LM-79 Testing


The Gamma Scientific Laboratory, NVLAP Lab Code 200823-0, has been awarded accreditation by the National Voluntary Laboratory Accreditation Program (NVLAP) under the Energy Efficient Lighting Products Program. This includes LM-79 accreditation for Solid State Lighting Luminaires – Total Flux Measurements (Luminous Efficacy) and Solid State Lighting Luminaires –Luminous Intensity Measurements.

Our accreditation also includes IES LM-80:2008 for Solid State Lighting Luminaires-Lumen Maintenance (SSL Life Tests).

The Gamma Scientific laboratory is also on the LED Lighting Facts® Approved Labs List.

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Gamma Scientific NVLAP Scope of Accreditation

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LM-79 Definition and Scope

IES LM-79 is an approved method for testing electrical and photometric measurements of solid-state lighting products. LM-79 contains procedures for performing reproducible measurements of LEDs properties, including: total flux, electrical power, efficacy and chromaticity.

The scope of LM-79 applies to LED products that incorporate control electronics and heat sinks. This covers complete LED luminaires and integrated LED sources. It does not include bare LED chips or LED based products without a light source.

LM-79 testing requires complete luminaire testing on an absolute photometric basis. Typically lighting products are evaluated on a relative photometric basis, where separate tests are done for lamps an luminaires. However, for solid state lighting products the LED lamps typically cannot be separated from their luminaires. The absolute photometric testing required measures the light distribution and light intensity of the complete luminaire.

LM-79 Procedures and Conditions

  • Ambient Conditions
    • Maintain temperature at 25 degrees C +/-1 degree C (within 1M)
    • Mounting – limit thermal transfer
    • Limited air flow
  • Power Supply
    • AC waveshape limit to harmonic RMS of 3%
    • Voltage regulation to +/- 2%
  • Seasoning and Stabilization
  • Testing Orientation
  • Electrical Settings
  • Instrumentation

LM-79 Test Outputs and Calculations

  • Total Luminous Flux
  • Luminous Intensity Distribution
  • Electrical Power
  • Luminous Efficacy
  • Chromaticity
  • CCT
  • CRI

LM-79 Test Methods

Integrating sphere systems are used to measure the total luminous flux and color for LM-79. This can be performed with a photometer (total luminous flux) or a spectral radiometer (spectral radiant flux). Utilizing a spectral radiometer and integrating sphere is the preferred method, which derives total luminous flux and color qualities form spectral radiant flux measurements.

Goniophotometer systems are also used for LM-79 testing to measure luminous intensity distribution. The Goniophotometer system tests derive total luminous flux and provide color characteristics including CCT and CRI.

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