Rotary LED dimmer switches offer sleek, intuitive control over your lighting, but their performance and safety depend significantly on how they are loaded. One of the most common issues in lighting installations arises from exceeding or miscalculating the maximum load that a dimmer can handle. This guide explains how to calculate load, why it matters, and how to avoid flickering, overheating, or failure.
Maximum load refers to the highest total wattage of light fixtures (bulbs) that can be connected to a dimmer switch without risking malfunction or damage. Exceeding this rating can lead to:
Flickering or pulsing lights
Dimmer overheating
Early dimmer or lamp failure
Electrical hazards
Most modern rotary dimmers are rated for different types of loads, depending on the technology in use (LED, halogen, etc.).
Lamp Type | Maximum Load (per gang) |
|---|---|
| Dimmable LED | 150W (up to 10 lamps) |
| Halogen/Incandescent | 400W |
Note: For LED, the number of bulbs matters more than the total wattage alone due to inrush current.
Identify the bulb type and its wattage.
For example, if you’re using 8W dimmable LED bulbs.
Multiply wattage by the number of bulbs.
Example: 8W × 6 bulbs = 48W total.
Check the dimmer’s max LED rating.
In this case, you're safely within the 150W LED max load.
Confirm that the total number of LED bulbs is within range
Even if total wattage is low, inrush current from too many LEDs can cause issues. Keep under the manufacturer’s recommended bulb count (10 max).
Unlike traditional bulbs, LED drivers can cause inrush spikes at the moment of switching on. These short bursts of high current don’t last long but can exceed what the dimmer is built to handle. This is why:
The number of LED lamps is often limited, even if they are low wattage.
You may experience flickering or no dimming at all if this is exceeded.
Some LEDs may not dim smoothly or may "jump" at certain brightness levels.
Mixing different bulb types (e.g., LED and halogen on the same circuit).
Installing too many LED bulbs even if wattage seems low.
Using non-dimmable LEDs – these will not function correctly with a dimmer and may damage it.
Underloading the dimmer – some models require a minimum load to function properly (usually 5–10W).
Use only dimmable LED bulbs with trailing-edge compatibility.
Stick with a single bulb brand and model per circuit for predictable dimming behaviour.
Adjust the minimum dim level using the rear potentiometer on the dimmer module to prevent flickering.
Consult bulb and dimmer compatibility charts provided by manufacturers.
If your lighting circuit exceeds the maximum LED load (wattage or lamp count), consider:
Splitting the lights into two or more circuits, each with its own dimmer.
Using a higher-capacity dimmer (if available and supported by your wiring).
Consulting a qualified electrician to assess and redesign the circuit.
If you are unsure about load calculations or experience issues like flickering or overheating, consult a qualified electrician or refer to the dimmer’s datasheet. For product-specific support, contact our technical support team.