Thorn Beta 79

Lantern acquired in June 2004.

This lantern is fairly new; however, the column it was on had been knocked over, and it was decided that the new column would be fitted with a new lantern, meaning that this one was made redundant. The 100 Watt version of the Beta 79 was only used in a few places in Derby, as was the 125 Watt mercury version - the 70 Watt version was far more common but even then, was not used for general 'street' lighting; instead, most examples were seen on footpaths and in car parks.

The similarities to the Alpha 8 are shown here.

The tops of the bolts used to hold the plate that secures the bracket can be seen on the canopy.

The deep bowl version of the Beta 79 has quite an interesting refractor/diffuser below the lamp, but the shallow bowl does not have this patterning and is completely clear.

As the lantern is 100 Watt, the lampholder is at the front of the lantern instead of in the middle like for the 70 Watt version. A label affixed to the rear of the optic states that the lantern was made during Week 15 of 2004 (the 5th - 11th April).

The lantern's gear is mounted on the back panel. At some point, the original Tridonic ignitor has been replaced with a Philips equivalent - the SN58 (the wiring diagram for this is here), but other than that, it is all original.

A close-up of the gear components.

The lantern was mounted to an AC Ford AC872 wall bracket on Friday, 12th August 2005. It was then wired up and switched on.

As the lamp is not surrounded by a reflector, some of the output is emitted through the GRP canopy.

The positioning of the bowl refractors distorted the lamp to the extent that its shape was no longer recognisable.

Lantern warm-up video:

GEC Z5670 | Revo Prefect

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