Reverse Phase Dimming LED Driver

Choosing a compatible dimmer for this LED driver.

This information is relevant to Armacost Lighting dimmable electronic power supply models 810602 & 810601. Some compatible dimmers have certain advantages or disadvantages so please refer to the technical notes below the chart. ELV dimmers made by Lutron will have ELV in the model number; all Legrand dimmers listed have programming capability that lets you select Reverse Phase ELV dimming.

Reverse Phase ELV Dimmers

Unlike standard dimmers, Reverse Phase dimming technology was created and engineered to work with electronic (solid-state) power supplies and transformers that supply power to low voltage lighting. ELV Reverse Phase dimmers eliminate voltage spikes via a gentler surge of current, making them more conducive to and easier on the power supply’s electronic circuitry. Armacost Lighting AC dimmable electronic power supplies work very nicely with Reverse Phase ELV type dimmers.

ELV type or Electronic Low Voltage dimmers does not mean they operate on 12V low voltage, ELV comes from the advanced circuitry needed within the dimmer to control electronic power supplies/transformers that step down 120V AC line voltage to the 12V DC your LED lighting requires. All ELV Reverse Phase dimmers require a neutral wire connection.

Because of the newer technology, Reverse Phase ELV dimmers are typically more expensive than standard incandescent Triac Forward Phase dimmers, and they must often be purchased online as they are not readily available in most home improvement stores.

Advantages and Disadvantages

  • Very responsive and provides extremely smooth dimming control
  • Designed and optimized for dimming electronic power supplies; are better at handling the inrush current. In theory, your dimmer and power supply will last longer
  • ELV dimmers require no real “trim” adjustments on the lower brightness setting. Thus, the dimming range may be perceived as a bit limited (15-100%)
  • Never any flicker or shimmer, no pop-on or drop-out
  • At lowest level brightness setting, LEDs still remain “on,” providing some level of light output
  • ELV dimmer performance is the brightest when at 100% (unlike some other dimmers which take away or limit some light output at full brightness)
  • Can be considerably more expensive than standard forward phase dimmers
  • Not all models are readily available in stores and must be purchased online

Forward Phase Universal Dimmers

Forward phase dimmers, also known as Triac or Leading Edge dimmers, are traditionally used with incandescent bulbs. They are much more common and less expensive but only a few newer models effectively work well with Armacost Lighting’s AC electronic dimmable LED power supplies. Models that do perform well include Lutron’s newer line of C•L Dimmers. Although these dimmers use Forward Phase control, they have been specially engineered to work with CFL and LED bulbs to reduce or eliminate many of the problems seen with brightness control when using older existing incandescent dimming technology.

Advantages and Disadvantages

  • Low cost and often can be purchased locally at many home improvement stores
  • Dimmers feature an adjustment dial where you need to set the dimming range to eliminate flicker or shimmer when dimmed very low and/or to adjust the brightness to be just above the level at which the LED light cuts out when dimmed. This can create a broader range of perceived dimming
  • Forward Phase dimmers can be load sensitive, the dimming range could be reduced if the total watts is less than 40% of the rated capacity of the power supplies
  • To some extent, some Forward Phase dimmers will not allow LEDs to achieve full brightness. Depending on the dimmer, LED load, and other conditions, overall light output may be reduced by between 3-10%. This is a typical benefit of all eco-style dimmers and will extend LED life and save energy
  • Not quite as smooth as ELV Reverse Phase dimmers; can be perceived as more of a “stepped”-style dimming
  • More susceptible to occasional AC line noise which could cause some flicker or shimmer to LEDs when set at certain very low levels of lighting. Perception of issue depends on local conditions and may be temporary and/or may not be perceived by an individual’s eyes

Of all the Forward Phase dimmers tested, Armacost Lighting recommends Maestro digital dimmers, models MACL-153M or MRF2-6ND-120. Except for losing some top end brightness at the 100% setting, these dimmers performed as smooth as Reverse Phase ELV dimmers.