Dimmable and Non-Dimmable LED bulbs

Many retrofit LED bulbs are sold in two types; dimmable and non-dimmable. You should choose the correct type for your lighting circuit.

Dimming LED bulbs can save more energy and changes the visual appearance and feeling of your space. You can use a dimmable led bulb in a non-dimmable circuit. But you can NOT use a non-dimmable lamp in a dimmable circuit as it may cause damage to the lamp and or circuit. Integral bulbs are clearly marked as dimmable or non-dimmable on the packaging and on the lamp.

Matching old and new

Most dimmers installed today are designed to be used with high-power circuits to drive traditional filament bulbs which were all quite uniform and dimmable by just a voltage change. LED bulbs on the other hand are low-power and more complex. An LED bulb is a solid-state product that has built in circuitry (called a driver) that takes high-voltage AC input current and converts it to low-voltage DC current to drive the LEDs. Furthermore driver specifications are not uniform across the LED industry.

They are many different types of dimmers installed in homes and offices of various specifications (e.g. resistive; leading-edge and trailing-edge and electronic). So when using new LED bulbs with existing dimmers there is a matching of old technology with new which can be challenging.

The driver in dimmable LED bulbs may work with many types of dimmer but not all, for instance LED bulbs tend to work better with trailing-edge dimmers rather than leading-edge dimmers, but an existing dimmer may have a minimum load that is too high for an led bulb, e.g. A 60W filament lamp may use a dimmer that has a minimum load of 25W the replacement LED has a power rating of 6.5W - below the level required by the dimmer. Dedicated LED dimmers have a very low minimum power rating. 

The dimming experience can be different with LED. Overall the LED dimming performance is regulated by the capability of the LED driver/chip and the compatibility of the dimming circuit. Since there are a huge number of possible combinations of bulbs and dimmer, it is not be possible to have led bulb that works in all dimming environments.

LED currently have a lower dimming range than a filament lamp – LEDs currently dim down to about 10% of the total light output whereas filaments may go down to 1-2%.  Low-voltage transformers as used with MR16 12V spotlights also add to the complexity

Some of the issues that may occur when a dimmer is incompatible with a led bulb are:

• Flickering - Bulbs will flicker (can also occur if a non-dimmable lamp is used)
• Drop-out - No light output at the end of the scale
• Dead travel - When the dimmer is adjusted there is no matching change in light output (light may not dim to acceptable level)
• Not smooth - Light output may not go from dim to bright linearly
• Multiple bulbs - issues may become apparent when multiple bulbs are added
• Damage or failure - LED driver, circuit or LED is damaged or fails.
• Load below minimum - The power load of the led bulb is below the minimum required by the dimmer
• Mixed models- Different models of LED will likely have different drivers - since drivers behave differently this could result in dimming issues.

What can I do about dimming LED bulbs?

• Ideally upgrade your dimming circuit with good quality dimmers designed for LED - easy to do for new LED installations. This is a good investment for the lifespan of your led bulb.
• Make sure you purchase the correct dimmable or non-dimmable LED for your type of circuit
• Check our compatible dimmer list
• Change you circuit from dimming to non-dimming if not used much
• Remove transformers used with 12V MR16 bulbs and convert to 240V GU10 bulbs in the same fitting by changing the lamp holder (should be completed by an electrician)
• You should consider buying the same model and brand of led bulb for all the fittings in an area of a room (all bulbs will have the same driver)
• It would also be a good idea to buy spares - LED technology (as with other technologies such as mobile phones) is always improving and changing.

Please consult a qualified electrician to make any changes to your circuit.

Credit: integral-led.com