GEC ZD10807

Lantern acquired in June 2008.

Thanks to Jon Southern for sending this lantern to me. This was one of several ZD10807s that were installed on the Westminster Bridge on Whitby Road in Ellesmere Port, Cheshire - not the Westminster Bridge in London! The lanterns were replaced with modern D.W. Windsor post-top lanterns, using the same columns. There are no known examples of the ZD10807 in Derbyshire; its ornate nature rendering it unsuitable for everyday street lighting.

The ZD10807 is an early example of a 'heritage' lantern - GEC was rather forward-thinking in predicting that there would be a market for lanterns that were made to look older than they really were. A similar design, the Z8455, was designed for running two or four 40 W fluorescent lamps. The main bodywork of the lantern is meant to be gold-painted aluminium, although, at some point, this appears to have been painted black instead. Corrosion has set in to parts of the metalwork, meaning that a full restoration will be required to get the lantern looking new again.


As with many ornate hexagonal post tops, the glazing panels are fixed to the lantern frame; however, one panel is able to hinge open to allow access to the lamp. The polycarbonate sheeting used for the glazing panels has a slightly 'figured' appearance to one side, though curiously, the longer panels have this facing inwards, whilst the smaller underside panels have the decoration facing outwards. All of the panels have discoloured over time; they would have been colourless originally. A small thumbscrew holds the hinged access panel in place under normal circumstances. Unfortunately, the upper of the two hinges has snapped, and because it was welded to the lantern frame, replacing it is made more complicated. The 35 W lamp looks lost in such a tall lantern (the lantern is not, however, as tall as the Phosco P109) - a 55 W lamp would easily be accommodated. Indeed, GEC literature states that either wattage could be used in the lantern, along with 250 W MBF or SON lamps.


This close-up of the upper part of the lantern clearly shows the over-lamp reflector. The rusted bolt above the glazing panel on the left is fastened to an internal bracket, which holds that particular panel in place. Each of the other panels are fixed in the same way, although at three points around the lantern, there are additional bolts - these support the reflector. I have yet to see how much effort will be required to remove these!


The six smaller glazing panels are simply attached to the lantern frame with adhesive material.


The conical canopy section still retains much of its black paint.


The gear is concealed beneath the canopy. In order to get to it, the finial and gasket are removed, and then the canopy simply lifts away. The lantern is fitted with the same type of ballast as seen in the older Z9532 and Z9539 in the collection - the original label has long since disappeared. The capacitor (possibly) dates from 1975, although corrosion on the casing means that the date stamp is difficult to read. This would be concurrent with the approximate age of the lantern, however.


Disassembly of the lantern commenced on Friday, 27th July 2018. Such was the severity of the corrosion that virtually every single nut and bolt was damaged beyond repair - most sheared as I tried to undo them, whilst others had to be cut apart with a hacksaw. Even with these removed, the glazing panels still had to be prised out, owing to the adhesion material holding them in place.


Notice the corrosion build-up on the parts of the lantern frame where the bolts passed through.


The damaged hinge was removed and its remains filed down in preparation for a replacement.


In typical GEC fashion, two of the three 316″ grub screws were removed without too much effort, but the third was considerably more stubborn and would require drilling out, the hole re-tapping and a new grub screw inserting.


The nut and bolt securing the porcelain connector block also put up some resilience, but did release after being heated with a blowtorch. This caused the porcelain to break, although it was already damaged upon acquisition, and wasn't to be re-used anyway. The earth screw was also in no hurry to go anywhere, and this too remained jammed.


The lantern returned from having its door hinges replaced in early October 2018. With thanks to TAS Engineering of Burton-Upon-Trent for carrying out this work.


Once the frame is repainted, the new hinges will blend into the frame with ease.


Proof that the door opens smoothly now!


Meanwhile, the polycarbonate glazing panels were given a much-needed wash, in order to remove approximately 33 years of road-produced dirt from them. The panels employed in the upper section of the lantern are seen below, following their cleaning.


The lantern frame, canopy and internal reflector were sent to Nuns Street Plating, of Derby City Centre, for stripping down and repainting. The external metalwork was repainted bronze, whilst the reflector was repainted gloss white.


This shade of bronze complements the 1970s' design of the lantern.


The bare lantern frame, still awaiting the fitting of the components.


On Friday, 23rd November, the frame was attached to a post-top stand using new grub screws, and the lower glazing panels were reinstated, with hot-melt glue securing them into position.


For ease, new wiring was introduced, and the lamp support re-fitted, prior to the replacement of the upper glazing panels (except for the door panel).


Whilst the door panel is secured by four tabs that push into place and hold the panel rigid, the 'fixed' panels are held in place with angled aluminium strips. The worst of the corrosion to these was removed using an abrasive soap pad. A strange quirk with the lantern, as acquired, was that the frosted effect of the glazing panels faced outwards in the lower section, and inwards in the upper section. All of the panels were turned for the frosting to face outwards as part of the restoration.


With the upper panels installed (complete with new foam gasket strips at the top of each), the next task was to re-fit the lampholder and control gear to the reflector. Unfortunately, the slotted heads of the terminal screws on the existing ballast were too worn to allow them to be moved, and my spare ballast of the same type was discovered to have an earth fault. Thus, a modern electronic 35 W SOX ballast was drafted in as a last-minute substitute, and fitted perfectly in the available space on the reflector.


With the lamp, canopy and finial back in place, the door was closed, and the lantern was all set to run again.


The lantern offered a very attractive lit appearance, with the diffused SOX lamp looking particularly suited to its surroundings.


Lamp warm-up video:

Testing the lantern with my energy monitoring device revealed the following results. As can be seen, the ballast must be under-running the lamp slightly (not that this is noticeable), given that the total power consumption is less than the stated lamp wattage.

Test Voltage (V) Current being drawn at full power (A) Measured wattage (W) Apparent Power (VA) Frequency (Hz) Power Factor True Power (W) Difference (W) Percentage Difference
240.7 0.12 28 29 49.8 0.98 28.31 -6.69 -19%

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