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Intercom noise caused by lamps

When the outside lights in this apartment house come on at night by photocell control they cause a loud buzzing noise in the buildings' intercom system. These lights are the type that come on dim and warm up to full brightness over several minutes. There are two large lighting units mounted on the front of the building and three smaller units mounted in the back. One of the large units is inoperatve in the front and one small unit is also not working in the back. Are these what are called "high pressure sodium"? Are these known to generate RF interference? Is there a ballast in these things, and if so would a defective bulb cause the the device to radiate energy into the air instead of the load? Can someone please explain how these work and what might be the most likely cause of this problem? Thanks for any opinions on this. Lenny Stein, Barlen Electronics.

Reply to
captainvideo462002
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It's impossible to say without a description of the bulbs and the light they emit. They could be metal vapour lights like Sodium, Cadmium or Mercury, but they could also be HID lamps.

Dave

Reply to
Dave D

is it a wireless intercom or wired?

Mark

Reply to
Mark

If it's a wireless system I'd say you're out of luck unless you replace the lights or get an intercom that can filter out the interference.

If it's a wired intercom, You may need to make sure the lights and the intercom are fed their AC power from different branch circuits. Also, you may need to replace the wiring between the intercom panel and the individual receivers with shielded wire.

But first try something simpler - make sure all intercom wire connections are clean and tight, and if there are any ground connections, make sure they are secure.

Reply to
Jumpster Jiver

Are these the crappy Lights of America wall packs with electronic ballasts? A friend of mine had several of those and they failed one by one, the ballasts were very cheaply made and it wouldn't surprise me if they produced a lot of RFI.

Most HPS uses magnetic ballasts, those shouldn't cause interference, except if a lamp is failed the igniter will pulse repeatedly and cause a ticking sound to be picked up by nearby audio equipment.

Reply to
James Sweet

Huh? HID is a broad category which covers high pressure sodium, mercury vapor and metal halide lamps. There's no such thing as a cadmium vapor lamp, at least not outside of specialized lab uses.

Either way, all HID lamps operate in a similar manner and the ballasts are also very similar (though their characteristics must be a proper match for the lamp.)

Reply to
James Sweet

I meant metal halide. Note the time I posted ;-)

Dave

Reply to
Dave D

We found that the problem was caused by a defective lamp. It was either arcing (although that wasn't evident) or the fact that there was no load to dump the energy into was the problem. In any case a new high pressure sodium lamp fixed it. I learned something today...... Lenny Stein, Barlen Electronics.

Reply to
captainvideo462002

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