As an electrician installing LED lights has become the norm for me now, in fact, I don’t think I can remember the last time I installed a non LED light. Even though I install them all the time I wanted to do some research to find out if LED lights are AC or DC as I presumed they are always DC but am I wrong in this assumption?
In this article, we’ll briefly look at whether your new lighting fixtures operate under direct current (DC) or alternating current (AC) power supply, we will also investigate the difference between AC and DC LED lights and how they work!
The vast majority of LED lights are DC but powered from an AC supply. The AC supply found in homes or businesses is converted into a DC current by the LED driver. The driver sits between the supply current and the light-emitting diodes which produce the light.
Are LED Lights AC or DC?
First off, traditional incandescent, halogen, and fluorescent lights are AC. This is because AC voltage changes direction, which allows for a simpler transformer (coil of wire) to step voltage up or down.
LEDs, however, are DC. They only work in one direction, so they need a different way to work with AC power. Most LED lighting uses an electronic driver to convert power from AC to DC. And most LED drivers work like a switch-mode power supply, but instead of generating an AC output directly, they use a transformer or inductor to step down the voltage and rectify the output.
Difference Between AC and DC Light Bulb
Alternating current (AC) and direct current (DC) describe the two primary types of electrical circuits. The difference between the two is that in AC, the current flow keeps changing direction, whereas, in DC, the current only flows in one direction. This difference becomes important when selecting a type of light bulb to use with a particular circuit.
The electrical power used in homes and businesses is AC power because this type allows electricity to be sent over long distances. However, some circuits within the homes and businesses use DC power because it can be more efficient than AC.
Although the vast majority of LEDs in use in our homes are designed to work with AC currents we can purchase some that need a DC current supply. An AC LED uses an integrated circuit to convert the alternating current into a constant directional current to work as a regular diode. But, DC LEDs don’t require this conversion and can be used directly in electronic circuits.
This may make us think that DC LEDs are the better choice if they don’t need a separate driver to convert the current, but there are certain advantages of using an AC LED over a DC LED.
- AC LEDs can be dimmed with phase control dimmers, which are common in residential electrical wiring. However, for standard dimmers to work with a DC LED, you need to use a special power switching circuit that converts the energy from AC to DC before operating the LED light bulb. This adds more complexity (and cost) to the light bulb design, meaning that AC LEDs are usually cheaper than their DC counterparts.
The bottom line is, if you want simplicity and cost-effectiveness, go for an AC LED light bulb instead of a DC one. Choosing a recognised brand is important with LED bulbs and I always recommend companies like Sylvania lighting linked to on Amazon here.
Are 12V Halogen Lights AC or DC?
The 12v halogen lamp is an excellent example of how the AC power supply steps down the voltage via a transformer for the operation of the light. The transformer is powered by an AC voltage, and it generates a lower AC voltage (12V) supplied to the bulb.
The same principle applies to all other low voltage systems like those in your car and even in domestic main lights. In some low voltage systems, such as motor vehicle lighting, the source power supply may be in DC, so you will find both AC and DC transformers sitting on the same circuit board.
12v halogen lamps are typically fed from an AC supply via a transformer but will work just as well on DC. However, you need to make sure that there is sufficient power to heat the filament against the current limiting resistance of the lamp.
Are LED Christmas Lights AC or DC?
A few different LED Christmas light strings use either AC or DC power supplies but most of today’s LED Christmas lights use DC power supplies because of cost-effectiveness and reliability.
The type of power supply used depends on the design of the LED circuit and the LED driver. The LEDs themselves require a low voltage supply (3V to 3.2V), and each LED requires 20 mA to 30 mA current depending on the colour and brightness level.
Moreover, a series resistor is used to control the current in each string, usually in conjunction with an IC driver chip to boost or step down the input voltage to match that needed by the LEDs.
Christmas light displays typically have hundreds or thousands of LEDs connected in series strings, (like these epic ones on Amazon) powered from 230V AC voltage. Therefore, the input AC voltage needs to be rectified and converted into DC voltage before the LEDs can use it.
As you might imagine, this process has been done many times before and is more cost-effective than designing a new circuit for every new application. You can purchase an off-the-shelf power supply specifically for driving LED arrays with a single DC output.
Are Light Fixtures AC or DC?
Well, not all light fixtures use mains electricity. You can find a variety of solar-powered and battery-powered light fixtures. However, most light fixtures used in buildings and homes are AC.
AC Light Fixtures
Nearly all light fixtures receive power from Alternating Current (AC) power lines. A conductor, such as a metal wire, carries an electrical current resulting from an electromagnetic field. With AC, the direction of the electromagnetic field reverses at regular intervals, typically 50-60 times per second (called Hertz), so the voltage also alternates back and forth in the same way.
In a typical household circuit, AC power is supplied from a power utility through that company’s power lines to a transformer. The transformer reduces the voltage to what’s needed for your home’s electrical wiring and devices. In the United States, this is typically 110 or 120 volts for standard two-prong plugs and 230 volts in the UK for standard 3 pin plugs.
Therefore, most light fixtures work with AC voltages and currents. However, some lights run on DC voltages and currents, but these are less common.
Direct Current (DC) Light Fixtures
Some light fixtures, such as LED and low-voltage lights, are designed to receive direct current (DC) electricity. This is most commonly done in the form of an LED driver converting the current from AC to DC before it enters the light-emitting diodes.
DC lights are becoming much more popular due to their long life span and less energy consumption, but they are still powered by an AC supply to the fixture so I guess they are kind of a hybrid approach is the easiest way to look at it.
Also See: Is LED Ghosting Dangerous?
Conclusion
I hope that has helped answer the question, are LED lights AC or DC? In a normal domestic setting such as the LED light in your living room, it is most likely to be an AC supply from the fuse board to a LED driver within the light fixture which converts the AC current to DC and delivers it to the LEDs to produce the light. In a way, I guess they can be considered both AC and DC powered.
