Thorn Precinct

Thanks to John Mitchell for supplying this bulkhead. This fitting is unusual in as much as it can be either a bulkhead or road lighting lantern, depending on whether a post-top adaptor is fitted or not. This particular example does not feature the adaptor, and so is intended for direct wall mounting. Post-top examples can be seen adjacent the Central Library in Burton-upon-Trent, on 5 m Thorn aluminium columns. A somewhat rarer option was a double post-top adaptor, whereby two lanterns would be fitted almost back-to-back to each other.

The Precinct was launched in 1973, and this heritage is clearly visible in the very sharp angles and straight lines employed in the design. The polycarbonate bowl has yellowed over time - whilst some of this may be due to daylight, the mercury lamp will almost certainly have contributed to the aging of the plastic.

There are many 20 mm knockouts on the back section of the fitting in order to allow for multiple cable entries. This makes the Precinct quite a versatile design.

Whilst the top of the fitting is flat, fitting a NEMA socket would be difficult due to the internal construction of the lantern.

The white paint in the lamp area is flaking due to corrosion on the aluminium bodywork. A metal identification label is pop-riveted in place; later versions were fitted with adhesive labels.

Unusually, the majority of the fitting's body has to be removed in order to gain access to the gear and wiring. The two screws visible below the lampholder can be loosened in order to lower the front section of this part of the lantern, as seen below:

The original capacitor has been replaced with a DNA branded one at some point, although I would think that the ballast is original.

The translucence of the bowl has quite a detrimental effect on the overall light output; of course the yellowing may further reduce the output, not to mention make the bowl now resembles an oversized block of cheese!

Lamp warm-up video:




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