UL 1996:2021 PDF Download

The UL 1996:2021 standard covers the requirements for fixed electric duct heaters and their remote control assemblies. These heaters are rated at 600 volts or less and are intended for use in ordinary locations as defined by the National Electrical Code.

However, it is important to note that this standard does not cover other electric heating equipment or appliances such as fan-coil units, central heating furnaces, radiant heating equipment, electric boilers, baseboard heaters, or air heaters. These equipment fall under separate and individual requirements.

For duct heaters intended for use in hazardous locations, compliance with this standard must be evaluated along with the requirements for hazardous location equipment specified in other applicable standards.

Duct heaters designed to be connected to air-duct systems should be installed in accordance with the installation standards for air conditioning and ventilating systems (NFPA 90A) and warm air heating and air conditioning systems (NFPA 90B).

The standard also includes requirements for relays and other auxiliary control devices that may be provided as part of a duct heater. These devices are evaluated considering their compatibility and interaction with other heating or cooling equipment.

A duct heater, as defined in this standard, is a self-contained heater installed in the air stream of a ducted system, external to the air-moving unit. It requires an adequate flow of air from a separate fan or blower system. The heater can be installed in the main supply duct or one of the branch ducts. Group installations of two or more duct heaters in close proximity are permissible if tests confirm acceptable performance based on the manufacturer's instructions.

In cases where a duct heater is used in conjunction with another source of heat, its compliance with this standard is assessed, and further examination and tests are conducted to determine the acceptability of the combination.