LED Testing Reports Explained
LM-79, LM-80, TM-21 and ISTMT reports.
1. Why it matters
The reports behind an LED product are where marketing claims meet measured reality. LM-79, LM-80, TM-21, IES files and safety certificates each answer a different question, and a supplier who can hand you the right report for the exact model — not a similar one — is telling you the numbers are real. Learning to read them is the cheapest quality tool a buyer has.
2. What each report proves
| Report | Answers | Watch for |
|---|---|---|
| LM-79 | Measured lumens, efficacy, CCT, CRI, power of the fixture | Must be the exact model, accredited lab |
| LM-80 | LED package lumen maintenance over ≥6,000 h | At the drive current & temp you use |
| TM-21 | Projected L70/L80/L90 lifetime from LM-80 | Projection capped at 6× tested hours |
| IES / LDT file | Photometric distribution for layout software | Should match the LM-79 output |
| Safety cert (UL/CE/CB) | Electrical & fire safety compliance | Named model on the certificate |
3. Read the lifetime claim critically
"50,000 hours" is a projection, not a measurement, and it is only valid within limits. TM-21 lets a lab project lifetime to at most six times the LM-80 tested hours: 6,000 h of testing supports a claim up to ~36,000 h; a "100,000 h" claim from 6,000 h of data is extrapolated beyond what the standard allows and should be treated as marketing. Also check the temperature — lifetime is stated at a specified in-situ case temperature (Ts); run hotter and it falls fast.
- Check LM-80 was run at the current and temperature you actually drive.
- Confirm the TM-21 projection stays within 6× tested hours.
- Note the stated Ts — a claim at 55°C is void if your fixture runs at 85°C.
4. Confirm the report matches the product
The most common report fraud is not a fake document — it is a real report for a different (better) model, or an expired/withdrawn certificate. Cross-check the model number, wattage, CCT and CRI on the report against the datasheet and the physical label; confirm the lab is accredited (ISO/IEC 17025) and the certificate is current on the issuer's online database. If the report is for "series" but the specifics differ, ask for the report of the SKU you are buying.
5. Checklist
- Get LM-79, LM-80 and TM-21 for the exact model, not a series
- Verify LM-80 current/temperature match your operating point
- Reject lifetime claims beyond 6× the LM-80 tested hours
- Confirm the lab is ISO/IEC 17025 accredited
- Check the safety certificate is current on the issuer database