NEC Commercial Electrical Practice Test

In three-way and four-way switch configurations, all switching must be done in which circuit conductor?

1. Neutral

2. Grounded

3. Ungrounded

4. Service

The correct answer is: Ungrounded

In three-way and four-way switch configurations, all switching must be done in the ungrounded conductor, also known as the "hot" conductor. This is essential for proper circuit operation because the switching mechanism controls the flow of electrical current to the load; therefore, it needs to interrupt the ungrounded conductor to open or close the circuit properly. When switches are placed in the ungrounded conductor, they ensure that the load is fully disconnected from the power source when the switch is turned off, reducing the risk of shock or electrical hazards. If switches were placed in the grounded conductor or the neutral, it could create a situation where the circuit appears to be off, but the load remains energized, presenting a serious safety risk. The function of the ground and neutral conductors is different; the neutral serves as a return path for the current, while the ground provides a safety pathway to prevent shock. Therefore, properly controlling all switching through the ungrounded conductor is a fundamental safety and operational principle in wiring practices, as stipulated by the National Electrical Code.