My friend has a 100 watt mercury vapor security light on her garage that for the
most part won't turn off. she's replaced the bulb, it needed it anyway, but the
guy doing her handyman stuff says the sensor has to face north. the wall the
light is mounted on faces east, north faces a 12 to 18 inch roof overhang. seems
like it would make more sense to face east or even south east, but she isn't
sure if the sensor is able to be rotated and since she has a new one to put in
with what looks like a weird electrical outlet three prong plug, I doubt that it
can be rotated. Any recommended fixes?
Does sensor have a shade like camera shade on it and/or is there an
adjustment for setting the sensor sensitivity. My El Cheapo 9.99
security flood light has two adjustment. sensitivity, turn off delay,
If there is no adjustment try blocking the sensor opening partially with
piece of black tape like a shutter. May have to fiddle with it few times.
On Oct 6, 7:22 pm, "Malcom \"Mal\" Reynolds" <atlas-
Did it ever work? If so, then it would sound like it's
the photoelectric sensor that's kaput. I don't buy the
idea that it has to face north. If anything that would make
the light go off easier, because more light would hit it.
It may give the best result but it has nothing to do with
the light not turning off, which is the issue at hand.
Which direction receives the least light? You have
some half-assed handyman attributing the fact that
it won't turn off to the fact that it's facing north. I
True: but any orientation that allows it to "see" liight/dark without
interruption is acceptable. North (magnetic north) is simply used to make
sure east & west times correspond properly wthout a slight difference in
light receieved otherwise.
have to agree; the sensor is the major component and as long as the bulb
contacts the internal contacts, it's positioned where light isn't shaded,
sensor is properly wired, then it should work. In the 30 years here we've
only ever replaced the sensor one time and had to reset the screws to hold
the reflective shade in place. Beng rural here, there are thousands of them
around and they all have the same records of longevity, best II can tell.
A couple years ago we switched to a sodium vapor bulb/sensor and now we
only put iit on for guests arriving or during a storm, especially snow
Installation recommendations for dusk/dawn controls are that they face north
so that direct sunlight doesn't fall on the photocell. That gives the best
on and off times -- not too dark, not too light. The sensor with the
strange plug is a standard street light type. It locks into place and then
either the socket or the sensor head is designed to be rotated.
In your friend's situation, aim the sensor opening toward the north and then
rotate it until it "sees" a bit of sky.
Mercury vapor ballasts and lamps are now obsolete and will no longer be sold
once existing stocks are gone, but they last a long time -- typically 24,000
or more hours. Dusk-to-dawn operation is about 4,000 hours/year.
*Put the new sensor in and see what happens. It sounds like it is a
standard twist lock type. Plug it in and rotate it until it locks in place.
Sometimes there is a shade that can be adjusted to the proper direction.
Could be a cruddy switch. G.F. has a motion-sensing security light in
the carport that was staying on. There were a couple of slide switches
and a potentiometer on it. The pot adjusts sensitivity, and the slide
switches adjust ON time and override the motion-sensing feature so it
can be manually operated. At any rate, I "fixed" it by exercising the
switches and pot.
Your friend's is apparently a dusk-to-dawn (light sensing) rather than
motion-sensing, but either way you'll likely find one or more switches
on the sensor that haven't been touched in years. Exercise them, spray
'em with WD-40 or contact cleaner, or replace. Of course, the sensor
window could be getting cloudy, or the sensor could be failing for some
other reason, but the switch manipulation is a good first effort.
as of this moment, it appears that putting a replacement sensor has solved the
problem. I'm a little leery of saying it's cured because she's got another set
of security lights that get "cured" and work for a bit and then decide they
But thanks to everyone for the help. I didn't actually see the installation but
did see the replacement sensor and it didn't have a "shad" or adjustment
On 10/7/2012 2:39 PM, Malcom "Mal" Reynolds wrote:
Yah, I feel your pain. It has been my experience too that the
consumer-grade motion sensors and photocells purchased from McLowesDepot
are garbage. Seems they last a few months and then die. I gave up on
them but maybe a sensor from an electrical supply house might last longer???
On 10/6/2012 5:22 PM, Malcom "Mal" Reynolds wrote:
If the light stays on the only likely culprit is the sensor, which you
They should face north because direct sunlight on the sensor tends to
kill it. It won't last as long depending on the sunlight exposure.
I don't remember how it works, but the top can be rotated relative to
I hope the installer figured out the plug is twist lock and should be
inserted and twisted clockwise.
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