Wardle Avon

Lantern acquired in April 2009.

Thanks to Richard James of Harrison Lighting for this unused lantern.

The lantern is fitted with a Holophane glass bowl. The bowl support ring is held in place with a wing screw, which locates into the upper canopy. Whilst this reduces the possibility of the bowl accidentally swinging open in service, I do wonder whether this may also prevent the bowl from being opened if the screw ever seized up through corrosion - not that this particular lantern will suffer this issue. Despite being new and unused, the hammered grey paint finish applied to the canopy is flaking, revealing the aluminium beneath. This suggests that the lantern was stored in a damp environment for a time.

 

Oddly, the top-entry spigot on this lantern is to a 1′′ BSP tapping, rather than the more common ′′ BSP thread used for Group 'B' lanterns.

 

A small notch is cut in the bowl support ring in order for a moulded peg on the bowl to locate into it - this allows the bowl to be correctly positioned within the lantern for lamp focusing.

 

A reflective disc surrounds the lamp. The positions of the three screws holding the disc in place mean that it can only be installed one way around. Whilst this lantern is not fitted with an internal refractor (due to the bowl containing the refractors itself), other versions of the lantern featured a clear bowl and internal refractor - this would also need to be located correctly, in order for the lamp to focus accurately.

 
 

The lantern was fitted to a wall bracket on Friday, 6th July 2018. A 1′′ BSP right-angled bend and coupler were supplied with this particular bracket, in order to accommodate this lantern. All internal screws and fixings, including the bowl wingnut, were treated to a liberal coating of copper grease at this time.

 

A 6 W GLS-shaped LED lamp was fitted - this provides a comparable lumen output to a traditional 60 W filament lamp. At this point, I realised that I had never pictured the lantern's internal lamp focusing mechanism, and so, took the opportunity to do this. The highest focusing position is for 200 W GLS, 160 W MBFT and 125 W MBF lamps, followed by 150 W GLS (note that bayonet-capped lamps have to be situated slightly higher up than lamps equipped with Edison Screw bases would be), 80 W MB/U and MBF, and finally, 100 W GLS. Again, the position for a bayonet-capped lamp of this wattage is different to that of an Edison Screw-capped lamp. Such is the age of this lantern that the focus positions are based on older lamp sizes (the various mercury vapour options, for example, are intended for the earlier 'pear-shaped' lamps - newer elliptical lamps are too wide to fit through the narrow aperture in the reflector at the correct focus position. As it is, the modern GLS size (which was kept the same for the LED replacement lamps) is too small for even the 100 W positions - these would situate the lamp too far up into the lantern. Thus, the lampholder is secured as low as possible on the focusing mechanism, ignoring the set positions indicated.

 

Once the lampholder is correctly focused (or as correctly as modern lamps will allow!), the bracket secures to the inside of the canopy by means of a single screw - the far end of the bracket is held in place by a slot adjacent the cable entry hole.

 

The reflector was then reinstated.

 

With the bowl re-secured, the distribution of the refractor prisms begins to become apparent.

 

With the lantern powered up, the majority of the beam's flux is concentrated to the sides of the lantern, with the refractors displaying a more diffused pattern to the front and rear.

     

Lamp operation video:

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
239.4 0.04 5 10 49.8 0.52 4.98 -1.02 -17%

Fordac AC 850 | Thorn Beta 4


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