How to Choose the Best LED Strip Light Power Supply
Choosing the right power supply for LED strip lighting can be a bit trickier than you’d expect. Factors such as wattage and voltage play key roles in the selection process, and oftentimes, there is more than one power supply that will work for your particular project. This article aims to give you all of the information necessary to feel confident that you have what’s needed to power your LED strip lights.
What does an LED light strip power supply do?
LED strip lights typically operate at a low voltage of 12V or 24V DC, but most homes and buildings supply 120V AC. A strip light power supply converts the higher AC voltage to the lower DC voltage required by the LED strip lights.
What to consider when choosing a power supply:
When choosing the right power supply, you’ll need to know these four things:
- The power consumption of your strip measured in watts per foot
- The length of LED strip lighting your project requires
- The voltage of your strip
- If you want your power supply to be dimmable
The best way to determine which power supply you need is to look at the power rating of the strip light you wish to use. We use this general rule of thumb:
Make sure your power supply’s rated wattage is at least 20 percent higher than the total wattage of your LED strip light. To calculate this, follow this formula:
Length of LED strip (measured in feet) x watts per foot / 0.80 = minimum rated LED power supply required to power your strip light
This will give you the minimum-sized power supply you’ll need to run your strips. Because power supplies are available in a variety of wattages, you’ll take the number you came up with and find the closest power supply that has a wattage rating higher than that number.
Let’s take a look at a step-by-step example:
- You’re looking to install 22 feet of under-cabinet lighting in your kitchen.
- The strip consumes 3.5 watts per foot.
- Multiply 22 feet by 3.5 watts per foot.
- The total is 77 watts—meaning your strip draws 77 watts of power.
- Then, to follow the 20 percent rule, divide 77 watts by 0.80 to get 92.4 watts. Dividing by 0.80 provides a 20% headroom to prevent your power supply from overheating and failing prematurely.
- This means that you will need a power supply that is rated for at least 92.4 watts.
- Because power supply wattages are offered in varying increments, you’ll need to round up and find a power supply rated greater than 92.4 watts.
You can run strips on a power source rated higher than the amount needed. In fact, if you decide to add more LED strip lighting to your project in the future, having more power will come in handy. Our LED strips already have current-limiting resistors built into the strip, so they will only draw as much current as they require. The extra wattage of the power supply will not be used, which will allow your lighting system to run cooler and more efficiently. If you run your power supply over its capacity, this will cause it to overheat or fail prematurely.
It’s also important to verify that the output voltage of the power supply you choose is compatible with the voltage of your LED strip lighting. Also, be sure that the power supply’s input voltage matches that of the location it will be installed in. For example, if you have an LED strip with 12-volt DC operation that you wish to use in a 120-volt AC home wiring system, you’ll need a power supply that includes 120 volts in its input range and has 12-volt DC output.
Another factor to take into account for longer runs is voltage drop. A significant voltage drop is present after a certain distance of the LED strip. After this distance, there will not be enough voltage present to light the next length of the strip. This varies depending on the type of strip and length being used. Please refer to “Max Run” in the specifications table of the strip light to determine how long a strip can be run continuously without a parallel run back to power. Or, check out our blog post explaining how to prevent voltage drop over long runs.
Now that you know the necessary wattage and voltage output of your power supply, you can determine if you want your power supply to be dimmable or not. If you wish to adjust the brightness of your strip light, you’ll need to be sure that the power supply you choose is capable of dimming. You could also attach a PWM controller to a non-dimmable power supply to achieve the same effect. For more on how to choose the best dimmer for your strip lights, check out this post.
If you’re still not sure which power supply to use for your LED strip lighting project, reach out to our technical support team or customer service department at 866-590-3533. Our teams are available from 8:30 a.m. to 6 p.m. CT Monday-Thursday and 8:30 a.m. to 4 p.m. CT on Friday.