What voltage must be used for smoke detectors in new residential constructions?

For new residential constructions, smoke detectors typically require a voltage of 120 volts AC to operate. This standardized voltage is widely used for hardwired smoke detectors, ensuring they have a constant power supply directly from the residential electrical system. The use of 120 volts AC helps to guarantee that these safety devices function reliably, as they are often interconnected to provide alerts throughout the home in case of smoke or fire detection.

Utilizing 120 volts AC also aligns with electrical code requirements that mandate smoke detectors be powered by the electrical system in most residential applications. This voltage level is sufficient for the units to function correctly while allowing for swift installation and compliance with safety regulations. Furthermore, many smoke detectors may have battery backup systems incorporated for added reliability during power outages.

Other voltage levels listed, such as 12 volts AC or 24 volts AC, are more commonly associated with specialized low-voltage systems, which would not be suitable for general residential use. Meanwhile, 240 volts AC is usually reserved for larger appliances and is not applicable for smoke detectors in typical residential settings.