On Wednesday, March 13, 2013 2:28:00 AM UTC, Arfa Daily wrote:
Has anyone got any long-term experience of LED street light replacements ?

They've just started replacing all the lamposts in my street, with a lot

fewer - and 2 metre taller - lamposts fitted with LED luminaires. We had a

circular from the contractors / council come through the door, which made

some claims about how much money they had already saved by switching off

half or more of all the lights in domestic streets, and just about all of

the lights on the main roads. They then went on to make some further claims

about how much more money they were going to save as a result of fitting

these new LED based lights. Both myself, and my neighbour, who is an

industrial electrician of many years experience, think that the claims being

made are fairly outrageous, and that the numbers, as presented, don't stack

up. The previous lights were low pressure sodium, and when the guy came to

replace a faulty lamp in the one between our houses, my neighbour asked him

what the power rating was. It was 35 watts, which really isn't a lot. OK, I

know that there will be some losses in the ballast, so let's add another few

watts to that and call it 40 watts all in.



Looking on the 'net, it seems that the LED equivalents start at about 28

watts, with a further 9 watts lost in the driving engine, so 37 watts, which

doesn't seem like a whole bunch different from the sodiums that we had

before. Apparently, the new ones are going to dim down at 2 am, so that

will, admittedly, save a bit more, but it still seems to me that the figures

are being presented in a less-than-straightforward manner, which seems to be

the way of all government propaganda, both central and local, nowadays.



Last night, they switched on some of the new ones at the other end of the

street, so tonight, I drove round to take a look. My neighbour said that

when his missus came home last night, she reckoned that they had dazzled

her. I could see what she meant. They were actually quite unpleasant to

drive under. It seems that they have given them a wide dispersion angle in

an effort, when coupled with the extra height over the original lights, to

fill in the pools of gloom left by setting fewer of them further apart. The

result is that they shine down into your face from quite a distance away.



They also claimed that night time colour rendition would be better, because

the replacement lights were going to be white. Well, they *are* white - sort

of. But actually, the light is quite a creamy colour. But setting that

aside, I really don't see why night time colour rendition is of any

importance, over the fact that one of the main reasons that sodium lighting

was first introduced, was because it improved visibility in fog by a huge

amount. I can still remember driving in fog when street lighting was

predominantly by conventional linear white fluorescents, and it was a much

improved situation when the yellow sodium lighting was introduced.



I'm interested in any thoughts, facts, experience or observations that

anyone might have.



Arfa

A bit late to this thread, but we have noticed that you cannot distinguish between a bright white LED street lamp reflecting of something and a vehicle coming down the road but just out of sight.
This actually causes one to be slightly more cautious about what might be approaching, but equally it could distract your attention from something else that mattered.
Simon.