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DOE Revises Report on Dimming LEDs

Trouble over dimming solid-state lighting (primarily LED) is one of those puzzles that persist despite best efforts to resolve them. The need to dim LED lighting using phase-cut dimmers raises compatibility issues because some LED light engine technologies work better with the traditional dimmers than others.

The U.S. Department of Energy (DOE) put out a report in October 2013 titled Dimming LEDs with Phase-Cut Dimmers: The Specifier's Process for Maximizing Success, which addresses the compatibility issues and seeks to establish best practices for making sure the installed lighting performs as expected. DOE issued an updated version of that report this week that now recommends a National Electrical Manufacturers Association (NEMA) lighting standard, NEMA SSL 7A-2013 Phase Cut Dimming for Solid State Lighting: Basic Compatibility.

DOE’s report specifies that for wall-box installation, a NEMA SSL 7A-compliant dimmer be used with compliant LED sources. Pairing these products guarantees a level of compatibility and ensures the dimmer will not negate the dimming claims of the lamp or luminaire.

This is one of the Gateway reports put out periodically by the DOE’s Energy Efficiency & Renewable Energy (EERE) office showing solid-state lighting in real-world case studies to glean lessons designers, specifiers, installers and users learned along the way. The study explains in good detail how phase-cut dimmers designed to control incandescent lamps interact with LED replacement technology and the compatibility problems that arise. It includes both general guidance and step-by-step procedures for designing lighting control systems with phase-cut dimmers that will work.

“Compatibility alone does not guarantee dimming quality characteristics such as lack of flicker, smoothness, or a specific minimum dimmed level. These characteristics are best evaluated by observation, which is why mockups are so strongly recommended,” the DOE report executive summary points out.

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