120V halogen/incandescent dual dimmer to avoid overheating and possible damage to other equipment, do not use to control receptacles, fluorescent lighting fixtures, motor-operated or transformer-supplied appliances. Dimmer requires separate wires in the wallbox for each light circuit. When no grounding means exist within the wall box the NEC 2008, Article, 404.9 allows a dimmer without a grounding connections to be installed as a replacement as long as a plastic, noncombustible wallplate is used. For this type of installation, cap or remove the green ground wire on the dimmer and use an appropriate wallplate such as the Lutron's Claro series wallplates.