🔍 Key Concepts

• Understand the difference between normally open (NO) and normally closed (NC) contacts in schematics • Recognize the basic thermostat / temperature-controlled switch symbol versus a plain limit switch • Note how a change-of-state device is shown with an added temperature or sensing element mark on the contact symbol

💭 Think About

• First, identify which of the numbered symbols clearly show a temperature- or sensing-related mark added to a basic contact symbol—these are candidates for a thermostat • Next, among those candidates, decide which one shows the contacts in the closed position when no stimulus (no over‑temperature) is applied • Compare the shape and position of the moving contact: does it touch (closed) or not touch (open) the fixed contact in its normal state?

✅ Before You Answer

• Verify which symbols are definitely just plain switches with no extra sensing mark and rule them out • Check that the thermostat symbol you choose is shown as closed in the normal state (line actually touching the other contact) • Confirm that any extra line/triangle/loop attached to the contact represents a temperature element, not pressure or flow (look for consistency with other symbols on the sheet)