GEC Z5698U

This lantern was the one and only lantern to be removed in my presence during my work experience with Derby City Council's street lighting department. I was working with Jeremy (someone whom I only thought that I'd know for the duration of the work experience week - which obviously was not the case as things turned out!) on Wednesday, 14th May 2003, and one of the job sheets we had was to repair this particular lantern - it had been reported as being unlit. We went up to have a look and soon noticed that the lantern had a few cracks in the bowl, and was showing signs of water ingress, so the decision was made to replace it. Being a post top lantern, there was a limitation as to the sort of replacement lantern we could use - really, the only other post top lantern used regularly in the Derbyshire area is the Thorn Gamma 6, and we didn't have any in stock at the time, so a small outreach bracket was attached to the column, and a Thorn Beta 5 was fitted. Using this lantern probably actually improved lighting levels along the road - post tops tend to spread more of the light at the height at which the lantern is mounted.

Saving one lantern from a column is always fantastic. Saving the lantern that replaced a lantern that entered a Collection (are you still following?) must be a very rare occurrence indeed. However, this is exactly what happened here - the Beta 5 that replaced this Z5698U was itself replaced in April 2010, due to the commencement of the Derby Street Lighting PFI in Mickleover. This lantern and its associated column (60556) were earmarked for replacement, and so I decided to try to save this lantern for the Collection, owing to its history being known. Thankfully, I was successful in acquiring the lantern after the column had been disconnected, and so, on Friday, 7th May 2010, I picked it up from the depot. Photographs of the lantern can be seen here.

I decided to keep this lantern, as it has always been one of my favourite lantern types, namely because such lanterns were used on a footpath behind the house that I lived in when I was young - and as luck would have it, my bedroom was on the back of the house, and you couldn't look out of the window without seeing at least one Z5698U! I loved watching the lamp warming up, and often wondered why the lights at home did not do the same! I also wondered how the lantern switched on/off every day, but I seem to remember the 'light sensor' principle being explained to me very early on! I reckon that this lantern was the main reason for my interest in street lighting today.

A few years before we moved to the present house, the lantern was changed for a Gamma 6 - what a pity I didn't collect back then!

In March 2010, I managed to acquire this Gamma 6 for the Collection, along with the sole-surviving Z5698U further along the footpath (also visible from my window). Pictures can be viewed here.

The following is the inventory record for this installation. This record is as it was in 1997, when Derby City Council took control of its own street lighting repairs from the County Council, and when the Z5698U was still fitted, of course. Therefore, any changes made after this date (including the change of lantern type in 2003) are not shown.
Unique Number: 60556 Location: O/S NOS 5/7
Postcode: DE3 5NT Road: WENLOCK CL
Road Number:   Parish: MICKLEOVER
Sequence Number: 3 Patrol: Y06
       
Lamp Type: SXPL3 Wattage: 35 Watt Control Type: PE1E
Lamps/Lantern: 1 Lanterns/Unit: 1 Control Setting: 4
Lantern Type: PT Lantern Manuf:   Control Gear:  
Height: 5  m Support Type: TS TUBULAR STEEL - PAINTED
Bracket Proj'n.:    m Support Finish: P PAINTED COL/SIGN/PILL/GANTRY
Bracket Type:   U/G or O/H: U UNDERGROUND
Board Code: E76 Status Code: 0 USUAL / NORMAL
Service Owner: A Is this lamp/sign an Isolation Point ?: N
EB Order number:      
No-supply sheet: 0 Isol Pt:   / Circuit:   / Seq:  
               
               
 

The lantern as received - this is actually a reasonable example - most in the area are in need of a good clean. This lantern is not fitted with a NEMA socket as it was group switched off another one down the road. The bowl is yellowed, but not as badly as it appears in the photograph - the SGS 204 was on when I took the picture.

 

As with the Z5670, the bowl on this lantern can only be removed by first of all removing the canopy. When new, the two wires going up to the lamp would have been secured to the support poles with cable ties. The gear is all mounted in the base of the lantern, under the white reflector plate.

As with many GEC 35-55 Watt SOX products produced in the late 1970s until the late 1980s, a Z1616 ignitor-ballast and Z1757X capacitor make up the gear, with the ballast carrying the date code 'MD' (April 1980), and the capacitor having been made during week 18 of the same year, which is the 28th April - 4th May. Since this picture was taken, the Z1616's ignitor circuit failed, requiring the installation of a Tridonic ZRM 36 ignitor in the narrow space between the capacitor and the ballast.

 

The lantern's canopy was heavily covered in fingerprints due to the grease from fingers reacting with the paint - this seems to happen to spray painted surfaces if they are continuously left outside for long periods.

 

Looking into the canopy shows the hinge mechanism - the internal rim stays fastened to the lantern; the outer section hinges through 180 degrees.

 

A slightly blurred shot of the bowl - the reason for its length is that the Z5698U could run both 35 Watt and 55 Watt lamps (see below), and so provision for accommodating the longer lamp was required.

Despite the yellowing on the bowl, the lamp can still be seen inside. Had this been a SON or mercury fitting, this would not be possible. The vertical refractors on the bowl do a good job of diffusing the light outwards and downwards.

Very little work needed to be done on the lantern to get it looking something like it must have done when new - the only thing that could not be sorted was the bowl's yellowing, but as can be seen here, it is not too bad.

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
241.1 0.23 49 55 49.8 0.88 48.80 13.80 39

A replacement bowl was found (Thanks to fellow collector Simon Brown!) and duly fitted on Sunday, 7th September 2008. The bowl is much clearer than the original, although it still appears to be slightly yellowed in the picture below...this is simply due to the yellow walls in the lantern room!

Following the acquisition and restoration of the second Z5698U in 2010, this lantern was converted to 55 Watt SOX on Wednesday, 28th July. As far as I am aware, this option was never specified for the Z5698Us in Derby, although I had previously photographed one such example, which appeared to have accidentally been fitted with a 55 Watt lamp during a clean and change session.

A 1990s' OSRAM SuperSOX lamp was fitted - now the reason behind the lantern's length becomes obvious!

The lamp, being new, took approximately half an hour to fully warm up - the picture below shows it after twenty minutes.

With the bowl and canopy reattached, the lantern produced an altogether different outward appearance.

Testing the lantern again 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
243.8 0.35 66 85 49.8 0.76 64.85 9.85 18

Lamp warm-up video:

I did not take any pictures of the lantern before removal, so this is actually a combination of two pictures - the first being of the column with Beta 5 replacement (which can be seen below); the second being of another Z5698U nearby. Both pictures were taken within a few minutes of each other, in order that the sun would appear in the same position for both.

 

The Beta 5 that replaced the Z5698U. Jeremy has written the date the lamp was installed together with when the lantern was connected to make the guarantees work! (Engineers are supposed to date everything they install, in order that, if a fault develops or a lamp wears out before the guarantee has ended, the money for the guarantee can be retrieved. Lamps that have been vandalised do not count - and so every time a lamp is vandalised, no money can be obtained and the council has to buy new lamps.) Notice Jeremy's initials by the Beta 5 label (JPS) The other initials are those of the person who helped in the lantern's installation - me! (MB) So this lantern is half mine by rights if it's ever removed!

The lamp is a Philips 'Osram' lamp - the photograph was taken on Monday, 16th June 2003, a 'boiling' day! I can only think that the aluminium canopy would make the lamp pretty warm - if switched on, it would probably be at full power instantly!

GEC Z9464 | Thorn Beta 5

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