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1. What is IES LM-79 Test?
IES LM-79 (full title: IESNA LM-79-19) is a solid-state lighting photometric & electrical measurement standard issued by the Illuminating Engineering Society (IES) of North America, updated to the latest 2019 edition. It is the core mandatory testing specification for LED luminaires accessing North American market and applying for DLC, ENERGY STAR and UL certifications.
For LED high bay lights, LM-79 testing objectively quantifies critical performance metrics including luminous flux, efficacy, intensity distribution, CCT and CRI. It serves as authoritative performance proof for downstream buyers and a fundamental prerequisite for North American commercial channel access.
Core Standard: IESNA LM-79-19 (valid current version: 2019) Scope: Complete solid-state lighting fixtures (high bay, street light, flood light, panel light, etc.) Test Ambient Condition: Ambient temperature: 25°C ±1°C; Relative Humidity ≤65%
2. Core Test Parameters of LM-79
表格
| Parameter | Definition | Unit |
|---|---|---|
| Luminous Flux | Total visible light output emitted in all directions by luminaire | lm (lumen) |
| Luminous Efficacy | Luminous flux generated per unit input power | lm/W |
| Luminous Intensity Distribution | Spatial luminous intensity data for IES file generation | cd (candela) |
| CCT (Correlated Color Temperature) | Color appearance of light source (warm / neutral / cool white) | K (Kelvin) |
| CRI / Ra | Color rendering capability with full score 100 | Dimensionless (0~100) |
| Input Power | Actual active power consumption of finished lamp | W (Watt) |
| Power Factor | Ratio of real power to apparent power | Dimensionless (0~1) |
3. Comparison of Two Mainstream LM-79 Test Methods
表格
| Test Method | Integrating Sphere | Goniophotometer |
|---|---|---|
| Applicable Luminaire Size | Max. 1/5 diameter of integrating sphere | Large-size fixtures: high bay, street light |
| Main Test Content | Total luminous flux only | Full-space intensity distribution + total flux |
| Output Document | Flux test report | Standard .ies photometric file |
| DLC / ENERGY STAR Preference | Only acceptable for small lamps | Preferred for complete luminaire certification |
4. Detailed LM-79 Test Procedure
Step1 Sample preparation & pre-aging: Prepare 2~3 representative samples and age for minimum 100 hours. Step2 Test environment setup: Stabilize ambient temperature at 25°C±1°C, block stray ambient light; preheat testing equipment over 30min. Step3 Electrical parameter measurement: Record input voltage, current, power and power factor. Step4 Photometry test: Full-spatial scanning via goniophotometer to calculate total flux and luminous efficacy. Step5 Colorimetric test: Measure chromaticity coordinate, CCT, CRI and R9 via spectroradiometer. Step6 Standard IES file generation: Export photometry data into industry-standard .ies format per IESNA specification. Step7 Report issuance & audit: Formal LM-79 test report released by NVLAP-accredited laboratory.
5. Linkage between LM-79 Test & Global Certifications
表格
| Certification Program | LM-79 Mandatory | Lab Qualification Requirement | Remarks |
|---|---|---|---|
| DLC QPL Listing | Required | NVLAP accredited lab | LM-80 report required together |
| ENERGY STAR | Required | NVLAP accredited lab | ISTMT thermal test report additionally needed |
| UL 1598 Safety Certification | Supplementary | UL recognized lab | Focused on product safety compliance |
| IEC CB Certification | Supplementary | IECEE CB Scheme lab | Corresponding standard: IEC 62722-2-1 |
6. Key Compliance Notes
- For DLC application, LM-79 reports must be issued by NVLAP-certified labs and dated within prior 36 months before submission.
- Actual tested luminous flux ≥90% of marked nominal value; actual input power ≤110% of rated power; measured CCT shall fall within ANSI chromaticity tolerance ellipse.
- Generated standard .ies file can be directly imported into professional lighting simulation software: DIALux, AGi32, Relux etc.
7. FAQ
Q: Relationship between LM-79 test and UL certification? A: LM-79 covers photometric & electrical performance testing while UL focuses on product safety assessment; they complement each other. Valid NVLAP LM-79 report is compulsory for DLC listing application.
Q: How long does LM-79 testing take? A: Standard lead time: 2~4 weeks including mandatory 100-hour pre-aging and over 30min equipment preheating under controlled 25°C±1°C environment.
Q: Required sample quantity? A: Minimum 2~3 test specimens; final report is calculated based on average test data of all submitted samples.
Q: Validity period of LM-79 test report? A: No statutory expiry date for the report itself, yet DLC & ENERGY STAR mandate reports issued within latest 3 years. Retest is required once product design or component is revised.
Disclaimer This document is AI-assisted for reference only and shall not be deemed certification commitment or legal advice. All implementation shall follow the latest official IES and regulatory standards.
