Local WRTL/Industria Libras

The 24 W and 36 W versions of the Libra replaced sister lantern the Arc as the standard Derbyshire Maintenance lantern for 5 m columns in the early 2010s. 24 W versions were generally reserved for footpaths or especially narrow roadways, whilst 36 W versions were used for all other roadways.

The replacement column at this location in Milford saw the installation of a 24 W Libra; the road is narrow, and the output from the 24 W lantern would be sufficient.


This 24 W example located on an un-surfaced footpath in Swadlincote replaced a Stanton 1805 concrete column in late 2013. The new column is mid-hinged, in order to facilitate future maintenance as access with a vehicle, although not impossible, is difficult.


The 24 W version uses the same lantern body as is employed with the 36 W version - notice that the shorter lamp does not fill the entire reflector area.


These 36 W examples are from the same estate in Swadlincote that the above example is on - again, all were used as replacement lanterns on new columns after removal of the 1805-type columns on the estate.


The longer lamp can be seen here.





This Libra in Horsley is fitted with an SS9-DLS part-night photocell.


Rather than operating part-night, this Libra in Etwall was pictured operating constantly; the part-night photocell having failed.


At least, this allows the working lamp to be seen.


The reflectors are angled in such a way that they have no effect on the light output directly beneath the lantern.


The 1805 column that the following installation replaced was in virtually original condition "at the top" when removed - it retained its concrete bracket, and still supported what was likely to be its original lantern - a remotely-geared Philips MI 50 35 W SOX lantern complete with P42 two-part photocell. The only indication that time had elapsed since the column's installation was the fitting of a base sleeve at door level; suggesting that this particular column was suffering from the structural issues that this type of column is notorious for having. Oddly, the new column is positioned with the lantern pointing 90 degrees from the direction that the old lantern faced, meaning that it concentrates less light on the actual carriageway and more on a communal parking area for some sheltered housing. This does, however, allow a more unusual view of the lantern.


This 36 W example in Duffield replaced a defective Philips MI 26 35 W SOX lantern.


The length of the new lantern almost matches the length of the bracket!


This 36 W Libra has been retro-fitted to an ELECO 'Silverline' aluminium column located adjacent the busy A632 in Kelstedge; it replaced a GR 501 lantern in 2013/4.


Viewing the installation from a slightly different angle reveals the rather severe upward tilt of the bracket.


A twin bracket arrangement exists in Draycott. The 1805 column that this setup replaced was itself fitted with a twin bracket and Thorn Beta 5 35 W SOX lanterns.


The narrow 34 mm diameter bracket arms look particularly spindly when entering the lanterns; this is because the lanterns cater for bracket diameters of up to 60 mm - a Continental size that is relatively uncommon in Britain; at least we are able to maintain an identity for some things!


This new housing estate in Pleasley is the only place in Derbyshire where 36 W Libras were proposed for the new development's lighting; the examples seen above were all one-for-one replacements for lighting on existing roads.


Included with every Libra lantern are a couple of rigid black plastic inserts that are intended to reduce the amount of forward and backward light cast by the lantern. These are optional and are generally not fitted by contractors. The inserts clip into the sides of the bowl. Additional inserts are available in situations requiring extra light control.


A slightly unusual variant of the Libra is the Libra-X lantern; this is specifically intended for use in illuminating pedestrian crossings. The picture below shows two such lanterns illuminating a Zebra Crossing in Swadlincote. The lanterns are attached to the spigots of special 6 m columns that also act as a support for the Belisha Beacon unit; the type seen here is the "Zebrite" type, incidentally.


The lamp is offset in this version of the lantern. This provides the necessary asymmetric light distribution that ensures that the majority of the luminous flux produced is concentrated on the crossing itself.


The offset lamp is more apparent in the example installed on the opposite side of the road. A Zodion Super6 photocell is fitted here.


Long before the installation of these columns, I noticed on Sunday, 18th April 2010 that three Libras had appeared on the service road leading to Derby's Kingsway Retail park. The lanterns replaced damaged Thorn Alpha 4 / Philips MA 90 90 W SOX lanterns. The service road is apparently not adopted by the City Council, and maintenance on the lighting is probably the responsibility of a private contractor. I am surprised that Libras were installed on the existing columns, but at least they're a little different to the norm!

Two of the three installations are photographed below; I assume that the lanterns are fitted with 80 W PL-L lamps:





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