4AB. Duke Street, Derby City Centre Located at the junction of Mansfield Road is a 35 ft (10 m) tubular steel column that supports a Thorn Alpha 4 lantern running a 135 Watt SOX lamp. The Alpha 4 has the accolade of (probably) being Derby's last-remaining working 135 Watt SOX lantern by September 2022, which is notable in itself, but of further merit is the fact that the column is also the last of its type in the City, and would have supported a twin-lamp Atlas Alpha 8 lantern originally. The installation may have avoided renewal as part of Derby's Street Lighting PFI mass-replacement programme, owing to the following couple of columns on Duke Street (at the point where it crosses the River Derwent on Saint Mary's Bridge) being considered new enough not to require replacing.
The column is of a design where the diameter reduces at regular intervals, until it becomes narrow enough to accommodate a lantern on the end of the bracket.
An additional reducer was installed after the Alpha 8 was removed; these lanterns require a 11/2" BSP (48 mm) diameter bracket, whereas most main road lanterns can accommodate spigots with a maximum 11/4" BSP (42 mm) diameter.
The Alpha 4's front clip is broken, requiring the application of a length of insulation tape to keep the bowl steady. A section of the internal gasket is also hanging out of the lantern. A Royce Thompson SC1000/SAV 35 Lux photocell switches the lantern on at dusk and off at dawn.
The column was photographed just after 7AM in early September 2022; hence. the rather atmospheric sunrise seen behind it.
Unusually, the column also supports an illuminated Give Way sign, with a twin eight Watt fluorescent Forest City Exlite signlight providing the dedicated brightness to the sign plate during the hours of darkness. The column is numbered 35224, while the sign is 102109; both of these are their original Derby City pre-PFI numbers, and appear in the pre-1997 inventory records for the Authority:
|Seq. No.||Lamp Number||Location||Lamp Type||Watt||Isolation Point|
|1||35224||CNR MANSFIELD ROAD||SXPL2||135||Y|
|2||35225||ON LHS OF RIVER BRIDGE||SONE||70|
|3||35226||ON RHS OF RIVER BRIDGE||SONE||70|
|4||35227||OS ST MARY'S CHAPEL||SONE||150|
|5||102107||JUNC MANSFIELD RD||FL||11|
|6||102108||JUNC MANSFIELD RD||FL||11|
Originally, there were two inspection doors to this column (a necessity, owing to the dual control gear sets that the base would have accommodated when the Alpha 8 was fitted); a third, newer, door has been added to cover a corrosion hole in one of the two older doors. The signlight is operating in daylight - another nod to the pre-PFI era, when signlights in Derby were, generally, lit constantly.
The installation is pictured again at dawn, with its 135 Watt SOX lamp glowing radiantly.
The bowl might be taped in place, and part of the sealing gasket has detached, but the Alpha 4 soldiers on regardless.
From this angle, numerous light sources are visible. Along with the SOX, there is the fluorescent lighting of the signlight, the SON floodlighting of Derby Cathedral in the background, the CDO-TT lighting of the Philips 'Iridium' SGS 254 in the foreground, and finally, the LED technology of the OrangeTEK TerraLEDs on St Alkmund's Way.
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