Revo 'Sol-d'Or' C15152

Lantern acquired in October 2009.

Thanks to James Wright for this lantern, which was originally situated in Lowestoft, Suffolk. Whilst the Sol-d'Or range of lanterns bear some resemblance to the Atlas / Thorn Alpha 1, they never managed to achieve the same level of popularity, and thus are rather rare these days, especially this type - the smaller version, for use on minor roads. This lantern became redundant following a lighting replacement scheme on the road it was installed on.

Photographs of some Sol-d'Ors in-situ in Lowestoft start off this lantern's documentation; these were taken by James Wright.

This photograph, taken towards the end of 2008, shows two consecutive Sol-d'Ors, without any new columns being installed alongside.

The foreground column in the first picture is seen again here, this time on the 18th September 2009. A new 5 m column supporting a WRTL Arc lantern will soon replace the Sol-d'Or. The replacement column has yet to be painted into the sage green colour commonly seen applied to lighting equipment in Suffolk.

This is how one of the outgoing brackets looked, following its removal from the column.

This attractive 1960s' lantern comprises a one-piece acrylic bowl and canopy unit that attaches to a very narrow aluminium shoe, and is secured by two toggles. The shoe has been painted the Suffolk sage green colour; however, this paint is now wearing off, revealing the shoe's original blue paint beneath.

The plastic (possibly a form of Bakelite) canopy has developed a crazing effect over its many years of service. The canopy is bonded to the bowl; this allows a good seal to be created in the lamp area - at least, that's the theory. Of course, the minicell attached to the canopy is not original to the lantern - this carries a date of December 1992 and is probably original to when the lantern was converted from time switch operation. Notice that the two bracket securing grub screws are located on top of the shoe - this is the only place that they could be accommodated as a result of the shoe's shape, however it does of course mean that the grubs are more susceptible to corrosion. Despite this concern, the concrete bracket was able to be removed, prior to the lantern entering the collection.

The two bowl securing toggles can be seen in this view. Whilst both of these are free, one is easier to release than the other. The underside of the bowl can just been seen - notice that there are signs of water ingress, probably as a result of most of the internal gasket having gone missing.

The underside of the bowl features dimples moulded into the plastic - the C13723/S's bowl features a similar effect.

With the toggles released, the bowl can be separated from the shoe section. An internal spine slides along a channel attached to the inside of the canopy. A small spring located about halfway along the spine prevents the bowl from being fully removed during maintenance (protecting the bowl from accidentally being dropped), though it can be raised, should the bowl ever need to be fully removed.

Just to prove that it can be done, here is the bowl shown completely separated from the shoe. The channel mentioned above can clearly be seen here. A common problem with these lanterns is that the toggles place stresses on the thin plastic around the bowl opening, which can lead to the plastic being clamped to eventually break away. This lantern is sadly no exception to this - the small hole on the right-hand side (as it appears here) is due to this.

Looking the other way, and the other ends of the toggles can be seen. This view shows just how thin the shoe area is. Asbestos-sheathed wiring connects the terminal block to the lampholder.

The inside of the shoe again - this time, looking at it the correct way up. The spine would have been painted glossy white originally - a small section of this can still be seen on the top, on the part that would normally be enclosed by the channel.

Click here to see the photographs relating to the restoration of this lantern.

Following the successful restoration of the Sol-d'Or (see above), preparations were made to get the lantern working. These photographs show how the lantern looked once it had been fully re-assembled.

An OSRAM 'SuperSOX' lamp (i.e. made at the company's own factory in Shaw, rather than at the Philips factory in Hamilton) was fitted.

The lantern was fitted to an AC Ford AC872 wall bracket on Friday, 27th November 2009.

Looking at the back of the lantern, the bowl toggles are seen in their 'engaged' position. The replacement gasket made these all the more effective at holding the bowl in position.

Thankfully, the lantern worked when powered up - and what a wonderful sight this was! I am therefore able to state that the lantern continues to "Sol-d'Or" on in preservation.

Lantern 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)
235.4 0.38 69 89 49.9 0.76 67.98

On a complete whim in April 2017, I decided to try one of my two 45 W OSRAM SOI/H lamps in this lantern; the Thorn AME.53182.T ballast that was already connected being suitable to run such a lamp, as well as 60 W and 85 W SOI/H lamps, and 40 W and 60 W SOX lamps (all of which were superseded by the 35 W and 55 W SOX lamp, respectively, in later years). Given that the position of the lamp support in this lantern allows a reasonable lamp overlap, even with the shorter 45 W lamp, clearly, Revo designed the lantern to accommodate the two lowest wattages of low-pressure sodium lamp that existed at the time. An equivalent to the 45 W size was never produced as a SOX lamp - upon the discontinuation of SOI/H lamp production, 45 W became obsolete; it is slightly longer than the 18 W SOX lamp, and the control gear for this modern wattage is not compatible.


Amid some trepidation, the bowl was re-fitted and the lantern switched on. The little lamp sprung into life immediately, filling the optical area with a gorgeous crimson light.


If anything, the lantern looked more suited to running the shorter lamp.


Warm-up was swift, and after only a few minutes, the majority of the arc tube was emitting the distinctive golden glow for which all low-pressure sodium lamps are renowned.


I wondered how many years had passed since this lamp had last been lit.


The area surrounding the upper electrode seemed to take longer to gain the appearance of the rest of the lamp - even after about ten minutes, this portion still had a high red content in its output. An issue found with SOI/H lamps was that the sodium had a tendency to migrate to colder portions of the arc tube, owing to the temperature not being uniform throughout the length of the lamp. This would leaving some sections devoid of sufficient sodium; hence, the issue here. Notice that a large pool of sodium exists at one side of the arc tube's u-bend. With some effort, this could be encouraged to return to the other side of the arc tube and (in theory) resolve the uneven light distribution.


Given that I didn't expect the 52-year-old lamp to work at all (ye of little faith!), I will overlook the rather uneven colour blend between both limbs of the arc tube.


With the bowl back in place, the now-warmed-up lamp's output became diffused by the dimply Perspex plastic, as well as the side refractor panels.


This video (not only) captures the lamp warming up within the bowl, but also, includes footage of the warm-up without the bowl fitted.

Testing the lantern again with the energy monitor made one revelation - namely, that the 15 F capacitor had failed!

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
245.5 0.6 75 147 49.8 0.49 72.18 27.18 60.39%

Or, perhaps not! After about half an hour of operation, the power factor was found to be much improved - in fact, the overall results were not all that different from when the results with the 35 W SOX lamp were obtained:

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
239.2 0.4 68 96 50 0.71 67.93 22.93 50.96%

Revo Prefect | GEC Z9484




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