# Lighting Contactors that "buzz"



## DEA AGENT (May 21, 2008)

I have encountered this same problem in the past. Replaced with new one, no worries.

I have gone through 3 lighting contactors, all with this problem. When they are energized via time clock, the lights come on and all is good, except for this god awful "buzzing" noise. The magnets are vibrating violently, and causing this noise that will drive you bonkers. The lights work fine, everything seems good, except something is "loose". I inspected it and everything looks fine....although I don't have a whole lot of experience with troubleshooting contactors. Usually it either works or it doesn't.

So I finally got one that was fine, and now another contactor, same model, in the same can, suddenly started buzzing today.  

Am I overlooking a simple fix? Anyone else encountering these loud buzzing contactors?


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## TOOL_5150 (Aug 27, 2007)

Thats what they do. You can try mounting them on a backplate or use rubber as an insulator. In this case, I would get a piece of thick rubber, and mount the contactor to its enclosure with the rubber inbetween.

You can always just move the contactor if its bugging you that much.

~Matt


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## Greg (Aug 1, 2007)

Another option is to use mechanically held contactor for lighting instead of electrically held contactors. They do not make any noise but they wil require a re-wire to bring a latch and unlatch signal. It is real easy not as complex as it sounds.


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## frenchelectrican (Mar 15, 2007)

The other option I used from time to time is use the transfomer to downstep to 24 volts and run it thru the receficer { it will change from AC to DC } that useally take care of the noise most case.

Make sure you get 24 DC coil but I don't know if your contractor do have other voltage rating that can take DC current that something you may want to think about it.

Otherwise put a rubber pad that useally cure the noise but watch the grounding and bonding as reqired.

Merci,Marc


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## DEA AGENT (May 21, 2008)

This sound is not the normal, quiet buzz. This is a deafening buzz. You can't have a conversation in the electrical room. It is abnormal.

Oh and I used the rubber pad idea the last time I had this problem. It didn't fix it. I had to get a new one.


Yeah, sounds easy enough.....I am trying to find an easy fix because, well, after I complete this job, I am moving to another company. The is the last item I need to take care of so I can move to another company.

I am only going to fix it tomorrow or go pick up a new one.


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## DEA AGENT (May 21, 2008)

A thought occured to me....maybe I need to open it up and flip one of the magnets.....but I think they only go in one way. Maybe reverse polarity is making it freak out....but I would think if that was the problem, it then wouldn't be able to close at all.


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## frenchelectrican (Mar 15, 2007)

Superloud buzz is not correct did you check the contractor armture make sure they are moving smooth and it make full travel ?

And the other thing is the armture is not cocked when it close the contractor it should be fully close with no gap on the lamiate coil { armture }.

This what I useally do turn off the power for a min and _manually_ push on the armture to make sure they are sliding smooth nothing can get caught on and look for any gap on the armture it should be zero or very little without clattering.

When you turn on it should able slam right there and not showing any gap unless you used the DC coil on AC system which a good buzzing noise there.

Merci,Marc


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## TheRick (Apr 13, 2008)

DEA AGENT said:


> A thought occured to me....maybe I need to open it up and flip one of the magnets.....but I think they only go in one way. Maybe reverse polarity is making it freak out....but I would think if that was the problem, it then wouldn't be able to close at all.


 
The cause of your "deafening buzzing" could be due to a damaged or missing shading coil. Have you checked that the shading coil is in fact installed, and if so is it in one piece. I have had brand new contactors right out of the box come both without the shading coil, or with a damaged one.


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## brian john (Mar 11, 2007)

Ricks has it if the noise is above what is expected. Generally lighting contactors are mechanically held as even the quite hum in an office environment can be distracting.


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## DEA AGENT (May 21, 2008)

yes all the springs seem to be working smoothly.

One of the replacements I got I had to engage by hand....only for it to pop back out on its own. It also had the deafening buzz. The springs on that one were definately worn. It also had white out on it covering up where it said "120v" and with a ball point pen "277v" was written over it. Ghetto ass supply house.....and yes a 277v contactor is what I need.

Anyway today I took it apart again, all the springs seemed fine, I blew it out with compressed air, and reinstalled it.

The buzz was quiet almost normal, but not quite. Not quiet enough for me to call for final inspection. So I turned off the time clock. When I threw the time clock back on energizing the contactor, it was louder than ever!!  

Anyway, I just ordered a new one today. It better work properly!

I should have talked the owner into a lighting control panel.


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## randomkiller (Sep 28, 2007)

DEA AGENT said:


> yes all the springs seem to be working smoothly.
> 
> One of the replacements I got I had to engage by hand....only for it to pop back out on its own. It also had the deafening buzz. The springs on that one were definately worn. It also had white out on it covering up where it said "120v" and with a ball point pen "277v" was written over it. Ghetto ass supply house.....and yes a 277v contactor is what I need.
> 
> ...


 
Have you taken a voltage reading at the coil with an actual meter? Maybe the time clock contacts have some resistance through them.


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## Mountain Electrician (Jan 22, 2007)

TheRick said:


> The cause of your "deafening buzzing" could be due to a damaged or missing shading coil. Have you checked that the shading coil is in fact installed, and if so is it in one piece. I have had brand new contactors right out of the box come both without the shading coil, or with a damaged one.



Yep, seen it myself. Also, I've seen rust build up causing the same chattering.
Although I can't imagine 3 contactors would have the same problem.

I think checking the voltage at the coil is a good idea.


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## DEA AGENT (May 21, 2008)

No, but one time clock is controlling two contactors. One is good (now after replacing with a different model), one has repeatedly had the same problem.

For now, I am going with a mechanical error somewhere that I am not seeing. These crappy contactors have been a problem for me in the past.

The one I got that finally worked was a Siemens General Purpose Contactor. I told the supply house to hook me up with another one of those to replace the other POS. There is one more of the crappy lighting and heating contactors in the can, but it seems to be working properly (it is energized by a different timeclock) so I will just leave it.

The rediculous series of contactors and timeclocks in this building drives me up the wall. Get with the times, man!!! :jester:


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## randomkiller (Sep 28, 2007)

DEA AGENT said:


> No, but one time clock is controlling two contactors. One is good (now after replacing with a different model), one has repeatedly had the same problem.
> 
> For now, I am going with a mechanical error somewhere that I am not seeing. These crappy contactors have been a problem for me in the past.
> 
> ...


 
Well, even if it was controlled by a PC program it would still fall back to a contactor to turn things on and off.


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## DEA AGENT (May 21, 2008)

true, but it is nice to have it all in one neat little package.


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## scrooge (Jan 26, 2008)

*LW*



DEA AGENT said:


> No, but one time clock is controlling two contactors. One is good (now after replacing with a different model), one has repeatedly had the same problem.
> 
> For now, I am going with a mechanical error somewhere that I am not seeing. These crappy contactors have been a problem for me in the past.
> 
> ...


What kind of load is on each contactor?


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## randomkiller (Sep 28, 2007)

scrooge said:


> What kind of load is on each contactor?


There isn't a big chance of the load on the contactor having any issue with the contactor pulling in.


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## John Valdes (May 17, 2007)

Cheap contactors have cheap coils in them. And if the voltage is lower than 10% of nameplate, the coil will not hold the iron in. While it is buzzing, push the iron in with your screwdriver and see if it stops. If it stops buzzing you have a mechanical issue, alignment, shading coil or dirty irons. 
Take apart contactor and clean all mating surfaces with an abrasive pad. Note: It is not worth the labor to disassemble most IEC contactors. Check that the iron slides easily in and out.
Using ohms law, verify the ohm reading across the coil, then check voltage with the coil energized.
If you have found a different brand that does not chatter, why not change to those.
I found some real inexpensive ones at www.wegelectric.com. I have never had an issue with them, and they are 1/3 the price of the major brands. Oh, and these can be rebuilt just like NEMA.


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## pat c (Aug 18, 2008)

ive encounterd that problem before i use to cheap out with contactors and waste time trying to get ride of the noise. but these are tricks to avoid the noise.. first thing make sure there lighting contactors not heating because with lighting especially if there hps or mh lights.. second most ppl dont notice this but when they mount the contactor box mke sure to pre drill all ur knock-outs before intalling the cantctors , try not to make any metal get inside the coil that causes the buzz. if so use compressed air to remove everything.. double plate ur box to avoid vibrations...


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## scrooge (Jan 26, 2008)

*Agreed small chance.*



randomkiller said:


> There isn't a big chance of the load on the contactor having any issue with the contactor pulling in.


Is there a way to swap loads on contactors?


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## John Valdes (May 17, 2007)

Yes, move one set of wires from one contactor to another.


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