# UL 539 — Which OSHA-recognized labs (NRTLs) can certify to a given test standard

For UL 539, standard title is Single and Multiple Station Heat Detectors; status is listed as appropriate, recorded from its source on 2026-08-10.

- **Test standard:** UL 539 _(verified: appears in the quote below)_
- **Standard title:** Single and Multiple Station Heat Detectors _(verified: appears in the quote below)_
- **Status:** listed as appropriate _(our reading, not quoted from the source)_

## What the source says

> UL 539 | Single and Multiple Station Heat Detectors |

## Source

- https://www.osha.gov/nationally-recognized-testing-laboratory-program/list-standards

Last verified: 2026-08-10. Review by: 2026-11-08.
Part of [Which OSHA-recognized labs (NRTLs) can certify to a given test standard](https://referencesource.org/nrtl-recognized-test-standards/).