CU Phosco P852

Lantern acquired temporarily in June 2018 but has, subsequently, been returned for use as part of Derbyshire's on-going LED conversion project.

The P852 LED lantern became a common sight on Derbyshire's residential streets from the mid-2010s onwards. Whilst always running 12 LEDs (a 6 LED version was available), the overall light output was governed by the running current that the driver was operating at - a higher current would, of course, lead to a brighter output but also a higher power consumption.

The all-aluminium P852 can be installed side-entry or post-top, depending on the type of rear adaptor that is fitted. Including the side-entry adaptor, the lantern measures 634 mm (2.08 ft) in length, 89 mm (3.5 inch) in height and 130 mm (5.11 inch) in width, making this a very slim design. A length of flexible cable is supplied pre-wired to the lantern.

From above, the straightforward design of the lantern can be appreciated. The wiring is located behind a rear panel (which is secured with two hexagonal bolts) that also serves as the mounting point for the NEMA photocell socket. Heat sinking fins at the front of the lantern, along with two air gaps, allow any heat generated by the LEDs to be dissipated into the atmosphere.

The Zodion NEMA socket itself was manufactured in June 2017.

The underside of the lantern is home to two identification labels - one (the smaller of the two) being the Phosco product label; the other being the identifier label for use by the Council, in order to identify the lantern from the ground - the code translates as follows:

C - CU Phosco

13 - Wattage

P5 - Intended lighting class

D - Dimmed to 75% output after 21:30 and to 50% after midnight until 05:00, when the output returns to 75%, and then to full output from 06:00 until dawn. The black button-like object below the Phosco logo serves as a means of ventilating the lantern interior.

The smaller label indicates that the components were assembled into something resembling a lantern on the 4th January 2018.

The twelve LEDs are arranged in two rows of six.

The lens can be removed by taking away the eight screws that hold it in place. In theory, the beam distribution could be reversed, as the lens fits both ways around.

The individual lenses are arranged in such a way that ensures that the beam is at its strongest to the sides of the lantern, although a slight amount is cast forwards too. Taller lenses behind each LED ensure that backlight is kept to a minimum, however.

The spigot entry is common to the P850, P851 and P852, and this type can accommodate brackets with a maximum diameter of 42 mm. An adaptor of this same diameter is housed within the entry, in order that the two 5 mm grub screws used in securing the lantern to the bracket are not too short to grip narrower (typically, 34 mm) bracket diameters.

Two 6 mm grub screws attach the spigot entry to the lantern. Loosening these allows the lantern tilt to be adjusted from -10 to +10 degrees. With the spigot entry separated from the lantern, the teeth that secure the lantern to the desired tilt are visible. The pink substance that is visible is lubricating grease.

Removing the two bolts from the top panel allows access to the internal wiring.

A Philips 'Xitanium' driver operates the LED cluster. This is pre-programmed to the required dimming regime, although its programming can be altered by means of a 'DALI' input. The driver offers considerable flexibility; being able to drive LEDs at any current between 300 and 1050 mA.

Removing a few screws allows the driver (and its half-length gear tray) to be taken out of the lantern. The wiring into it employs push-in connectors, allowing rapid replacement in the event of driver failure, although in practice, I can imagine the lantern being replaced in its entirety - such is the disposable nature of modern lanterns.

Two further labels are attached to the inside of the lantern; the left-hand one providing the dimming information, whilst the right-hand label is a duplicate of the one seen on the lantern exterior.

The lantern was, subsequently, attached to a wall bracket and a plug fitted to the cable. After being switched on, the twelve neutral-white LEDs sprang into life.

From the side and just above the horizontal, the individual lenses could be seen.

Owing to the lens construction, the lantern glare is vastly reduced when viewed from the back.

From the front, very little of the light source is visible.