On Sunday, October 14, 2012 1:41:45 PM UTC+1, Martin Brown wrote:
On 14/10/2012 11:20, Fred wrote:

Hi,



Whilst helping the relatives have a spring-clean, I found an old

exterior light, it is rather like a street lamp, so more

commercial/industrial than domestic. It looks as thought the fitting

is largely made of aluminium, so I was hoping to take it to the scrap

man.



It is probably worth more to someone who wants an HPS lamp and fitting!

(at least if it is functional)



The old magnetic ballasts are not as good as the latest solid state in

terms of efficiency but they are still pretty good.



I think they may be sodium lamps as the bulbs look something like a BC

version of this:

http://www.screwfix.com/p/sylvania-h...ges-250w/90688



I notice the description says "golden white" whatever than is! I

thought they were orange.



Golden white or peachy white is the colour of a typical HPS (high

pressure sodium lamp) - you can get sort of lemon yellow white. They

strike yellow and rapidly turn creamy whitish.



The orange ones are low pressure sodium and emit more or less all their

light in the sodium D-lines. They strike red and gradually turn yellow

as they warm up. They are preferred street lighting in the vicinty of

professional optical observatories. Declaring an interest here as I sell

sodium light blocking filters to amateur astronomers:



http://www.nezumi.demon.co.uk/nonad/spectra.htm



Shows the spectra of the most commons street lamps and the effect of

various astronomical filters on them.



Inside the fitting is a large (in terms of size, not capacitance)

capacitor and a heavy metal ballast. The ballast is a sealed unit.

Does it have an iron core? Is that why it is so heavy? I'm just

wondering what bag to throw it into to take to the scrap yard. Do I

throw it in with all the steel? Perhaps I should angle grind it open

to see what's inside?



You might want to keep it as an outside light if it is actually working

- they are far more energy efficient than other sorts.

Yes - but 250w of 120lm/W or so is a monstrous amount of light, around 30,000 lumens. Good for a greenhouse.


NT