Final answer:
The neutral wire in a three-wire system serves as the return path for the current. In this case, the neutral wire is grounded to zero volts and safe to touch. To determine the size of the neutral wire, calculate the total current flowing through it, which is 125 amps. Consult a wire ampacity chart to find the appropriate wire gauge for this load.
Step-by-step explanation:
The neutral wire in a three-wire system serves as the return path for the current to complete the circuit. In this case, the neutral wire is connected to ground at the voltage source and the user's location, forcing it to be at zero volts. The neutral wire is also grounded to the case of the appliance through the green ground wire.
Therefore, the neutral wire in this scenario is safe to touch even without insulation.
In order to determine the size of the neutral wire, we need to calculate the total current flowing through it. Since the main load is drawing 100 amps on 230 volts, we can use the formula P = IV to find the power consumed by the load: P = 100 amps × 230 volts = 23,000 watts.
The other load drawing 50 amps on 115 volts consumes 50 amps × 115 volts = 5,750 watts. The total power consumed by both loads is 23,000 watts + 5,750 watts = 28,750 watts. Since power is the product of current and voltage (P = IV), we can rearrange the formula to solve for current: I = P/V. Therefore, the total current flowing through the neutral wire is 28,750 watts / 230 volts = 125 amps.
Based on the total current of 125 amps, the neutral wire should be sized to handle this amount of current. The size of the neutral wire is typically determined by the ampacity, or carrying capacity, of the wire. Consulting a wire ampacity chart, we can find the appropriate wire gauge for a 125 amp load.