Thorn Alpha 8
Lantern acquired in May 2011.
This lantern came from column 36394 on Uttoxeter Road, Mickleover; its removal brought about by a relighting scheme as part of Derby's Street Lighting PFI in April/May 2011. The electrical supply to the column was removed on Friday, 13th May 2011 (ominous!) in preparation for the column's removal from service a day later. This, and a second Alpha 8 (installed on the adjacent column 129998, where my integrally-geared Philips MA 50 came from in August 2003) were installed on or before Monday, 21st February 2005, in order to provide higher light levels on the adjacent zebra crossing; there had previously been a remotely-geared MA 50 installed on this Alpha 8's column. Coincidentally, column 36394 also had the accolade for being the last of the 'old' columns on Uttoxeter Road to both remain in lighting, and remain installed.
The inventory record for the column (as it appeared in 1997, when still fitted with the MA 50) is displayed below:
|Unique Number:||36394||Location:||O/S MIDLAND BANK|
|Postcode:||DE3 5DA||Road:||UTTOXETER RD|
|Lamp Type:||SXP3||Wattage:||135 W||Control Type:||PE2E|
|Lantern Type:||SE||Lantern Manuf:||Control Gear:|
|Height:||10 m||Support Type:||CM||CONC COL/METAL SLEEVE|
|Bracket Proj'n.:||m||Support Finish:||U||UNPAINTED SUPPORT|
|Bracket Type:||U/G or O/H:||U||UNDERGROUND|
|Board Code:||E76||Status Code:||0||USUAL / NORMAL|
|Service Owner:||A||Is this lamp/sign an Isolation Point ?:||N|
|EB Order number:|
|No-supply sheet:||0||Isol Pt||:||102272||/ Circuit:||1||/ Seq:||1|
|Location||:||O/S STEVES FISH BAR|
RELAY/DETECTOR W/S 404976 7/6/96
LAMP FITTED 07 05 1996
The first few photographs show the lantern whilst still installed.
The lanterns had not long been fitted in these first couple of photographs; taken on a wintry Wednesday, 23rd February 2005.
A few months later, in July 2005, and the snow has all gone - funny, that! Although this photograph only pictures the other Alpha 8, the shadow of the column supporting the acquired Alpha 8 can be seen on the carriageway.
Slightly more up-to-date now; these photographs show the installation in its final weeks of operation, in April 2011.
The replacement column had received a lantern by the 17th April:
This version of the Alpha 8 (featuring a GRP canopy and aluminium chassis) was introduced by Thorn in the late 1980s as a replacement for the earlier all-aluminium Alpha 8 (a design which was approaching its tenth birthday by then). The original Thorn Alpha 8 was an indirect 'replacement' (by name only) of the bulky dual-lamp Atlas Alpha 8 that was produced throughout the 1960s, but quickly fell out of favour (and production) during the more "energy-aware" 1970s. The first of the 'new' Alpha 8 lanterns appeared in about 1978, and production of the lantern (in both of its Thorn guises) continued until the mid-2000s, when the Civic replaced it.
The one-piece construction of this version's canopy does away with the distinctive rear 'shoe' of the earlier design. Having been in use for over six years, the canopy's fibres are beginning to shed.
Although the bowl is the same physical size for both versions of the Thorn Alpha 8, their means of attachment at the front vary slightly, with the result that trying to fit a newer (non-refractor) bowl to an older lantern will work, but there will be a small gap around where the clip attaches. Along with the change to a GRP canopy, this version of the Alpha 8 brought about additional alterations - the lantern could now accommodate SON lamps up to 400 W, and three optical types were offered - a shallow polycarbonate bowl (as seen here), a deeper polycarbonate bowl (used when 400 W lamps are fitted) and a flat glass cover. Curiously, Thorn literature states that if the lantern is initially supplied to work with a bowl, it cannot be converted to flat glass operation. Using an adaptor, the lantern could also be post-top mounted. The 20 mm diameter hole that is visible between the two side-entry grub screws would act as the cable entry hole if the lantern were so equipped.
The underside of the lantern's chassis has the Thorn EMI logo embossed into the casting. Even after Thorn and EMI demerged, this detail was not updated (although some examples feature a raised block in place of the EMI suffix); thus, even the final Alpha 8s produced would have carried this 1980s' company designation. The two screw ends visible at either end of the logo are for the screws that secure the ballast to the chassis.
With the bowl unfastened, the reflector panels become considerably shinier - I think the bowl may need cleaning!
Although this version of the Alpha 8 is known as the "Mk 3" by collectors, it is officially the "Mk 16"! The "05 04" code in the top-left corner of the identification label suggests that the lantern was made in May 2004.
Another change that Thorn made to this version of the Alpha 8 is that the canopy now tilts forwards in order to allow access to the gear and wiring, in a similar manner to that employed by the Philips SGS 204. This is an improvement on the 'trapdoor' mechanism employed in the earlier version, as space was always rather limited in the gear compartment. Two captive screws located in the rear of the canopy prevent it from accidentally tilting forwards during normal operation.
A retention chain ensures that the canopy cannot over-tilt when unfastened. A number of drainage holes exist in the chassis; despite this, the gear components were not too "spidery" when the lantern was removed.
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