Master Electrician Practice Exam

What protection is required for 240-volt, twist-lock, 30-ampere receptacles on construction sites?

1. Surge protection

2. GFCI protection

3. Fused disconnects

4. Grounding connections

The correct answer is: GFCI protection

The requirement for GFCI (Ground Fault Circuit Interrupter) protection for 240-volt, twist-lock, 30-ampere receptacles on construction sites is critical in preventing electrical shock hazards. GFCI protection is designed to detect ground faults by monitoring the current flowing through the circuit. If an imbalance occurs — indicating that current is leaking through an unintended path, such as a person — the GFCI will quickly cut off the electrical supply, typically within milliseconds. This is especially important in construction environments where wet conditions and the use of portable power tools increase the risk of electric shock. Construction sites are inherently hazardous due to the presence of water, conductive materials, and wet conditions, making it imperative to enhance safety with GFCI protection. This requirement not only aligns with the National Electrical Code (NEC) which mandates GFCI use for specific receptacles on construction sites but also promotes a safer working environment for electricians and workers. While surge protection, fused disconnects, and grounding connections are important safety measures, they do not specifically address the immediate risk of ground faults that GFCIs are designed to mitigate. Grounding connections ensure the system has a path for fault currents, but they do not provide the same level of personal