Thorn Beta 5

This lantern was given to me personally by some extremely kind and friendly workers of Tarmac's Street lighting division on Saturday 7th September 2002 who were painting columns and checking fuses on my estate when I spent over two hours talking to them, and generally hindering their progress...I spotted the Beta 5 in the back of the workers' bucket van, under some piping, and cheekily asked for it - I think they were quite happy to oblige as it was in the way in the van. Once the lantern had been salvaged from in amongst the piping, I was told that it had been removed from a street with (sleeved) concrete columns that were being replaced with steel columns - I believe that my Philips 'Iridium' SGS 253 was fitted to one of the new columns.

The men returned the following week, (Sat 14th Sept 2002) to replace a twisted metal column (a video of this work exists here), and they asked if I'd managed to get the Beta 5 going - I certainly had - it was my first gear-in-head lantern, as well as my first lantern with a photocell, and so I wasted no time in getting it going! After this, I spent another two hours or so helping/hindering them with their work; the best part being when I held the bracket from the old column before it was fastened to the new one. It is not easy holding a video camera, bracket and lantern at the same time however!

Until LED replacements occurred, Thorn Beta 5s were used extensively in Derbyshire - they were (probably) the most common side road lantern that you would see in the County.

This lantern uses a deep bowl, whereas the majority of the modern Beta 5s in Derbyshire used a shallow bowl. With this newer version of the Beta 5, either bowl type is an option; however, older versions are unable to accommodate the shallow bowl, owing to the lampholder being set at a lower position within the lantern.

A Hy-lite HL4N photocell is employed in the lantern's centrally-positioned NEMA socket. This dates from July 1996, making it older than the lantern itself. It may have been the cell fitted to the previous lantern on the column, and swapped over when replacement occurred, or fitted as a replacement if the original cell became defective.

Removing the cell reveals the top part of the Cableform NEMA socket, which dates to November 1999.

The deep bowl features refractors beneath the lamp; these are not present on the shallow bowl.

With the bowl removed, the 35 Watt SOX-PSG lamp is seen clearly. As acquired, a standard Philips SOX Plus lamp was fitted.

The identification label covers the hole in the reflector / gear tray that is cut out to support the capacitor.

With the removal of a single bolt, the gear tray hinges downwards, allowing access to the wiring, along with the gear components themselves. The upside-down label positioned on the inside of the canopy requests that installers pass the supply cable through the central hole of the gasket / grommet that is (supposed) to exist within the bracket spigot, as a way of improving the seal against water and dust ingress. The NEMA socket is seen to be bypassed, owing to the photocell not needing to operate the lantern, with it being in a Collection setting.

The Thorn G53332.4 ballast is mounted at the top of the gear tray, with the GC2435/S 6 F capacitor (white cylinder) and ignitor (silver cylinder) positioned below. The capacitor carries the manufacturing date code '100', meaning that it was made in the very first week of the year 2000.

Peering down the bracket spigot reveals that the aforementioned seal is not present anyway - I suspect that it was probably removed and discarded during the lantern's installation out on the street, as the seal's presence makes passing the supply cable through a little more tricky.

The prismatic refractors on the bowl are formed in order that the light is mainly cast downwards, as you might expect.


The lantern was mounted to an AC Ford AC872 wall bracket on Monday, 15th August 2005. This view shows the short-reaching lampholder bracket, which enables the shallow bowl to be fitted.

Lantern warm-up 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 Percentage Difference
244.5 0.51 60 125 49.8 0.47 58.61 23.61 67%
 

Thorn Beta 5s in the Collection

1970

1982

1983

1989

1998

2000

2001

2004

2006

2008

Thorn Alpha 1 | Philips SGS 204


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