Benjamin Duoflux

Floodlight acquired in November 2019.

Until discharge and halogen floodlighting became commonplace in the 1980s, this distinctive type of floodlight was the go-to solution for providing night-time area illumination; even today, a number of examples can be seen throughout the country, with some continuing to soldier on in the era of LED floodlighting, although many examples have become abandoned and disused with the passage of time. Although not unique to Benjamin's product range, their versions seem to be the most common, with examples produced by contemporary companies being mistaken as Benjamin products on occasion. All are known, colloquially, as "Shovel" floodlights, owing to the shape of their reflector system. Along with collectors, in more recent years, these fittings have attracted the attention of designers trying to create an 'industrial' retro appearance to homes and businesses. This example is believed to have been used in south London, but being an eBay win, little else is known of its history.

This particular example is intended for mounting post-top to a suitable spigot, although side-entry brackets and wall mounting options were available too.


The Benjamin logo and 'Made in England' are cast into the aluminium body of the lantern.


The floodlight's tilt angle can be adjusted by loosening this nut and bolt, moving the fitting up or down, and then re-tightening the fixings. Notice that these are stainless steel, and thus, are likely to have been fitted by a previous owner as part of a basic restoration at some point.


The main body of the floodlight comprises an enamelled steel reflector, with the lamp situated at the back. Along with providing a degree of directional lighting, this also offers the lamp protection against rainwater. No form of cover or bowl over this area exists - the floodlight was intended to be run with the lamp exposed. Unfortunately, this has caused corrosion to form around the rim of the enamel, along with the aluminium plate that the reflector retaining bolts fasten onto. An asbestos gasket spaces the plate from the reflector. Sadly, the 500 Watt GLS lamp that was included with the lamp has a broken filament. Any manufacturer's franking on the lamp is long gone, destroying any chance of being able to decipher a production date code, and thus, allow an approximate guess as to when the floodlight was last lit, to be made. As an alternative to the use of GLS lamps, high-wattage mercury vapour (originally, MA/V; more recently, MBF) lamps could be fitted, thanks to the floodlight incorporating a GES (Goliath Edison Screw) lampholder.


Two square bolts would secure the floodlight to its post when in use.


The wiring passes through the aluminium top section of the fitting, and should be able to be guided through the section by removing a series of fixing screws; however, all were jammed upon acquisition, and so viewing the internal layout is not possible at present. When new, the Benjamin logo would have been present on the top section of the reflector.


Thanks to the efforts of TAS Engineering of Burton Upon Trent, the jammed components were separated - the picture below was taken in January 2021, just before the floodlight underwent full blasting and repainting.

The lampholder was unusual in that most conductive parts were exposed, rather than being shrouded within the porcelain cylinder, as with other lampholders.

The two brass screws on the top section each attach to a small fin that clamps the lampholder to one of several focal positions that are cast into the inside of the neck section situated above the reflector.

Following disassembly, the central porcelain section appeared to be happy at the prospect of receiving an imminent cleaning!

The other side of the porcelain also carries Benjamin branding, along with the stamped number '2988'.

TAS also fabricated a replacement shim in aluminium sheet. Using the new shim as a template, I cut a piece of neoprene rubber to the same size, to serve as a replacement for the original asbestos gasket.

The rest of the components were bead blasted and (re)painted by a local refurbishment company. The aluminium parts were painted hammered grey.

The outer side of the reflector was repainted into the same light grey that it had been painted originally.

The inside was repainted gloss white, as would be expected.

Using new stainless steel bolts and dome head nuts, the floodlight was then reassembled. The original square-headed securing bolts, and hinge pivot nut and bolt assembly, were re-used.

Side view.

As this underside view shows, the lampholder and wiring had not been reinstalled at this point.

The corroded copper and brass lampholder components were dipped in vinegar overnight, whilst the Bakelite insulator and ceramic base were cleaned in a solution that was rich in washing powder. Once dried, the jigsaw puzzle of reassembling the lampholder commenced.

Several small studs in the threaded part of the lampholder allow a ring of insulating material to clip into place. I can't work out the purpose of this ring, but included it for completeness nonetheless.

Re-fitting the lampholder into the floodlight was a rather fiddly task, and took several attempts before the fins engaged correctly - the problem is that if they are too far down the bolt, they spin constantly, as there is nothing to prevent this at that distance, but too far up, and they miss the part that they are supposed to clamp against, and there is no way of seeing the bolts (or fins) when the lampholder is in place. I elected to use the middle focal position.

TAS produced a wall bracket with an upward-pointing curved section, especially for accommodating the Duoflux.

The floodlight was wired up before being slid into place on the wall bracket.

There aren't many LED lamps that have a GES lamp cap; however, the Bailey SpiraLED decorative LED filament lamp is one that does, and is a very close match size-wise to the old tungsten lamp, and so was duly installed in the fitting. This did make the Duoflux more suitable for a trendy Soho wine bar than a suburban Derbyshire living room, however!

The lamp produced a warm white glow when switched on.

The floodlight's shovel-shaped reflector ensured that the majority of the output was concentrated forwards.

With the camera's flash activated, the warmness of the light becomes more apparent.

The long LED strand produced an interesting reflection on the inside of the floodlight.

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
244.9 0.07 14 17 49.9 0.82 14.06 -0.94 -6.28%

Operation video (this features a Calex Giant XXL lamp, rather than the SpiraLED type seen above):

Thorn 'SONPak 7' OT 70.4 (1993) |




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