120 volt lighting contactors humming loudly

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patricknola

Electrical contractor/Generac Dealer
Location
new orleans, La, United States
Occupation
Electrical contractor.
Hey Guys, I am working for a guy and we are wiring a small retail strip mall new install. We have lights running around the outside of the building and the contactors for the lights are mounted next to the panel outside. We have 3 new 120 volt square d general purpose contactors for the lights and everything is working fine except the contactors are humming really loud. if we press on the contactors they humm less. Otherwise they work fine. Any insight?
 
patricknola said:
Hey Guys, I am working for a guy and we are wiring a small retail strip mall new install. We have lights running around the outside of the building and the contactors for the lights are mounted next to the panel outside. We have 3 new 120 volt square d general purpose contactors for the lights and everything is working fine except the contactors are humming really loud. if we press on the contactors they humm less. Otherwise they work fine. Any insight?
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What do you mean...mounted next to the panel outside? Just curious.

I wonder if you have vibration hum. Are they mounted in an enclosure, screwed in with tek screws? Coarse threaded, perhaps?

Maybe try some finer threaded screws and rubber washers to cushion any vibration?
 
Do you have a part # for the contactor?
What lighting technology and what load do you have on it?
 
It almost sounds like relay chatter. Like iwire said double check you have the right voltage to the coil. I'd read voltage across the coil with the contactor pulled in. Look for a loose conductor, double check your neutral. Something is keeping the coil from pulling in and seating the contacts tightly.

It's weird that it's effecting all 3 brand new lighting contacts. Identify what variables are common to all three contactors and start going through them. It's probably something simple.

Are they on three separate photocells? Is there and H O A you can put in hand?
 
120 volt lighting contactors humming loudly

Yes, the contactors are showing 120 volts, we tested each one, The are mounted in a nema box on the outside of the building with a chase to the panel where the circuits land. Each one of the contactors does vibrate at a different intensity, which means one is loudest, one is softest and the other's humming is of medium intensity. thanks
 
patricknola said:
Yes, the contactors are showing 120 volts, we tested each one, The are mounted in a nema box on the outside of the building with a chase to the panel where the circuits land. Each one of the contactors does vibrate at a different intensity, which means one is loudest, one is softest and the other's humming is of medium intensity. thanks
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This is a classic case of "mis-harmonics"

To repair, just loosen one, tighten one, and leave one as is.
Now they are in "harmony"!:D
 
patricknola said:
Yes, the contactors are showing 120 volts, we tested each one, The are mounted in a nema box on the outside of the building with a chase to the panel where the circuits land. Each one of the contactors does vibrate at a different intensity, which means one is loudest, one is softest and the other's humming is of medium intensity. thanks
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Has any one tried tapping it with a screw diver handle? If that doesnt work, call the manufacture. I am sure they have a solution.
 
patricknola said:
Yes, the contactors are showing 120 volts, we tested each one, The are mounted in a nema box on the outside of the building with a chase to the panel where the circuits land. Each one of the contactors does vibrate at a different intensity, which means one is loudest, one is softest and the other's humming is of medium intensity. thanks
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I don't want to be a pain but when you say they are show 120 volts what does that mean?

Did you test the coil input voltage from line to line, not line to ground while the coils where energized?

Can you see that the coils themselves are labeled 120 60hz?

Don't trust the package labeling or even the label on the contactor, look at the coil itself verify they did not install the wrong coils

If all that checked out and they still hum I would return them.


Now one more question, are these really lighting contactors or are the definite purpose contactors?
 
mgookin said:
Do you have a part # for the contactor?
What lighting technology and what load do you have on it?
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???

This is the easiest place to start.
If you're pulling 50A on a $6 contactor, that's your answer.
Did you build this out of parts you found on the truck or did an engineer spec the build?
 
iwire said:
I don't want to be a pain but when you say they are show 120 volts what does that mean?

Did you test the coil input voltage from line to line, not line to ground while the coils where energized?

Can you see that the coils themselves are labeled 120 60hz?

Don't trust the package labeling or even the label on the contactor, look at the coil itself verify they did not install the wrong coils

If all that checked out and they still hum I would return them.


Now one more question, are these really lighting contactors or are the definite purpose contactors?
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Or you can call me, I will listen to them. Give a subjective opinion and declare they are OK.
Have you noticed that crickets aren't as noisy as they used to be?

Low end contactors are a problem.
 
iwire said:
Now one more question, are these really lighting contactors or are the definite purpose contactors?
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OP said "general purpose "..... I'm pretty sure these are DP contactors they're using for lights.

Some definite purpose contactors are just going to chatter like that. I've shoved little pieces of rubber between the mounting plate and coil before to dampen the chatter with some success.



Sent from my iPhone using Tapatalk
 
brantmacga said:
OP said "general purpose "..... I'm pretty sure these are DP contactors they're using for lights.

Some definite purpose contactors are just going to chatter like that.
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I agree.

Look at that, twice in a few minutes. Looks like I got to find my grumpy pills. ;)
 
I had this problem recently. I disassembled the contactor noticed metal dust got magnetized inside.
I had created metal dust in the enclosure from cutting custom K/O's in the box with a metal cutting hole saw and use of self tapping screws. Once I got all this out the buzzing stopped.
 
tortuga said:
I had this problem recently. I disassembled the contactor noticed metal dust got magnetized inside.
I had created metal dust in the enclosure from cutting custom K/O's in the box with a metal cutting hole saw and use of self tapping screws. Once I got all this out the buzzing stopped.
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Could be foreign material inside someplace. Even if they are definite purpose contactors, new Square D DP contactors are reasonably quiet initially, give them some time and they may not be though.

Could be a damaged shading coil also but don't seem as likely to have that on all three of them though.
 
patricknola said:
Hey Guys, I am working for a guy and we are wiring a small retail strip mall new install. We have lights running around the outside of the building and the contactors for the lights are mounted next to the panel outside. We have 3 new 120 volt square d general purpose contactors for the lights and everything is working fine except the contactors are humming really loud. if we press on the contactors they humm less. Otherwise they work fine. Any insight?
Click to expand...
Dirt/swarf between the pole faces maybe......
 
* Wrong voltage/frequency
* Dirt/rust on armature faces
* Broken/missing shading coils
* Cheap Chinesium contactors
* Installation amplifying sound

If everything looks okay about the contactors themselves and you're not interested in replacing them, then I would make a resilient mount out of flexible washers and call it a day. Try to avoid natural rubber that will deteriorate quickly.
 
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