UL 1277 2025-05 PDF

Full title and description

St UL 1277 2025-05 — Standard for Power and Control Tray Cables. This standard establishes construction, performance, marking and testing requirements for electrical power, control, and tray cables used in installations including industrial and commercial applications. It covers materials, conductor and insulation requirements, ampacity considerations, flame propagation, and environmental performance to ensure safe operation in building and industrial wiring systems.

Abstract

UL 1277 specifies safety and performance criteria for power, control, and tray cables intended for use in cable trays and in building installations. The document defines acceptable conductor types, insulation and jacket materials, tests for temperature, current-carrying capacity, mechanical durability, and fire performance. It is intended to reduce electrical hazards and ensure reliable long-term operation where these cables are installed.

General information

• Status: Published / Active (2025 revision)
• Publication date: May 2025
• Publisher: Underwriters Laboratories (UL)
• ICS / categories: 29.080.01 (Electrical wires and cables) / Safety standards; Electrical installation products
• Edition / version: 2025-05 revision
• Number of pages: ~60–120 (typical for UL cable standards; exact page count depends on published PDF)

Scope

This standard covers power, control, and tray cables intended for use in cable trays and for general wiring in industrial and commercial buildings. It applies to cables with various conductor configurations and sizes, intended for fixed installations at rated voltages typically up to 2000 V (check the standard for exact voltage ratings). Requirements include construction details, conductor and insulation materials, identification and marking, and a suite of performance tests—electrical, thermal, mechanical and flame propagation—relevant to safety during normal use and under fault conditions.

Key topics and requirements

• Construction requirements for conductors (copper, aluminum where permitted) and conductor stranding.
• Insulation and jacket material specifications, thicknesses, and physical properties.
• Temperature ratings and ampacity considerations for installed cables.
• Mechanical performance tests: flexing, impact, elongation, and tensile strength.
• Electrical tests: dielectric strength, insulation resistance, and short-time current tests.
• Flame and fire performance: vertical flame tests and limited flame propagation criteria for tray-installed cables.
• Environmental resistance: moisture, oil, and chemical exposure where applicable.
• Marking, labelling and packaging requirements for traceability and safe installation.

Typical use and users

UL 1277 is used by cable manufacturers, product designers, test laboratories, electrical contractors, specifying engineers, building inspectors, and regulatory authorities. Typical applications include power distribution and control wiring in industrial plants, commercial buildings, data centers, and installations where cables are routed in trays or raceways that require specified fire and mechanical performance.

Related standards

Related standards include other UL and IEC/IEEE standards for cables and wiring such as UL 1581 (Reference Standard for Electrical Wires, Cables, and Flexible Cords), UL 83, NFPA 70 (National Electrical Code) sections governing cable installations, and international standards for power and control cables. Project or jurisdictional requirements may also reference UL 1277 alongside local building codes and fire safety standards.

Keywords

UL 1277, power cable, control cable, tray cable, cable tray, insulation, jacket, conductor, flame test, ampacity, electrical wiring, cable standard, Underwriters Laboratories

FAQ

Q: What is this standard?

A: UL 1277 is a safety and performance standard published by Underwriters Laboratories that specifies requirements for power, control, and tray cables used in commercial and industrial wiring installations.

Q: What does it cover?

A: It covers construction, materials, marking, and a set of electrical, mechanical, thermal, and flame-performance tests for cables intended for installation in cable trays and similar fixed wiring applications.

Q: Who typically uses it?

A: Cable and component manufacturers, test labs, electrical engineers and designers, installers, and code officials use UL 1277 to design, test, specify and approve cables for building and industrial installations.

Q: Is it current or superseded?

A: The entry here refers to the 2025 revision (May 2025). Confirm with the publisher for the absolute current status and any amendments or corrigenda.

Q: Is it part of a series?

A: UL 1277 is one of several UL standards addressing wires and cables and is often used in conjunction with reference standards such as UL 1581 and applicable building and electrical codes; it complements other industry standards for specific cable types and installations.

Q: What are the key keywords?

A: Power cable, control cable, tray cable, cable tray, insulation, jacket, conductor, flame propagation, ampacity, UL 1277.