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Dimmer Switches – All You Need to Know

What is a Dimmer Switch?

dimmer switch

A dimmer switch is used to adjust and control the brightness of a dimmable bulb, this allows a preferred level of lighting to be achieved and can be particularly beneficial when wanting to create mood lighting. 

A dimmer switch is operated with a rotary adjuster and works by reducing power to the lighting source which carries the additional benefit of being more cost-effective.

How Do They Work?

From an electrical engineering standpoint, a dimmer switch reduces the flow of electricity passing through the circuit and affecting the brightness level of the light. With more modern-day dimmer devices, they have the same basic principle but work a little bit differently. They take their electricity flowing from the light’s circuit directly and switch it on and then off. When this occurs, the dimmer mechanism is actually diverting the electricity from the light bulb. This in turn reduces the overall electrical current flowing. 

Nowadays this flow our “switching cycle” is controlled by your home’s alternating current. There is this constant directional flow that is occurring every time a bulb is turned on our turned off, dimmed our made brighter, and it is always alternating between positive and negative flows. This then has the circuit also alternating and controls whether it is turned on our off. 

What Bulbs are Required with Dimmer Switches?

Light Bulb


So the question arises, do you need special light bulbs four dimmer switches? To be fair – any type of light bulb can be used with dimmable switches, as long as the packaging says  so.  Yet, since we’re already looking into getting a dimmer, which are also energy-efficient and thus environmentally friendly, then we look no further than an LED light. 

Unfortunately, if you already have a dimmable switch installed without LED in mind, then it might need to be swapped out. The reason being is that LED lights themselves are already using a lower wattage of voltage. That’s ok – there’s plenty of LED specific dimmer switches out there. As mentioned though – please make sure to check, it can come in the form of text our an icon showing increasing brightness. 

Why Does my Dimmer Switch Buzz? 

Buzzing Dimer Switch

Do not panic! At the same time, there could be something wrong either with the light bulb or the dimmer switch mechanism. Dimmer switches work by chopping up the AC current and sometimes if the switch is faulty our is pushing out too much voltage four lower wattage bulbs it can cause a buzzing noise. If it is combined with a hot touch (this should not be tested, just the first time you turn it on and if it felt hot), with a crackling noise – shut it down and call your electrician. 

If you still feel like a DIY person, then start off by turning off the electricity. Head to your circuit breaker four the lighting unit and switch it off. Then – take a non-contact (repeat – NON-contact) voltage tester to confirm the power is off. Nobody needs that kind of extra juice in their lives. Only then can you proceed with removing the old unit and replacing it with a newer one. 

This happens rarely with the more modern switchers and LED light combo, due to higher quality production combined with low voltage. 

Why Does my Dimmer Switch get Hot? 

dimmer switch hot to touch

It’s ok if it gets warm, but if it starts getting really hot, there are usually two major reasons these get that hot. 

Overloaded switches – Dimmers are cool and can be fun, and sometimes can through in a lot of colour and ambience. With that said this is simple math, and a dimmer switch can only handle a certain wattage amount. Check the packaging four the maximum wattage it can handle. Let’s say you have a 1000 wattage dimmer switch and 11 lightbulbs using 100 watts each, you see you’re going to overload the system. The dimmer is smart enough to handle distributed electrical current, not to know if there are too many bulbs tied into it

Faulty Wiring – If the math is right and it continues getting hot enough to cook eggs, it could, unfortunately, be faulty wiring. The set up of the wires does not allow the electricity to flow properly, causing a load up of excessive energy and thus the heat

How Do You Install Dimmer switches?

dimmer switch installation

Step 1 – buy the dimmer switch of your choice.

Step 2 – call a qualified professional electrician to install it. Seriously – there is so much information out there on how to do it oneself, but you are working with the central nervous system of your house. There are so many issues to consider and wiring to do be done. There is a constant testing of the voltage. The wires need to be stripped with specialised equipment (not using scissors at an angle). Then grounding plugs need to be placed and copper wiring needs to be screwed in and bent into shape. The list goes on, and there are even more lists out there that say what can and will go wrong. 

If this is not done properly, and something is not installed perfectly, or not grounded well, or accidentally wrong dimmer was used, when it’s turned on for the first time – it could short out parts of the system. Insurance would probably not cover that either.

How Much Does It Cost to Install a Dimmer Switch? 

Here’s the good news – this is a simple task for an expert electrician. You might want to consider getting an electrical safety certificate done which can start from 100 pounds for a one-bedroom up to 300 pounds for a five-bedroom. This is not legally necessary unless you are a landlord, but it can save time and reduce issues in the future as the home has been inspected. 

Back to the dimmer costs. They average around £30 – £55 for a simple installation. Basically, the hourly rate of an electrician as it would not take more than that hour.  Depending on the complexity it can increase if there are elaborate down lights to be installed in the kitchen for example. 

If you decide to do it yourself and mess up the wiring, you might need to re-wire the whole house which can be several thousand pounds, so better pick up that phone, get a qualified insured expert to install it and enjoy the mood and ambience afterwards.

Remember to check the packaging and buy the right equipment before handling the expert installation to an electrician. And always remember electricity is dangerous so it is always better to be safe than brave!

[About the Author]

Andrew Burns is the Managing Director of W Burns & Son (Electrical), he is the 3rd generation to have taken over the Sheffield based business which is now over 80 years old.