Coughtrie PW.15

New and unused, this bulkhead was purchased for use as an actual outdoor light (how novel). Although the PW has been in production for many years (with the overall design barely altering from the original), this particular example is modern, but still manages to retain a feel of yesteryear.

This example features a textured black paint finish to its aluminium canopy and wall bracket (which we shall see shortly) and an opalescent polycarbonate bowl. Notice that the bowl is a flush fit to the canopy; earlier versions featured a support ring to which the bowl fitted. The lampholder is pre-wired, for convenience.

As with many Coughtrie products, the company's name and city of the product's manufacture (Glasgow) are cast into the top side of the canopy. From this angle, the fitting somewhat resembles a Thorn Beta 4 lantern. Although this fitting is threaded for a 20 mm diameter conduit, there appears to be an adaptor within the canopy's neck that converts a ¾" BSP thread to the narrower 20 mm thread.

Many Coughtrie products with refractor bowls see the refractors arranged in a series of concentric circles emanating from the centre, and vertical parallel refractors on the sides. This bulkhead is no exception to this rule.

Three equally-spaced screws secure the bowl to the canopy. The screws are captive to the bowl, ensuring that they are not accidentally lost when they are not engaged with the threaded fixing holes around the circumference of the canopy. The fixing holes have each been treated to a coating of grease, in order to assist the removal of the fixing screws. A shallow channel also cut into the circumference is fitted with a rubber gasket strip, in order to offer the innards of the bulkhead a degree of ingress protection.

The porcelain bayonet lampholder is mounted centrally. Here, the part code 'C451' can be seen cast into the underside of the canopy. Although the lampholder was pre-wired, the earth stud (visible to the right of the lampholder) did not carry a conductor wire. This being because the metallic structure of the fitting would act as a rudimentary earth path.

A simple curved length of conduit serves as the PW's top-entry bracket. Both ends of this tube carry a 20 mm diameter thread, which has also been greased in readiness for assembly. The wall-end of the bracket is intended to terminate in the 'C 417' fixing plate, which is conveniently the same size as a BESA conduit box. A couple of M4 screws allow this plate to be attached to just such a box.

The PW, bracket and fixing plate were then loosely screwed together as a way of seeing how the completed assembly would look...much as I thought it would, really! Notice that an earth wire has now been connected, in addition to the existing live and neutral wires.

The bulkhead was installed on Saturday, 24th January 2015 - as I say, the fact that the wall plate fitted exactly to a BESA conduit box was rather convenient! With the bulkhead installed, all that was needed now was for a vintage 150 Watt tungsten lamp to be fitted in the lampholder, and work would be complete...

...however, what was actually fitted was something rather different to this! This Philips 3.5 W LED candle lamp is perhaps not the most obvious choice of lamp to use; the reason behind its being chosen is because it has a lumen output that is equivalent to a 25 W tungsten lamp. Anything brighter would really be too powerful for the narrow passageway that was required to be lit.

As can be seen, the little lamp provided ample light for which to see by.

The mock-tungsten filament refractor within the lamp cast an interesting beam pattern onto the inside of the bowl.

Thorn Precinct | Coughtrie SW.10