Thorn Beta Six / AEI Saxby

Lantern(s) acquired in April 2021.

These two lanterns were installed alongside the Leander Architecture building on Hallsteads Close, Dove Holes, Buxton, and were photographed previously as a Survivor from the Past article. The condition of their columns was becoming increasingly poor, especially after one was struck by a vehicle in 2020, and so, the building's landlord decided to remove them; this taking place on Saturday, 10th April 2021. Thanks to a previous request that I made for these, the lanterns (and their brackets) were saved for me, and I picked them up a few days later - thank you to Leander for agreeing to my request, and for holding onto them until I could pick them up! No other known examples of Beta 6 lanterns exist in Derbyshire - their twin 40 Watt 2 ft (600 mm) fluorescent lamp requirement never being a popular choice for street lighting in the area. Rather appropriately, the Bedfordshire village of Great Barford (no relation!) retained several Beta 6 examples until the mid-2000s. A short road off Jordangate, in Macclesfield, Cheshire, is also home to three of these lanterns, along with a Phosware P141.

The first column, pictured in 2017, looking rather the worst for wear.

Even from the ground, the absence of lamps in this lantern was obvious.

The second column was in equally bad condition at the time.

The innards of this lantern appeared more intact, however.

The two lanterns, in as-received condition. The lantern without lamps turned out to be an empty shell, with the gear tray missing completely. This is the worse of the two lanterns - its acrylic bowl features a number of cracks. The aluminium brackets are, as would be expected, still in very good condition, and should clean up quite nicely. The lantern that retains its innards sees both lamps stacked vertically, with moulded prismatic refractor prisms on the sides of the bowl providing limited optical control.

The bowl design features no refractors beneath the lamps, although some faint patches of dirt and greenery exist in both of these examples.

Holes have been drilled at the backs of both bowls, in order to reduce the amount of water that is retained within the fittings.

As the old columns were cut, this view allows their hexagonal construction to be appreciated, along with the method employed to clamp the brackets to them.

The aluminium canopies of both lanterns are also clean and free of corrosion. Neither is drilled for photocell control, suggesting that the lights may have been switched remotely.

The front and rear ends of the lantern resemble those of the contemporary Beta 5.

With the two toggles released, the bowl hinges open and detaches easily. A self-adhesive sealing gasket is installed around the edge of the bowl, in an attempt to improve the sealing - this may be another modification made in service to try to reduce water ingress. Judging by the state of the gear tray / reflector, these efforts appear to have been rather fruitless.

Barely legible towards the back of the gear tray is the lantern's (very brittle) identity label, with both 'Beta Six' and 'Saxby' names included, though it is definitely a Thorn product, rather than AEI, as the Thorn logo is present on the left-hand side of the label (trust me; it is!). As well as the twin 40 Watt lamp type, there is also the inclusion that the lantern is made to B.S. 1788:1964 (Street Lighting Lanterns for use with Electric Lamps) - this being an amendment to the original BS 1788: 1951 (Street Lighting Lanterns - Electricity and Gas), but was, itself, superseded by BS 4533-103.1 (1981) (Luminaires - Performance Requirements - Specification for Light Distribution from Road-Lighting Lanterns).

Some of the phosphor coating has 'blown' off the lower lamp, although it may still work. Both lamps are made by Philips, and carry the date code '2A', which (for reasons that will become clear in a moment) represents January 1972.

The four lampholders are connected to flying leads, rather than two being fixed, as with the GEC Z8260; however, four fixed 'Terry' clips are installed instead, ensuring that the lamps are secure when in use. These have become rather stiff over time, and I had to be careful not to break the lamps when releasing them from the clips. The gear tray is held in place with two screws that keyhole into position. Of course, while the front screw turned with ease, the rear screw wasn't quite as accommodating, and I had to hammer the gear tray forward, in order to be able to remove it. As it is only a length of sheet steel with the edges bent over, a replacement could be fabricated, if necessary.

The lampholders carry British Lighting Industries (Thorn) branding, and naturally, proclaim that they are "made in Gt. Britain". Notice that both lampholders have earth wires attached, with these connected to a brass component that makes contact with the metallic end caps of the lamps. This assists with lamp starting in colder temperatures; indeed, both lamps appear to be of the MCF/A type, which features a thin strip of conductive material being applied along the length of the tube. For the most part, this coating has worn away, owing to the age of the lamps.

The gear comprises an AME 69082.4 Quickstart ballast (for running both lamps) and BICC Power Factor capacitor. As can be seen, the paint is flaking badly on this side of the gear tray, as well as on the ballast itself. I will attempt to see whether it works, however.

The ballast also carried British Lighting Industries branding.

The capacitor is dated to February 1972, meaning that the lamps fitted now are highly likely to be the very same lamps that were fitted almost fifty years previously!

The lantern was sent to TAS Engineering of Burton-upon-Trent, for some much-needed remedial work. Owing to the concern that the casting would be damaged while trying to remove the trapped bracket (or the bracket itself would be), the decision was taken for it to be left in place. Following their work, the parts were taken to R.L. Dumelow & Son, also of Burton, for bead blasting and repainting. The canopy was painted chrome aluminium at this time, while the gear tray / reflector was painted gloss white, after having been knocked back into shape from when it was hammered loose, owing to the jammed retaining screw. The bracket itself was left unpainted, but received a cleaning and sanding.

The rusty gear tray cleaned up very well, despite being in such a state as received.

TAS was able to remove the section of the old column that remained within the bracket's spigot cap.

The next task was to check to see whether the lamps (and gear) would work...amazingly, they all did (although, at first, only the lamp electrodes glowed, but I think that this was due to a poor earth connection initially, as the lamps sprang to life with slight coaxing). Thus, the lantern was ready to be reassembled. The bowl was cleaned and reinstated.

At this time, the bracket supporting the front two 'Terry' clips that held the lamps steady was yet to be fitted.

A new self-adhesive gasket strip was applied around the dedicated channel around the edge of the canopy. I had removed the additional gasket strips that had been applied to the bowl, although, I could see why these had been added, as the bowl is not a tight fit against the canopy; indeed, the holes for one of the securing clips appeared to have been drilled incorrectly during manufacture, causing the clip to lean at a slight angle.

As the existing manufacturer's sticker was so badly faded and crumbling, a replacement was produced to the same style as the original, and placed in exactly the same position on the gear tray. A ZIP file containing the Microsoft Publisher PUB file and PDF copy of the label design can be downloaded by clicking here, should anyone wish to use the template for producing their own replacement labels for AEI and Thorn lanterns of this era.

Replacement slotted screws measuring 3/8" in length and having 8-32 UNC threads were sourced, in order for the front support bracket to be re-installed.

Keeping with the imperial theme, new 1/2" long, 3/8"-16 UNC grub screws were installed in the bracket's spigot cap, and the whole assembly was attached to a post-top stand, also fabricated by TAS and painted by Dumelows (in hammered grey this time), on Friday, 7th January 2022.

Lengths of earth wire were wrapped around each lamp, and the ends fitted with spade crimp terminals, which were then sandwiched between the metal ends of the lamps, and the lampholders, in order to replicate the conductive earth effect of the long-gone strips applied to the lamps during manufacture.

A similar view to that seen above, except that this time, there is the proof that items made fifty years ago were built to last, as the 1972 lamps and gear flickered into life.

The refractor prisms attached to the long sides of the bowl performed amicably at diffusing the majority of the luminous flux produced by the two lamps.

Lantern operation video:

Testing with my energy monitoring device revealed the following results:

Test Voltage (V) Current being drawn at full power (A) Measured wattage (W) Apparent Power (VA) Frequency (Hz) Power Factor True Power (W) Difference to rated wattage (2 40 Watt) Percentage Difference
239.6 0.6 93 144 49.9 0.63 90.57 10.57 13.21%

Thorn Gamma 3 | ELECO HW-852




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