Lexi Avanzato
Lighting Services Inc
Lighting and Controls Applications Engineer
Has This Ever Happened To You?
You have done your research and confirmed that the dimmer you have just purchased is compatible with your LED fixtures. When it comes time to test out the performance, you’re not seeing what you were expecting. This is because compatibility is just one part of the dimming puzzle. The dimmer you have has several electrical requirements that must be met in order to ensure proper performance. Two of these requirements are minimum and maximum loads.
Minimum Loads
Dimmers have minimum load requirements because if the LED load isn’t drawing enough current to keep the dimmer’s switching elements closed, the dimmer will have unpredictable behavior. This behavior can include flickering, reduced dimming range, flashing when off, or not even working at all.
Dimmers that are designed for incandescent loads tend to have a larger minimum load requirement because incandescent fixtures generally have higher wattages than LED fixtures. This means that these dimmers will most likely require multiple LED fixtures to meet the minimum load requirement. Testing is necessary to determine the exact number of LED fixtures needed for each incandescent dimmer. Dimmers that are designed for LED loads usually have a lower minimum load requirement and typically only require one or two fixtures. The LED minimum load rating for LED load dimmers is usually given in number of lamps instead of Watts (W) or Volt Amps (VA).
Maximum Loads
Dimmers also have maximum load requirements to ensure the load does not exceed the dimmer’s design limits. Surpassing these limits can result in premature dimmer failure, flickering due to noise, as well as breaker tripping. One of the main reasons dimmers have maximum loads is because of the inrush current caused by LED drivers. Inrush current is input current of short duration during initial start-up that exceeds the steady-state current value. The graph above shows the current waveform when a device is powered up.
Because of this inrush current, an LED may be rated as 25W but the actual wattage initially going through the dimmer is much higher. This means that if an incandescent dimmer is rated at 600W, you can’t assume you can use twenty-four 25W LED fixtures. A good rule of thumb is to allow 100W for each LED fixture so in this case, the 600W dimmer can handle only six LED fixtures.
Low-End Trim
If you are meeting all of the electrical requirements of the dimmer and you are still having flicker issues, you can try adjusting the low-end trim. Adjusting the low-end trim raises the minimum dimming level which will reduce the chance of flickering and drop-out. This will only solve the flickering issue if you are trying to dim the fixtures lower than the dimming control range of the driver.
How to adjust the low-end trim will be explained in the instruction manual of the dimmer you are using. Usually, it will be as easy as turning a dial, shown below:
Summary
Minimum and maximum load requirements differ between incandescent fixtures and LED fixtures. To determine the actual load requirements for a particular dimmer and fixture, testing must be done. Even when meeting the load specifications, flicker may still occur if you are trying to dim lower than the rating of the LED driver. Adjusting the low-end trim of the dimmer may resolve this.
https://www.dimmers.net/cfl_led_dimmers.asp
http://www.lutron.com/TechnicalDocumentLibrary/367-2035_LED_white_paper.pdf
FAQs
Minimum and maximum loads for dimmer switches
A 0-400w Incandescent or Halogen dimmer may have a 10-100w loading when used in conjunction with an LED light source. This means that the total wattage of LED's on the dimmer must not exceed 100w but just as importantly must have at least 10w of load on it.
How many LED lights can a dimmer control? ›
A good rule of thumb is to allow 100W for each LED fixture so in this case, the 600W dimmer can handle only six LED fixtures.
What is the maximum wattage for a LED dimmer? ›
Maximum Wattage Load
Generally speaking, you will be looking for either 600 watt max load or 1000 watt. When choosing dimmers for dimmable LEDs or CFLs, you should not load a dimmer higher than approximately 25% of the rated load for the dimmer.
What does maximum dimmable load mean? ›
Dimmer is rated 100W-400W
Dimmer Min Load: 100W / 10 = 10W. Dimmer Max Load: 400W / 10 = 40W. This means that when this dimmer is used in conjunction with LED light bulbs, the load must be between 10W – 40W. Then, add up the combined wattages of the LED light bulbs to find out how many can be supported by this dimmer.
What is the maximum load for Lutron dimmer? ›
You'll notice Lutron allows the use of a connected lamp load rated up to 2000 watts. Due to the inherent voltage drop of Lutron dimmers, a combination of lamps with a total manufacturers specified rating of up to 2000 watts at 120 volts may be used on Lutron Commercial dimmers.
How to calculate LED dimmer load? ›
A rule of thumb commonly used to calculate a load for LED dimmers is to divide the stated maximum load by 10. For example a 400W dimmer switch should have no more than 40W of LED bulbs connected to it, which would equate to eight 5W bulbs.
Can LED lights be dimmed very low? ›
LED lights may be dimmable or non-dimmable. So if you're looking to buy a dimmable LED light, simply check the product description or product listing if you're shopping online. Manufacturers are encouraged to place this information prominently on their products as more customers are requesting this functionality.
Can you overload a LED dimmer switch? ›
If you overload the dimming switch the lights will not dim correctly and there is the potential to cause damage to the dimmer.
What happens if you use the wrong dimmer with LED lights? ›
Not all dimmers are compatible with LED lights, and using an incompatible one could cause flickering, reduced lifespan of your LEDs, or they might not even dim properly at all.
Do I need a special dimmer for LED lights? ›
There are different types of dimmers for each light technology. To this extent, only dimmable LED lamps can be dimmed and only with an LED dimmer. The different internal driver sets a minimum and maximum load that determines the dimming potential of the lamps.
For the best possible compatibility, look for a dimmer that includes a trim wheel, like the Cloudy Bay In Wall Dimmer Switch for LED, our pick for best for LED lights. The trim wheel allows you to adjust the switch to stop flickering and unwanted noises, if your bulbs aren't compatible right out of the box.
What happens if you put a non-dimmable LED bulb in a dimmer? ›
You can use a dimmable LED lamp in a non-dimmable circuit. You should NOT use a non-dimmable lamp in a dimmable circuit as it may cause damage to the lamp and or circuit. Integral lamps are clearly marked as dimmable or non-dimmable on the packaging and on the lamp.
How many LED lights can be on a dimmer switch? ›
Varilight recommend putting no more than 10 LED lamps on one dimmer module. You can put multiple lamps on one plate, so if you have a three gang dimmer plate you can put thirty LED lamps on the plate in total (10 on each module).
How to choose the right dimmer switch for LED lights? ›
Calculate The Total Load
For example, if a dimmer is rated 200W-600W, the minimum load would be 20W and the maximum load would be 60W. This means that when using LED light bulbs, the load must be between 20W and 60W. To find out how many bulbs can be supported by a dimmer, add up the wattages of all the bulbs.
Which is better leading edge or trailing edge dimmer for LED lights? ›
These more modern dimmers have many benefits over the leading edge type. These improvements include smoother dimming with less buzzing and interference. Trailing edge dimmers have a much lower minimum load than the leading edge, making them far more suitable for powering LEDs.
Do you need a certain dimmer for LED lights? ›
You'll know the compatibility of your dimmer switch through its type and minimum/maximum load range. As mentioned earlier, leading-edge dimmers are best suited for incandescent and halogen bulbs, while trailing-edge dimmers are ideal for LED lights.
How low can you dim an LED? ›
Traditionally, LED lights can dim up to 10%. But with the advancements in LED technology, some LED lights can now dim down to 1%. This just gets better since the lower the dimming range the longer the life of a LED bulb.
What is the minimum load for Lutron Caseta dimmer? ›
SECTION (1): CHOOSING THE CORRECT DIMMER
| MODEL | VOLTAGE/PHASE | MINIMUM LOAD |
|---|
| PD-5NE | 120V FORWARD OR REVERSE PHASE | 10 W |
| SEE APP NOTE #599 |
| SEE APP NOTE #599 |
| PD-10NXD | 120V FORWARD PHASE | 25 W |
13 more rows
