Issuing body: UL

UL 891

Switchboards

UL 891 covers dead-front switchboards rated nominally 1000 V or less, for installation per the National Electrical Code, the Canadian Electrical Code Part I, and the Mexican installations standard, with available short-circuit current up to 200,000 A. It excludes theatre preset and dimmer control, live-front construction, railway control and electrification equipment, and constructions intended only to receive motor control centre units. The structural difference from the IEC world is conformity assessment: UL 891 means listing by a nationally recognised testing laboratory with follow-up inspection, where IEC 61439 rests on the manufacturer's declaration backed by design verification.

UL 891 carries its own listing and its own verification evidence, so the North American route is planned separately and early.

Official source — UL →

Technical background

Standards

Which busbar standard applies to your job

A decision tree from product type, voltage class and destination market to the governing standard set, with each standard placed at its actual scope boundary.

Standards

UL 891 versus IEC 61439 for busbar fabrication

Scope, conformity assessment, temperature-rise limits, spacings and short-circuit withstand compared, and what the differences change in the busbar shop.

Standards and compliance

UL 857