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