What does dimmer switch buzzing mean?

Susan Fernandez January 01 2022

Dimmer switches are quite safe when they are used normally. They are designed to make it possible for you to change the amount of light in a room, usually by adjusting the voltage sent through the circuit.

Sometimes when you turn on your lights at night or enter a dark room, you hear a buzzing sound coming from your dimmer switch. This is not necessarily dangerous but can be annoying and disruptive. The noise may go away after some time but if it doesn't, there are ways for you to get rid of it.

What if something went wrong?

You need to pay attention to your dimmer switch if it:

  • buzzes loudly
  • emits a burning smell
  • has sparks coming out of it

These signs indicate that there is something wrong with your dimmer switch. You should turn off the circuit to prevent any further damage, and call an electrician to fix your dimmer switches right away.

Most electrical fires are caused by faulty wiring or dimmers switches. If you suspect that something is amiss with your dimmer switch, you do not want to take any chances because of its potential for danger. 

What causes my lights to buzz/hum?

There are several reasons why your lights might be buzzing or humming when they shouldn't be. Some of these problems include:

  1. A loose wire connection in your dimmer switch. Most of the time, turning off the circuit will fix this problem. If it does not, you need to call a professional electrician.
  2. You might be using a power source that is too low for the number of lights on the circuit. Dimmers switches are designed to work with specific voltage ranges from 120V to 277V. Using anything lower than 120V or higher than 277V may cause buzzing sounds.
  3. Your wattage load is too high for your dimmer switch and/or power supply. Check your wattage rating of either device and make sure it matches the load requirements of all appliances connected to them combined. Too many appliances can burn out a dimmer switch, regardless of wattage.
  4. The dimmer switch is wired incorrectly. When you install a dimmer switch, it has to be connected with the correct polarity (meaning that the line and load wires have to be correctly switched). A professional electrician can help you fix that problem.

What if my lights keep buzzing?

If your lights continue to buzz even when they are turned off, you need to check it out.

Your light bulbs might be at their end of lifespan and need replacement. If they pass their suggested lifespan or burn out immediately, replace them with high-quality bulbs such as Philips LED light bulbs. They also last longer than traditional ones so you will not experience the same problems again in the near future. Call an electrician if you cannot figure out why your lights are buzzing or humming. They can help you fix the problem and make sure that it doesn't happen again.

Your dimmer switch may be faulty. In this case, turn off the circuit and have a professional electrician check your dimmer switches to ensure that they are working properly. If there is something wrong with them, it is best for you to simply replace them completely because of their potential danger when used improperly or not kept in good condition.

Your home might not have a GFCI protection system. If you notice that your lights keep buzzing even while they are turned off, this could be the reason. The only solution for this is to call a qualified electrician to install a whole house GFCI protection system in your home.

Is it normal when the dimmer switch buzzes?

Most dimmer switches are designed to make a slight buzzing sound, but the noise should not be loud or high-pitched. If you hear popping sounds, hissing noise,s or faint zapping sounds, there might be problems with your dimmer switch.

Only when you feel the dimmer switch hot to touch can not be considered normal. Also when you smell the burning odor, it is wise to call an electrician immediately because this means there might be problems with your dimmer switch that can potentially cause a fire.

To ensure that your dimmer switch is working properly, you should check for the following:

  • Slight buzzing noise when using the switch or lights connected to it.
  • A slight drop in voltage when activating the switch. If you notice a sharp decrease of more than 5% in voltage, it could indicate problems with your dimmer switch.
  • Functionality - make sure that all settings are functioning as intended. Additionally, checking if proper operation occurs at multiple loads on the single circuit is also important since not all switches can handle various lighting loads simultaneously without overheating or shorting out. Dimming performance is tested by varying degrees of load being applied to the circuit monitoring power draw levels and any increase in temperature of both switch and wiring.
  • Proper installation - make sure that the dimmer is wired correctly. If you notice any "dead spots" or areas where it is almost impossible to turn on or off, then there might be faulty wiring that needs replacement.

See the difference: mechanical buzz or electrical noise?

Be sure, that while talking about buzzing noise you do not confuse it with the other "buzzing" you might hear. There are several possibilities:

Mechanical buzz - this one is typical for, let's say, a hairdryer that has something wrong inside (e.g.: bad bearing or needed replacement of part) or even a computer power supply fan that might have deteriorated bearings or just stuck/blocked rotor that prevents motor impeller from turning properly.

Usually, you can replace this type of buzzing with some "white noise" just by squeezing the motor housing a little bit to free up stuck parts. The only problem here is usually mounting screws which can be rarely inaccessible without taking off the entire cover which may require proprietary tools and special knowledge about a particular device.

NOTE: Some newer fans come with bearing retaining clips that keep them in place (like on PSU fan or CPU fan).

Electrical buzz - this is an electrical signal created by some component usually for a short period of time when changing the state of the circuit it belongs to. It is usually caused by a power supply oscillator, but can also come from other parts like capacitors when they lose contact with the board and try to "recharge" via coil wire which acts as a generator. This is usually a momentary zapping sound and it goes away as soon as the coil wire gets disconnected from the capacitor. It might also come from the faulty switch itself.

Mechanical click - this one is pretty rare because usually, microswitches do not have any mechanical parts inside which could cause such noise (maybe except the plunger that presses the button).

On very few models (usually cheaper ones like the Sanwa OG series) you may find some ball bearing that serves as part of the plunger, but it should NOT make any clicking sounds! It can crack or break, but then you will feel vibration during pressing the button or using it and it won't be clicky. If your arcade stick makes a loud "click" each time you press the button, there must be something wrong with it.

Electrical click - Some microcontrollers (mostly ones with an internal oscillator) produce momentary negative voltage when powering up which may trigger surrounding electronics components to hold logic "0" state for a moment or immediately start functioning.

This is usually caused by the faulty microcontroller, but can also come from other parts like capacitors when they lose contact with the board and try to "recharge" via coil wire which acts as a generator. This is usually a momentary zapping sound and it goes away as soon as the coil wire gets disconnected from the capacitor.

NOTE: Usually you will need some good ears to hear this kind of noise because most of the time it's beyond the audible range (>20kHz). If your arcade stick makes a loud "click" each time you press the button, there must be something wrong with it.

Mechanical rattle - this one is also pretty rare and usually means that your arcade stick needs repair or replacement of parts or even the entire case. The only known example of such noise is an unreliable microswitch design from Seimitsu. If your arcade stick makes a loud rattling noise when you shake it, there must be a problem with the internal components which will require opening up. Otherwise, try to show it to a service center for repairing/replacing parts.

Instruction on what should you do if the dimmer switch buzzes and the light is flickering

If you switched the light in your room and it started flickering, then the problem lies in your dimmer switch. Find the diagram that matches yours and see if you can fix it yourself or not. If you cannot, contact an electrician to do the repairs for you.

For fixing it yourself you will need to know exactly what is wrong with your dimmer switch. Usually, the problem is in the contacts, so you will have to clean them up and sand down all rough edges on both switch-wire connections until they are perfectly flat. After this sanding treatment, make sure that there are no metal particles left by using some sandpaper or fine steel wool.

Other problems could be caused by the wear of cheap dimmer switches that were made with plastic parts instead of metal ones that would last longer. In this case, you will have to buy a new one, but it will most likely cost more than the regular 100$ for an electrician coming over to do repairs for you.

Sometimes clicking noise can be caused by a faulty power supply oscillator that has rubbed contacts or a bad capacitor. You can test it by using a multimeter set to measure voltage and touching the probes to points on the circuit board where metallic parts of the switch used to be connected to the power supply. If you are getting anything over 5V, then that is most likely the case.

If you are unable to fix your dimmer switch yourself, try asking an electrician if it is worth repairing it for money. Maybe he will tell you that your dimmer is old and there are no replacement parts for it, so spend 10$ more and buy a new one which also gives an energy-saving advantage.

If you have a dimmer switch with metal contacts inside - throw away this one immediately because usually problems associated with them cannot be fixed easily and they are very short-lived. If you have a dimmer switch with plastic parts and clicking noise comes from there, then repair should be possible and cost of repair will be little more than the average price for a new model.

So, your answer to the question of what does dimmer switch buzzing mean can be easily deduced from the electrician's advice about repairing it or not.

Tips on how to choose a good dimmer switch

  • Dimmers that are used for LED bulbs normally don't buzz at all.
  • If you still have buzzing noise then it can be caused by metal contacts inside your dimmer, so it is better to get rid of this one and buy a new - more energy-efficient one.
  • Noise can also come from capacitors when they lose contact or try to "recharge" via coil wire which acts as a generator. This type of sound is usually a momentary zapping sound and goes away as soon as the coil wire gets disconnected from the capacitor.

NOTE: Usually you will need a good ear for hearing this kind of noise because most of the time it's beyond audible range (20kHz+). If you hear a click each time you press the button on your arcade stick, then it's most likely to be caused by a faulty capacitor or bad coil wire inside.

Wires get loose over time, so they need resoldering at least once every few months (if you play your stick regularly). Good solder connection is a fundamental part of a good arcade stick build that will last.

Bottom line

If your dimmer switch is buzzing and turns on and off lights very quickly then it means that contacts are dirty or not making good contact with each other. This can be easily fixed by sanding both metal contacts so they have a nice and even surface without any sharp edges. If you cannot do this yourself, ask an electrician to take a look at it and possibly repair it for you for about 100$.

If your dimmer switch makes a clicking noise, then one of the capacitors inside went bad which should be easily fixable if you know how to solder stuff. If not, just buy a new switch because repairing those will cost significantly less than buying replacement parts.