UL 9540A sixth-edition thermal-runaway propagation test method, including vent-gas ignition and large-scale fire testing
UL 9540A, 6th edition (published March 2026)observed
| Value kind | observed — Reported measurements, counts, and specifications keep the precision and scope stated by their source; an exact specification is not treated as a range. |
|---|---|
| Scope | Published test method, not an ESS product listing or automatic installation approval. UL describes a January 1, 2027 effective transition for sixth-edition testing; verify applicability to the supplied certification/report. |
| As of | 2026-03-13 |
| Source | UL Code Authority, Understanding UL 9540A and NFPA 855; ANSI publication record dated 2026-03-13. · Sixth edition and effective-date transition discussion |
| Review | checking…review by 2027-01-01 · slow cadence |
| Recorded changes | last 2026-09-16 · 2 revisions tracked |
| Claim id | thermal-runaway-propagation-test-method-most |
Where the guide uses it
← Full numbers register — every date-stamped figure in the guide, with revision history.