Bell wire is a low-voltage, multi-purpose wire commonly used for doorbell circuits, thermostats, and other light-duty signaling applications.
Bell wire is typically an 18 or 20 AWG solid copper conductor designed for simple, low-voltage systems carrying around 24 volts or less. It often features a PVC jacket and comes in two-conductor or multi-conductor forms, with color-coded insulation to help identify polarity or circuit designation. While originally intended for electric doorbells, its use extends to thermostats, intercoms, and other low-power control circuits. Bell wire is not suitable for high-current loads, harsh environments, or applications requiring shielding or advanced code compliance, where specialized low-voltage cables are preferred.
Bell wire installations may be subject to the National Electrical Code (NEC) and Underwriters Laboratories (UL) guidelines, particularly in commercial applications.
The term "bell wire" originated from its early use in powering electric doorbells in homes and small businesses. Over time, the wire became a go-to option for other low-voltage signaling functions. Although more advanced cables are now preferred in complex systems, the name continues to be widely recognized in the industry.