UL 497:2017 PDF Download

The UL 497:2017 standard outlines the requirements for protectors used in paired-conductor communications circuits in accordance with Article 800 of the National Electrical Code.

The standard defines a communications circuit protector as a device that includes single- and multiple-pair air gap arresters, gas tube arresters, or solid state arresters, with or without fuses or other voltage-limiting devices. These protectors are designed to safeguard equipment, wiring, and personnel from excessive potentials and currents in telephone lines, caused by lightning, power induction, contact with power conductors, and rises in ground potential.

It is important to note that this standard does not cover lightning protective devices for secondary distribution wiring systems and equipment, antenna discharge units for radio and television receivers, lightning conductor and air terminals for building protection, protectors for fire alarm signaling circuits (covered by UL 497B), secondary protectors for communications circuits (covered by UL 497A), and transient voltage surge suppressors (covered by UL 1449).

Any product that deviates from the requirements outlined in this standard and presents a risk of fire, electric shock, or injury to individuals must be evaluated using additional component and end-product requirements to maintain the intended level of safety. If a product's features, characteristics, components, materials, or systems conflict with specific requirements of this standard, it does not comply with the standard, and necessary revisions must be proposed and adopted in accordance with the standard's development and revision procedures.