# ANSI C57.12.21 — Which OSHA-recognized labs (NRTLs) can certify to a given test standard

For ANSI C57.12.21, standard title is Pad Mounted Compartmental-Type Self-Cooled Single-Phase Distribution transformers with High Voltage Bushings; 167 kVA and Smaller; status is no longer recognized, recorded from its source on 2026-08-10.

- **Test standard:** ANSI C57.12.21 _(verified: appears in the quote below)_
- **Standard title:** Pad Mounted Compartmental-Type Self-Cooled Single-Phase Distribution transformers with High Voltage Bushings; 167 kVA and Smaller _(verified: appears in the quote below)_
- **Status:** no longer recognized _(our reading, not quoted from the source)_

## What the source says

> ANSI C57.12.21 | Pad Mounted Compartmental-Type Self-Cooled Single-Phase Distribution transformers with High Voltage Bushings; 167 kVA and Smaller |

## Source

- https://www.osha.gov/nationally-recognized-testing-laboratory-program/standards-no-longer-recognized

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/).