Phase Cut Dimming for Solid State Lighting

The National Electrical Manufacturers Association (NEMA) has published NEMA SSL 7A-2013 Phase Cut Dimming for Solid State Lighting: Basic Compatibility.

This standard provides compatibility requirements when a forward phase cut dimmer is combined with one or more dimmable LED Light Engines (LLEs). An LLE comprises one or more LED modules, LED control gear (integral or remote), and a connection to the mains circuit. This includes both screw-in integrated LED lamps, as well as fixtures which contain separate LED drivers.

NEMA SSL 7A-2013 is meant to reduce the testing burden by utilizing synthetic loads and waveform generators to represent LLEs and dimmers during testing. All dimmers and LLEs tested against the criteria set forth in SSL 7A will be compatible with one another, without the need for specific testing of every lamp and dimmer pairing. In addition, it supports modern digital dimmers by providing dimmer power supply current requirements for compatibility with LLEs.

The requirements do not limit its use to any specific lighting product type or application. The standard was developed with input from global participants and includes requirements for a range of supply voltages and frequencies, making it suitable for global use. For the purposes of this standard, “compatibility” means:

  • The reliability of the dimmer and LLE are not affected by combining them.
  • Dimming behavior meets or exceeds the behavior specified in the standard.

NEMA SSL 7A-2013 is forward-looking and is intended to be used to design and qualify dimmer and LLE products (including integral or remote control gear) for use with each other. It is not intended for use to determine compatibility with existing products or the installed base of LLEs and phase cut dimmers.

View the contents and scope of NEMA SSL 7A-2013. A hard or electronic copy may be purchased for $54 by visiting, or contacting IHS by phone at 800-854-7179 (U.S. only) or 303-397-7956 (international).

NEMA is the association of electrical equipment and medical imaging manufacturers, founded in 1926 and headquartered in Arlington, Virginia. Its member companies manufacture a diverse set of products including power transmission and distribution equipment, lighting systems, factory automation and control systems, and medical diagnostic imaging systems. Worldwide annual sales of NEMA-scope products exceed $120 billion.

10 Jul