ROSSLYN, Va. - The National Electrical Manufacturers Association (NEMA) has revised its standard DC 3-2003, "Residential Controls-Electrical Wall-Mounted Room Thermostats." At the same time, the trade association's Residential Controls Section has reaffirmed for continued use DC 10-1983 (R1989, R2003), "Residential Controls-Temperature Limit Controls for Electric Baseboard Heaters," and DC 20-1992 (R2003), "Residential Controls-Class 2 Transformers."

DC 3-2003 covers self-contained, electrical and electronic, wall-mounted room thermostats for heating and cooling. It provides specifications on ratings and classification, construction requirements, and testing and performance requirements, including the equipment necessary to test thermostat operation and performance.

DC 10 covers the construction requirements and characteristics of temperature limit controls and controls systems of either the auto or manual-reset types that may be mounted inside electric baseboard heaters in order to disconnect the electrical load due to high temperatures.

DC 20 provides suggested requirements for the construction and performance of Class 2 transformers designed primarily for use in 30 volts rms maximum low-voltage residential control circuits.

"NEMA's Residential Controls Section has reviewed and revised DC 3," said Don Donnelly, chairman of the section, "in order to provide the industry with a uniform method for testing that yields performance data for comparison to requirements."

DC 3-2003 may be viewed or purchased for $41 at DC 10 may be viewed or purchased for $36 at DC 20 may be viewed or purchased for $41 by visiting

Publication date: 03/08/2004