Rosslyn, Va.-based National Electrical Manufacturers Association (NEMA) has published DC 3-2008, "Residential Controls — Electrical Wall-Mounted Room Thermostats," developed by NEMA’s Residential Controls Section. The revised standard, last published in 2003, covers self-contained, electrical and electronic, wall-mounted room thermostats for heating and/or cooling. It also provides specifications on rating and classification, construction requirements, and testing and performance requirements, including the equipment necessary to test thermostat operation and performance.

DC 3 was extensively revised to reflect changing technologies in heating and cooling systems and the increasing use of electronic controls. The standard also features a revised marking section and updates to the test chamber specification.

"Thermostats are the key control component in heating and cooling systems and the point of interface for users," says Dan O’Donnell, chair of the 3DC subcommittee for thermostats. "DC 3 provides specifications for the classification, testing, and performance of thermostats to ensure safe and reliable operation. These extensive revisions will prove very useful to the construction, property management, and utilities industries."

The standard may be downloaded at no charge from the NEMA Web site.