A ___ is commonly used in a holding circuit and is known as a holding contact.

In the context of a holding circuit, a normally open contact is essential because it allows the circuit to remain energized only when triggered by an input device such as a push button or switch that is momentarily activated. When the input device is engaged, the normally open contact closes, establishing a path for current to flow. This action is critical in holding circuits, where the objective is to maintain the operation of a load after the initial activation signal is removed.

The holding contact configuration relies on the principle that once energized, the contact will keep the load powered on until a specific condition is met (e.g., a stop button is pressed). In this way, it creates a self-sustaining loop for the current, which is why it is often referred to as a holding contact.

Other types of contacts, such as normally closed and momentary switches, do not provide the same function in a holding circuit. Normally closed contacts would serve to interrupt current flow rather than maintain it, and momentary switches do not sustain the current but rather only allow a temporary link while they are actively pressed. A SPST maintained switch, while it can hold a state, does not operate under the same principles as a normally open contact in maintaining a circuit without continuous manual input.