🔍 Key Concepts

• Double-throw vs. single-throw switch – how many different ON positions or load/source connections can one handle select? • Look for ON–OFF–ON or a clear transfer between two different sets of contacts. • Internal view of the switch: trace whether the blades can connect to two separate terminals depending on handle position.

💭 Think About

• On each illustrated switch, ask yourself: does this handle only turn the circuit ON or OFF, or can it connect the circuit to one of two different paths? • Compare the internal hardware in B and C: which one clearly shows a transfer mechanism that moves between two distinct contact assemblies rather than just opening and closing one? • On the front covers (A and D), which labeling suggests more than a simple ON/OFF function, indicating two possible ON positions?

✅ Before You Answer

• Verify which devices clearly have two sets of stationary contacts for each pole, with a movable blade that can engage only one set at a time. • Check the front labels for ON–OFF–ON (typical of double-throw) versus just ON/OFF (single-throw). • Confirm which illustrations show a mechanism meant for transfer between two sources or loads, not just disconnecting power.