In an electrical schematic, how are operating controls generally represented?

In an electrical schematic, operating controls, such as switches or relays, are commonly represented as "Normally Open." This representation indicates that the circuit remains open during its standard state, allowing current to flow only when the control is activated.

This concept is particularly important in the operation of many devices, where a control actively engages to close the circuit and enable operation. For example, in a heating system, when the thermostat (an operating control) detects a need for heat, it closes the normally open contact, allowing current to flow to the heating elements.

Understanding that operating controls are normally open helps technicians recognize the default state of a device and anticipate the behavior of the system when control inputs change. It provides a clear visual representation of how components within the system interact under normal operating conditions, which is crucial for troubleshooting and installation tasks in gas systems and related equipment.