In the schematic, the main power supply across L1–L2 is:

In the schematic, the main power supply across L1–L2 is:

• A. 120 V
• B. 240 V
• C. 480 V
• D. 600 V

Answer: (B)

L1 and L2 are the two hot conductors of the supply, and the voltage across them is the line-to-line voltage the circuit uses. In a typical US split‑phase setup, those two hot legs are each 120 V relative to neutral and are 180 degrees out of phase, so the voltage between them is 240 V. That’s why the main power across L1–L2 is 240 V. A 120 V reading would come from measuring to neutral rather than across both hot legs, while 480 V or 600 V would point to a higher‑voltage system or a different configuration not intended for this circuit.

L1 and L2 are the two hot conductors of the supply, and the voltage across them is the line-to-line voltage the circuit uses. In a typical US split‑phase setup, those two hot legs are each 120 V relative to neutral and are 180 degrees out of phase, so the voltage between them is 240 V. That’s why the main power across L1–L2 is 240 V. A 120 V reading would come from measuring to neutral rather than across both hot legs, while 480 V or 600 V would point to a higher‑voltage system or a different configuration not intended for this circuit.