the lower disc is seen more clearly. The lip around the top of the base casting would have supported a gasket ring originally; now, only a small portion of this survives.

Three of the lamps were Crompton-branded (but made by Philips) products, while the fourth was an OSRAM 'Liteguard'.

The franking had faded heavily on all lamps, but when held up to the light, the ghost image was revealed. The date code F4 indicates that the Crompton lamps were produced in June 1984.

The Liteguard carries the date code 'PD', which represents April 1982.

The second Gamma 2 is in poorer condition, owing to the plastic parts having gone missing many years earlier.

The lack of any outer casing has caused moisture to gather beneath the lower disc, rotting away the steel thread. This suggests that the spine was only still upright thanks to the supply cable holding it steady.

A compression gland is positioned on the column side of the casting. This would also have contributed to the thread corroding away, as its use in keeping the lantern free from insect or spider infestation by forming a tight seal around the cable has also prevented trapped water from escaping. Although three drainage holes are drilled into the casting, as can be seen above, they did not link to the raised central section.

The snapped thread is evident on the underside of the lower disc.

The exposure to the atmosphere has left the lampholders in a very poor state of repair, along with the starters and associated wiring.

No thumbscrew was present in the lantern either, leading to its thread in the top disc appearing dull and rusty.

Only three lamps remained in this fitting, with one of these appearing to have especially yellowed phosphor.

Despite this, all three lamps carried OSRAM branding, with a 'white' colour appearance, and the date code 'RK' - October 1984 - presumably, the 'Liteguard' name had been discontinued by then. The fact that the lanterns were last re-lamped in the mid-1980s is rather impressive - I wonder when they stopped working. Another point to consider is that the last time the more intact of the two lanterns would have been opened would be some point before I was even born (there isn't much that I can say that about these days)!

The original fused cut-outs and ballasts were also rescued - for convenience, the ballasts were supplied by Thorn attached to a pre-wired gear tray, which then fastened onto the column backboard. Each ballast would run two lamps. As some Gamma 2s were only wired to run two lamps anyway, there were two separate gear types available: QG2.B2240.T (two lamps) and QG2.B.4240.T (four lamps). I have produced a full wiring diagram for these gear sets and lanterns; this can be downloaded (as a PDF file) here.

The ballast markings are now very faint, but were most visible on this example. The text here states:

atlas DOUBLE FORTY

CHOKE FOR SERIES PAIR

2 FT 40 W LAMPS 50 C/S

200 - 250 V

CAT NO BL 2844.T

Although each ballast features four terminals, these work just as regular fluorescent chokes do - with a live input wire and a ballasted output wire. The choice of terminals is (presumably) to allow for occasions where the supply voltage differed from the expected (at the time) 240 Volts.

Both gear sets contained a separate BICC AME C2216 capacitor, connected across the main live and neutral supply wires. The cleaner of the two capacitors indicates that it was manufactured in September 1965, which would be accurate for the age of the lanterns. Notice that this picture is taken outdoors - the casing of this capacitor has been pierced, causing the internal oil to leak out. Owing to the capacitors being the age that they are, this oil could contain harmful Polychlorinated Biphenyls (PCBs), and so I have kept both capacitors outdoors for safety.

Back indoors, and opening the fuse carriers of the Lucy cut-outs revealed large, barrel-type five amp cartridge fuses produced by English Electric. This company would cease to exist after 1968, following a takeover by the rival General Electric Company.

Restoration work commenced only days after the complete Gamma 2 was acquired. I began by removing the lampholders, starter holders and connector block. While the screws holding the lower lampholders released easily, those on top were far more heavily corroded, and required drilling out. This resulted in two becoming damaged; however, three of the more intact lampholders were retrieved from the second lantern (one serving as a spare), to make up the full complement of eight. As the upper lampholders will carry no electricity when the lantern is restored, their internal condition does not matter - provided that the springs from the second lantern are still good (which they are), they will support the replacement lamps adequately. The wiring removed with these components is heavily faded at points where it was exposed. The insulation on these sections is also cracked and chipping.

The rear of each lampholder carries the text:

Made in Gt. Britain

by

T.E.I. LTD [Thorn Electrical Industries]

Cat No.  B1502

2·5 A. 250 V.

The connector block is a 'Grelco' product, and, unsurprisingly, was also made in England.

Four brass terminal screws are provided on the rear of the starter holders - compare this to the modern starter holders, where wires are pushed in, and are then fixed permanently.

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