Thorn 'SONPak 7' OT 70.T

This is another 'nostalgic' fitting for me - a local building used several of these floodlights for internal architectural lighting, and in my younger days I used to watch the lamps switch on and warm up when the lighting was required. I had previously thought that the fittings were a larger version of this type; however, I have subsequently found strong evidence that suggests that no such fitting existed, so the installed examples must also have operated 70 W SON lamps, and only appeared larger due to the perspective at which they were seen at. The 'SONPak' range of floodlights from Thorn first appeared in the early 1980s (indeed, the building that they are installed in opened in 1982), and the name still exists today, although the modern equivalents do not seem to be of the same quality as their predecessors were. This is an earlier version of the SONPak 7 floodlight already documented in the collection; evidenced by its aluminium construction, as opposed to GRP, as later versions were made of.

The lamp is situated within the centre of the floodlight's reflector, and provides an asymmetrical light distribution. The dimples embossed on the sheet aluminium of the reflector are not as pronounced as they are on the later version of this floodlight. The cable entry hole is centred in this fitting, but is offset on the later version.

When new, the aluminium bodywork of this floodlight would have been painted black; this has completely disappeared on this example, and it is starting to wear away on the floodlight's fixing bracket as well. This will be remedied in due course.

The technical information for this floodlight is provided on a thin plate that is pop riveted to the reflector. The later version of this floodlight saw the plate replaced with an adhesive label attached near the cable entry hole.

A Thorn-branded SON-T lamp was included with this fitting. It carries the date code of '04', which means that it was made in April 1982. A date stamped on the side of the ballast suggests that the floodlight was produced in the same year; presumably, this lamp is therefore original.

A single screw secures the reflector; with this removed, the reflector can be taken out of the fitting - though the length of the lampholder prevents it from working completely loose if the screw is absent. The insides of the floodlight still retain their black paint finish.

The gear tray tucks into the recess beneath the reflector during normal operation, and is secured with two screws at either end. In theory, the screws would not need to be removed during the floodlight's installation, as the connector block (along with the ignitor and capacitor) is positioned on the side of the gear tray that is visible when fitted.

A Thorn G53320.T ballast is fitted to the other side of the gear tray.

The floodlight body and fixing bracket were then sent away for a much-needed repaint. The components returned on Wednesday, 3rd November 2010 - in their restored black finish.

The floodlight was then reassembled and installed in the collection; right next to its 1990 equivalent. The difference in the dimples on the two reflectors is very obvious here.


With the two floodlights operating, the effectiveness of both reflectors is shown - the older floodlight appears a little more glary than the newer example is; perhaps this is why the reflector patterning was changed. Incidentally, the 1982 lamp took over half an hour to fully warm up - it has obviously seen a great deal of use.

How's this for a floodlighting scheme - having the fittings illuminate a street lighting display!

Lamp warm-up video:

Testing the lantern 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 (W) Percentage Difference
238.1 0.49 75 117 49.9 0.64 74.67 4.67 7%

70 W SONPak Floodlights in the Collection

1982 1983 1985 1987 1990 1993 2000
Installation and Servicing Instructions

Ivela Stage | Thorn 'SONPak 7' OT 70.T (1985)




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