Dimmers causing a hum

Merry Christmas
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quogueelectric

Senior Member
Location
new york
I occasionally have customers asking me why thier dimmers make noise and what they can do about it. I dont really have a good answer for them does anyone else have an explanation and or solution??
 

mdshunk

Senior Member
Location
Right here.
That's a tough one. The cheaper the dimmer, the higher the likelihood that the dimmer or the connected lamps will hum. Changing the dimmer sometimes helps, and that's my first suspect if there's a no-name dimmer installed. I've had better luck changing out the lamps to eliminate dimmer hum. The most recent one was several recessed fixtures with R-30's that the dimmer was really humming. Changed out the R-30's with halogen PAR-30's, and the problem went away. I hate to say it, but the solution is often a trial and error situation.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I agree with marc. I have had more problems with the bulbs than the dimmer. Check and make sure it is the dimmer humming and not the bulb.
Try a different brand or a high voltage bulb-- it may help.

Now if we can get those bulbs to hum it to a holiday tune it may not be so bad.:smile:
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Since Allenwayne has apparently fallen off the face of the earth, I shall stand in his stead and repeat his customary joke for this topic:

allenwayne said:
It hums because it doesn't know the words!

mdshunk said:
I hate to say it, but the solution is often a trial and error situation.
Finally found something the megger can't do, ey? ;) :D
 

mdshunk

Senior Member
Location
Right here.
georgestolz said:
Finally found something the megger can't do, ey? ;) :D
No, a megger might actually solve the issue. Leave the dimmer connected, and megger it. The megger will blow it up, and you'll have to replace the dimmer. That might solve the issue. :D
 

480sparky

Senior Member
Location
Iowegia
This is caused by the lamp filament vibrating as the dimmer rapidly switches the lamp on and off. Lamp hum is generally noisiest at the mid-range [50%] dimming level. If this happens use rough service lamps [sometimes called garage door opener or appliance bulbs], physically smaller lamps, or lower wattage lamps.

Sine2.jpg
 
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76nemo

Senior Member
Location
Ogdensburg, NY
mdshunk said:
No, a megger might actually solve the issue. Leave the dimmer connected, and megger it. The megger will blow it up, and you'll have to replace the dimmer. That might solve the issue. :D


Got a good laugh out of that one. When you get stumped, through it some real juice:grin: BAD dimmer, take that:wink:
 

mdshunk

Senior Member
Location
Right here.
From Lutron's stie:

What can I do to minimize lamp hum?
Occasionally, lamps may generate noise when dimmed. This noise is caused
by vibration of the lamp filament as the dimmer rapidly switches the lamp on.
Lamp buzz, if it occurs, is generally noisiest at the mid-range (50%) dimming level.
Lutron suggests the following solutions:
• Select another brand of lamp or use lower wattage lamps (100W or less)
• Use rough service lamps
• Use a physically smaller lamp
• Install a lamp debuzzing coil in the lighting circuit, see pg.189

Technical document .PDF on Lurton's "lamp debuzzing coil" gizmo:

Lutron Application Note #13
 
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ItsHot

Senior Member
we don't make them!

we don't make them!

This reminds me years ago, I had done a small residential job. Lighting upgrade..can lights etc., and one ceiling fan. The fan brand at the time was one that everyone thought was the greatest! After trying what seemed forever to balance the thing and the customer blaming me, I told him"we don't manufacture the things ,we just install them"! I saw the guy later on and he said that he had to buy a different fan!
 

quogueelectric

Senior Member
Location
new york
I truly apreciate the response

I truly apreciate the response

These solutions suggested by lutron are hard to implement. I have never seen a rough service lamp other than an a19 100watt. Most recessed lighting has a max of 60-70 watts in a residential condition. I have heard that there are 3 basic dimmers electroniclly and you are supposed to match the load to the dimmer yet I still have customers asking me why this happens and now I will at least have an answer for them. Thanks again.
 

GilbeSpark

Senior Member
Location
NC
I've always wondered about those Lutron lamp debuzzing coils. Anybody ever tried one? My lights in my kitchen buzz but I didn't want to spend the $150 or so lutron wants for one of those things. I think I'll go with the halogens.
 

brian john

Senior Member
Location
Leesburg, VA
? Select another brand of lamp or use lower wattage lamps (100W or less)
? Use rough service lamps
? Use a physically smaller lamp
? Install a lamp debuzzing coil in the lighting circuit, see pg.189 *1

*1 From page 189 - If you feel the necessity to contact us we'd prefer you buy our competitors product
 

e57

Senior Member
Many manufacturers make the lamps differently if you need to destroy a few or peek inside the filament is supported on tiny wire hooks. The shorter the filement, and more it is supported the less the lamp will hum/buzz.

De-buzzing coils do reduce it a lot - but you are only going to move the hum to it's location often, and spend a bit of money...

But better design in the way of remote transformers for LV lighting. And physically remote locations of the dimmers themselves helps a lot.
 

Tiger Electrical

Senior Member
That was a great link on Lutron's Application Note #13 Marc. It says the debuzzing coil hums, and the distance between the coil and the dimmer should be kept short (as in with the dimmer). I take that to mean the coil will hum instead of the dimmer buzzing???

Dave
 
FWIW, most, if not all, theatrical dimmers include a choke ("debuzzing coil") as an intregral part of the dimmer. The choke slows the rise of the wave (longer risetime) when the scr/triacc switiches on, and this cuts both the buzz and the RF noise generated.
 

dbuckley

Senior Member
Yep, Zbang has it right - installation of a choke does not "move" the buzz like some sort of star trek transporter, it reduces the buzz made by the dimmer and lamp by reducing the rate of change of current. Sure the choke buzzes, but thats not quite the point.
 
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