Enter the promo code "evolve15" at checkout to receive a 15% discount on BG Evolve. (Minimum purchase of £50.00 required)

Understanding the Basics of Dimmers

Understanding the Basics of Dimmers
Understanding the Basics of Dimmers

Lamp Dimmer settings are essential for achieving the ideal atmosphere when it comes to house lighting. These gadgets give homeowners freedom, energy savings, and a sophisticated touch by enabling them to change the brightness of their lights. Any house would benefit greatly from the installation of dimmers, which provide the ideal balance of improved ambience, reduced energy use, and more control over lighting. Whether you choose a cutting-edge smart dimmer or a conventional rotary dimmer, knowing how these devices operate will help you make the best choice and realize the full range of advantages.

Essentially, a dimmer is an apparatus that regulates the intensity of light. By modifying the electrical power supplied to the lightbulb, this is accomplished. Conventional dimmers function by adjusting the voltage waveform provided to the bulb, which lowers the average power delivered. More advanced electrical components are frequently used by modern dimmers to accomplish the same result. But how precisely do dimmers operate? This extensive blog post will examine dimmers' internal mechanisms, many varieties, advantages, and installation and usage practices in UK homes.

The Principle of Dimming 

Gaining an understanding of the operation of light bulbs is crucial to comprehending dimmers. To create light, incandescent bulbs, for instance, heat a filament until it glows. The filament's temperature is influenced by the amount of electrical current passing through it, and this temperature determines the light's brightness. A lamp dimmer reduces light output by lowering the filament's temperature through a reduction in current. 

LED lights, on the other hand, work on a different concept. By recombining electrons with electron holes inside the device, they produce light through electroluminescence, which releases energy in the form of photons. Dimming LEDs entails either altering the pulse width modulation (PWM) signal or regulating the current that is delivered to the LED chips.

How Dimmers Work: A Technical Perspective

It is crucial to comprehend the underlying technology in order to get deeper into the operation of dimmers. Three main techniques are employed in dimmers: digital control, PWM, and phase-cutting.

Phase-Cutting Dimmers

The most popular kind of dimmers used in homes are phase-cutting models. They function by cutting the AC waveform, which essentially lowers the amount of power supplied to the lightbulb. Two primary categories of phase-cutting dimmers exist:

  • Leading-Edge Dimmers: By severing the waveform's leading edge, these dimmers partially switch on the electricity during an AC cycle. Usually, incandescent and halogen lamps are used with them.
  • Trailing-Edge Dimmers: These dimmers interrupt the power supply halfway through the AC cycle by cutting the trailing edge of the waveform. Because of their quieter operation and smoother functioning, they are more appropriate for use with LEDs and compact fluorescent lights (CFLs).

Pulse Width Modulation (PWM)

PWM dimmers operate by quickly turning on and off a high-frequency light source. The apparent brightness depends on how long the "on" period is compared to the "off" time. This technique is very useful for dimming LEDs since it preserves the colour temperature and brightness of the lightbulbs.

Digital Control

Digital control methods, in which microprocessors oversee the dimming process, are frequently employed by smart dimmers. These dimmers offer fine-grained control over light settings and are capable of communicating with other smart devices. To get the best results with various kinds of bulbs, digital dimmers can combine phase-cutting and PWM.

Types of Lamp Dimmers

There are several types of lamp dimmers, each working slightly differently. The most common types include:

  1. Resistive Dimmers
  2. Rheostats
  3. Phase-Cut Dimmers
  4. Pulse Width Modulation (PWM) Dimmers
  1. Resistive Dimmers

Among the most basic kinds of dimmers are resistive dimmers. In order to lower the voltage and current sent to the light, they employ a variable resistor. The lamp dimmer dims the light by decreasing the power flow and raising the resistance. These are typically used with halogen and incandescent light bulbs. 

How Operates: 

  • A slider or rotary knob is used to change the resistance.
  • Diminished current goes to the light with increasing resistance.
  • A reduction in power causes the lamp to dim.
  1. Rheostats

Certain older dimmers make use of rheostats, a kind of variable resistor. Although they produce a lot of heat and are frequently bigger and less effective than resistive dimmers, they function similarly. Although they were ubiquitous in the early dimming systems, they are not utilized as much anymore. 


How It Operates: 

  • The resistance in the circuit is adjusted by a dial or slider. 
  • A higher resistance causes the light to fade and the current to drop. 
  • Because of the energy wasted as heat, this approach may not be very efficient.
  1. Phase-Cut Dimmers

Currently, phase-cut dimmers are the most commonly utilized kind of lamp dimmer, particularly for contemporary lighting systems. They function by interrupting a section of the AC voltage waveform, thereby lowering the overall power delivered to the bulb.

There are two main types:

  • Leading-Edge Dimmers: Also known as TRIAC dimmers, they cut the leading edge of the AC waveform. They are suitable for resistive loads, like incandescent and halogen bulbs.
  • Trailing-Edge Dimmers: Also known as reverse phase dimmers, they cut the trailing edge of the AC waveform. They are better suited for capacitive loads such as LEDs and some compact fluorescent lamps (CFLs).

How Operates: 

  • During each AC cycle, the dimmer rapidly turns on and off.
  • The dimmer modifies the amount of power supplied by adjusting the waveform's cutting point.
  • While trailing-edge dimmers switch off halfway through the AC cycle and turn on at zero crossing, leading-edge dimmers turn on halfway through.
  1. Pulse Width Modulation (PWM) Dimmers

LEDs are often dimmed using PWM dimmers. They function by using a high frequency to turn the light on and off. By varying the ratio of the "on" time to the "off" period inside each cycle, the perceived brightness may be adjusted.

How Operates: 

  • The LED is quickly turned on and off by the dimmer via a high-frequency switch.
  • One may change the average power delivered to the LED by adjusting the length of the "on" pulses.
  • By using this technique, you may lower LEDs without sacrificing their colour temperature or efficiency.

Setting Up and Utilizing Dimmers in UK Houses 

Although installing a lamp dimmer switch might be simple, it's crucial to abide by safety precautions and take your lighting fixtures' compatibility into account.

Considering Compatibility 
Make sure the dimmer works with the lights you currently have before installing it. Not every kind of bulb can be dimmed by every dimmer. Here is a brief how-to: 

  • Halogen and incandescent lightbulbs: These types of bulbs work with the majority of dimmers, even the most advanced ones. 
  • LED Bulbs: Usually smart or trailing-edge dimmers, these dimmers are made especially for LEDs. 
  • Not every CFL bulb can be dimmed. Use an appropriate dimmer and make sure your CFLs are dimmable.

Safety Precaution

Safety is of the utmost importance when dealing with electrical infrastructure. It is advisable to engage with a licensed electrician if you are unclear about the procedure. Observe these common safety guidelines:

  • Always turn off the electricity at the circuit breaker before using any electrical equipment.
  • Observe the manufacturer's instructions: The dimmer manufacturer's installation instructions should be read and followed.
  • Employ the Right Tools: To prevent harming the dimmer or wiring, make sure you have the appropriate equipment for the task.


In the UK, where energy costs are a concern and creating a cozy home environment is a priority, dimmers provide an elegant solution. By carefully selecting and installing the right dimmers, you can transform your living spaces and enjoy the many advantages they offer. So, why not consider adding dimmers to your home from The Electrical Outlet and experience the difference they can make? The Electrical Outlet provides a large selection of lamp dimmer alternatives from their extensive variety of available options. There are one to four gang dimmers available in each of the dimmer ranges. All of them work with LEDs, but they may also be used with halogen or incandescent lights.



What is a Dimmer?

A dimmer is a device that adjusts the brightness of a light by controlling the amount of electrical power delivered to the bulb.

How Does a Lamp Dimmer Work?

A lamp dimmer works by altering the electrical power supplied to the light bulb. The most common methods include:

  • Resistive Dimming
  • Phase-Cutting
  • Leading-Edge Dimmers
  • Trailing-Edge Dimmers
  • Pulse Width Modulation (PWM)

These methods adjust the light output, allowing for varying levels of brightness.

Related News