Hello , I put a 70 watt HPS light on my property , it seems to be working OK
except for the noise , sounds like a 60 Hz. buzz and is somewhat annoying ,
I had thought of removing the Xformer , Cap. etc. and locating them at a
lower position on my light pole and enclosing the components in a somewhat
sound proof housing , was wondering if this makes sense and also if my 600
v. cable could be used , the light housing would only contain the HPS bulb
and the photo sensor , wondering if anybody has had this problem and if so ,
what can be done .
Thanks
Phil L.
The ballast produces starting pulses of up to 4 kilovolts. If you need
to run a cable from the ballast to the lamp (the "bulb"), then the cable
between the ballast and the lamp socket needs to be rated for this
voltage. It also requires some suitable temperature rating for whatever
may occur near the socket - I don't know how much, but I doubt 95 C
cable rating is going to cut the mustard anywhere within a few inches of
the socket. The cable may need to be properly connected to high
temperature wires near the socket - see what is done for the existing
arrangement.
They also say not to make that more than (I forget how many feet, maybe
anywhere from 6 to 20 feet at most) so that capacitance in the cable
does not load down the starting pulses.
Keep in mind that modifying the sodium lamp fixture will invalidate UL
listing. That means possible grief, even from your own fire insurance
company, if a fire starts at a modified light fixture or one being used
other than as directed.
In case you are thinking of adding acoustric insulation around the
fixture, keep in mind that such may also be thermal insulation, making the
insides of the fixture hotter than before.
You could well be best off doing either of these things:
1. Tightening any screws at or inside the fixture *may* make it quieter.
2. Get a different fixture. Chances are, if you can find a 50 watt
metal halide one, it will illuminate as effectively as a 70 watt HPS due
to brighter rendering of many colored objects and a spectrum more
favorable to night vision than that of high pressure sodium.
Or, consider a suitable outdoor fixture for/with compact fluorescent,
preferably of higher color temp. 4100-6500 K, and preferably of such
design as to direct the light where you want it. Depending on fixture
directivity and your needs for such, you may outperform the 70 watt high
pressure sodium with a compact fluorescent anywhere from 26 to 55 watts.
CFL light with rated color temp. 5000 to 6500 K can have about twice as
much "effective nighttime outdoor illuminating power" (my words) as high
pressure sodium light with the same photometrics. This is because of a
spectrum more favorable to night vision and brighter rendering of many
colored objects than sodium light, and to a lesser extent even
improving upon most metal halide light in these areas. With CFL, you will
probably also get a nice quiet electronic ballast.
Maybe one of those Lights of America "Fluorex" fixtures will do you
well. I am aware that L.O.A. has gotten some bad press in Usenet for a
high rate of CFLs dying young, and my experience trying many of their
CFLs is that this is deserved. However, I do see several of their
"Fluorex" fixtures in use and doing fairly well, especially for their
price at home centers. If you get one of those, please try to get one
having a bit of directivity and direct the light to where you need/want
the light. That will get more light where you want it and/or allow you to
use a lower wattage, and also make the "dark sky" folks happier.
Also, I would be a little wary of claims of illumination efectiveness of
L.O.A. high color temperature "Fluorex" fixtures - my experience seeing
these in action suggests that they overemphasize a little the effect of a
spectrum favorable to visibility to night vision, and my experience with
many L.O.A. CFL products in general is a significant rate of
disappointment with their claims of light output.
However, I give fair chance of a L.O.A. "Fluorex" fixture "roughly
matching" or "mildly outperforming" effectiveness of an HPS fixture of
25-55% higher wattage and similar "radiation pattern" or "directional
characteristics".
- Don Klipstein (
[email protected])
