# UL Standards: UL 857, Busways

> Publisher listing for the busway product standard, fourteenth edition published September 10, 2025. Establishes that the scope covers busways and associated fittings including tap boxes, feed boxes and plug-in devices. No requirement, clearance, rating or marking text is reproduced here.

Canonical page: https://datacenterlabeling.com/references/s63

Original source: [UL Standards: UL 857, Busways](https://www.shopulstandards.com/ProductDetail.aspx?productId=UL857_14_S_20250910)

## Scope of this source

Publisher listing for the busway product standard, fourteenth edition published September 10, 2025. Establishes that the scope covers busways and associated fittings including tap boxes, feed boxes and plug-in devices. No requirement, clearance, rating or marking text is reproduced here.

Establishes the busway product standard, its current edition and date, and that its scope covers plug-in devices and tap boxes. It does not establish what a field identification label should say.

Rackstamp provides editorial field guidance. IDs, cases, and worksheet entries are fictional examples unless identified otherwise. Distinguish local conventions from adopted standards. Source notes describe the evidence scope; a linked overview is not the full standard or a project approval.

## Related guidance

- [Nobody can tell which tap-off box feeds which rack](https://datacenterlabeling.com/problems/busway-tap-off-identification)