Types of Dimmers Each type of lighting source (load types) has individual characteristics, which require special types of dimmers. It is important to use a dimmer that is designed, tested, and UL listed for your specific lighting source/load type:
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Incandescent/Halogen: Line-voltage tungsten filament lamps, including line-voltage (120 V) halogen lamps | |
| Electrical characteristic | Resistive | | Special requirements | Rated for cold filament inrush (positive and negative periods may not be equal, resulting in a net DC voltage). Do not use on magnetic low-voltage (MLV) or Electronic low-voltage (ELV). |
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Magnetic Low-voltage (MLV): Magnetic (core and coil, toroidal) transformer-supplied low-voltage lighting (6, 12, or 24 V) | |
| Electrical characteristic | Inductive
| | Special requirements | Symmetric cycles (VDC ≤ 2), smooth turn off (positive and negative periods are equal for safe MLV transformer operation). Include transformer losses when calculating the load. |
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Electronic Low-voltage (ELV): Electronic (solid-state) transformer-supplied low-voltage lighting | |
| Electrical characteristic | Capacitive
| | Special requirements | Very smooth turn on. Neutral wire connection |
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Neon/Cold Cathode (Magnetic Ballast): Magnetic (core and coil, toroidal) transformer-supplied
| Electrical characteristic | Very inductive
| | Special requirements | Symmetric cycles (VDC ≤ 2), smooth turn off (positive and negative periods are equal for safe MLV transformer operation). Include transformer losses when calculating the load. Low end trim capability. |
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Fluorescent: Electronic Fluorescent Dimming Ballast Special dimmers are designed and UL listed to send power and control signals to each type of electronic fluorescent dimming ballast.
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Light Emitting Diode (LED): Electronic LED Driver Special dimmers are designed to send power and control signals to each type of electronic LED driver.
| Special requirements | LED light source must be properly matched to LED driver, and LED driver must meet control specifications for control type (e.g. IEC for 0-10 V). |
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Heat Dissipation During normal operation, dimmers get warm to the touch. Wallbox dimmer efficiency is typically around 99%. The other 1% is dissipated in the dimmer as heat. So, a 600 W load on a 600 W dimmer would produce around 6 watts of heat. This is approximately the heat generated from a small nightlight. Operating on its rated load, Lutron dimmers will stay below the UL limits of 140º F (60º C).
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Ganging & Derating To help the dimmer dissipate the internal heat normal to operation, a typical dimmer is wider than a switch. Dimmers can be ganged together such that the space is the same as switches. A portion of the fins (heat sink) must be removed. The fins are grooved to make the removal of fins easy with a pair of pliers. The removal of fins reduces the wattage capacity (load) the dimmer can control.
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Magnetic Low-voltage Dimmer Ratings The stated VA (volt-ampere) rating is the capacity of the dimmer that includes the magnetic transformer heat losses and the lamp load. A Lutron MLV dimmer UL listed for 1,000 VA can be loaded with a full 1,000 VA lamp load. A transformer dissipates up to 20% of the connected load as heat. Better transformers dissipate less than 10% as heat. Added together, the lamp load and the transformer loss determine the dimmer capacity required.
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Electronic Low-voltage Dimmer Ratings Electronic low-voltage transformers also dissipate some heat. These inefficiencies are small enough to be accounted for in the dimmer rating. A Lutron ELV dimmer UL listed for 600 W can be loaded with a full 600 W lamp load. If ganged with other dimmers, standard derating rules apply.
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