LED lighting policy is a peculiar one. Southampton installed some LED street lighting, and even though each lantern consumes 45w the light output is noticeably dimmer than any other street lighting in the city, including 42w PL-T lanterns, which consume about 42w in total and are at least 50% brighter, and 45w CosmoPolis, which consumes about 52w in total and is over 100% brighter....this is what puzzles me about Bolton Council's decision. They are changing their current policy of 45w CPO (I assume that means CosmoPolis!) spaced at 24 metres / mounted at 5 metres to 18w LED lanterns spaced at 26 metres / mounted at 5 metres.
It will be years before LED, or even the new breed of fluorescent lighting reaches Colchester (we still like our 35w SOX, and 70w SON near the middle of town!) so I cannot guess how efficient an 18w LED lantern would be. But the sheer drop in wattage rings alarm bells for me, especially for white light (the efficiency of which has historically lagged behind non-white light).
A particularly troublesome housing estate in Clacton recently had its lighting changed from 35W SOX to Phosco P700s sporting white light (presumably the 35w CDM), but the few 35w SOX casual replacements that have already sprung up on the estate seem to be brighter than their CDM neighbours. This could be a trick of the light however - the SOX casual replacements are the traditional non cut-off type, can be seen from the end of the road and illuminate the surrounding houses, whereas the P700s are cut-off and only illuminate the patch of road under the column.
Surely 18w LED, no matter how well directed, would be really dim?
My brother's Royal Air Force base recently had its Beta 2s replaced with LED lanterns, but I have not had the opportunity to view them at night yet!
Originally Posted: 20-10-2009, 11:18:06 pm