All the following are true of 240-volt systems compared to 480-volt systems, except:

All the following are true of 240-volt systems compared to 480-volt systems, except:

• A. They cost more to operate.
• B. They require more current per unit of power.
• C. They require smaller circuit breakers.
• D. They are safer.

Answer: (C)

Voltage and current are inversely related for a given load: P = V × I. If you maintain the same power, increasing the voltage lowers the current. So delivering the same load at 240 volts requires more current than at 480 volts. Circuit breakers protect by limiting current. A higher current means a larger ampere rating, so to feed the same load, a 240-volt system would typically need a bigger breaker than a 480-volt system, not a smaller one. That makes the statement about smaller circuit breakers the false one in this comparison. Other statements align with the physics: at the same load, 240 volts draws more current, which tends to raise I^2R losses in conductors and can raise operating costs compared to 480 volts. And while lower voltage reduces shock severity, the safety of a system depends on many factors, but lower voltage is generally considered safer than higher voltage, all else equal.

Voltage and current are inversely related for a given load: P = V × I. If you maintain the same power, increasing the voltage lowers the current. So delivering the same load at 240 volts requires more current than at 480 volts.

Circuit breakers protect by limiting current. A higher current means a larger ampere rating, so to feed the same load, a 240-volt system would typically need a bigger breaker than a 480-volt system, not a smaller one. That makes the statement about smaller circuit breakers the false one in this comparison.

Other statements align with the physics: at the same load, 240 volts draws more current, which tends to raise I^2R losses in conductors and can raise operating costs compared to 480 volts. And while lower voltage reduces shock severity, the safety of a system depends on many factors, but lower voltage is generally considered safer than higher voltage, all else equal.