From: Ian Stirling
Subject: Re: Running high power mercury vapour lights at low power.
Date: Mon, 16 Sep 2002 03:00:13 +0000 (UTC)
NNTP-Posting-Date: Mon, 16 Sep 2002 03:00:13 +0000 (UTC)
User-Agent: tin/1.5.6-20000803 ("Dust") (UNIX) (Linux/2.4.18 (i686))
Mike Poulton wrote:
> On 15 Sep 2002, Ian Stirling said:
>> I have several 400W streetlights, that I'd like to use as biocidal UV
>> After the outer envelope is removed, should it be possible to simply
>> run it at 5% power simply by reducing the current? (I know the voltage
>> will rise)
>> (I have used it as a source to expose PCBs, but it's slight overkill
>> :) )
>> Is the life likely to be much extended, compared to running at nominal
> The life will be very much reduced (possibly to minutes, or a few
> hours). The lamps rely on high internal pressure and high wall
> temperature to prevent vaporization of the electrodes and condensation
> onto the tube. Additionally, they will have mostly an argon spectrum
> unless they get sufficiently hot to vaporize the mercury. This isn't to
> say it won't work -- it will light up and produce some UV, but it's very
> hard on the bulb and won't be very bright. I would suggest using a 175W
> bulb and balast from a residential floodlight. You can get them for
Oh well, in that case, I think I'll buy a UV tube.
The reason for the lower wattage is economic, and as I'd like to run
it 24*7, with expensive electricity, it doesn't make sense to use a much
> about $60 at Lowe's. Just break the envelope carefully and use it as
> the UV source. Make SURe you are not exposed to the light. It is not
> just UV, it's UVC and vacuum UV -- down to 194nm and shorter! It causes
> painful radiation burns, serious eye damage, and really promotes skin
> cancer. It also produces ozone, which needs to be removed by
Very nasty indeed.
Proper interlocking is pretty much mandatory, as is checking for light-leaks.
(I did the PCBs from outside a windowless room, switching on remotely)
http://inquisitor.i.am/ | mailto:firstname.lastname@example.org | Ian Stirling.
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