People like to have a choice, and sometimes ‘on’ and ‘off’ aren’t enough. Dimmers allow you to adjust the brightness of your lights. Being able to do so can be handy for creating a mood, adding a bit of extra illumination (for safety or work), for saving energy and money on your power bills, or perhaps to manage your home's visual aesthetic.
Dimmers are the most basic form of lighting control, and can be installed with most lights. Unlike most other electric light controls, installing a dimmer switch won't cost you thousands of dollars and require specially installed computerised gear.
How dimmers work
In simple terms, modern dimmers work by changing the amount of voltage in the lighting circuit, which in turn affects the amount of power the light uses, which affects the brightness of the light. Most common dimmers are controlled either with a turnable knob, or with a slider that moves up and down.
There are some benefits to be had in terms of energy efficiency by installing dimmers too. If you dim the lights by at least 25%, you will save approximately 20% of the electricity required. Dim the lights further, and you will save more. It also means your lamps will last longer, depending on the types of lamps you use - you may get 3 or 4 years out of a lamp that would otherwise last 5 or 6 months.
Halogen bulbs and dimmers
There are complications to consider with halogen globes, though. Halogen globes are typically optimised to work best at a specific heat and voltage. Dimming them with a basic dimmer may cause them to operate outside of this optimal range and affect the halogen cycle, considerably reduce their lifespan.
This isn't necessarily the case, though. A better quality dimmer will reduce the average voltage to the globe by clipping part of the AC waveform, rather than proportionally manipulating the voltage. If in doubt, check with your hardware store or electrician to ensure that you get the right type.
Dimmer cost and efficiency
Dimmer switches themselves are very efficient devices. In the past, dimmers were made using rheostats (also known as potentiometers), which were less efficient than the silicon controlled rectifier (SCR) thyristor versions used today.
Using a dimmer light switch is perhaps the cheapest and most versatile way to control the way you use your lights.