What is the normal limit control circuit voltage of a heating system?

In a typical heating system, the normal limit control circuit operates at 120 volts. This lower voltage level is designed to enhance safety and minimize shock hazards in residential and small commercial applications. The 120-volt control circuits are widely used in heating systems, including furnaces and boilers, because they provide sufficient power to control relays and switches without exposing users or technicians to the higher voltage levels used in the main power supply.

The use of 120 volts in limit control circuits also allows for easier integration with standard household electrical systems, which are typically designed to operate at this voltage. This voltage level ensures the reliable operation of various components, such as thermostats and limit switches, which are critical for maintaining safe and efficient heating.

In contrast, higher voltages like 240 volts and 480 volts are typically found in larger commercial heating systems or industrial applications where greater power is necessary to drive larger equipment. Options like 60 volts do not correspond to standard practice in heating systems and are likely used in different contexts, such as some specialized industrial equipment or older systems.