In a residential split-phase 120/240 V system, what is the voltage between the two hot legs?

In a residential split-phase 120/240 V system, what is the voltage between the two hot legs?

• A. 120
• B. 240
• C. 277
• D. 0

Answer: (B)

In a residential split-phase 120/240 V system, each hot leg is 120 V relative to the neutral. The two hot legs are 180 degrees out of phase, so the voltage difference between them adds: 120 V + 120 V = 240 V. That’s why the voltage between the two hot legs is 240 V. The 277 V option doesn’t apply to typical homes (it’s used in certain commercial lighting systems from a different supply), and 0 V would only occur if the two points were at the same potential. So the correct result is 240 V.

In a residential split-phase 120/240 V system, each hot leg is 120 V relative to the neutral. The two hot legs are 180 degrees out of phase, so the voltage difference between them adds: 120 V + 120 V = 240 V. That’s why the voltage between the two hot legs is 240 V. The 277 V option doesn’t apply to typical homes (it’s used in certain commercial lighting systems from a different supply), and 0 V would only occur if the two points were at the same potential. So the correct result is 240 V.