After isolating the high‑voltage service disconnect, what action should you take with the key?

• A. Remove the key and apply lockout/tagout.
• B. Leave the key in the switch.
• C. Hide the key and continue.
• D. Make a copy of the key.

Answer: (A)

After isolating the high-voltage service disconnect, the essential step is to secure the energy source so it cannot be turned back on while work is being done. Remove the key and apply lockout/tagout. The lock provides a physical barrier that prevents the switch from being closed, and the tag communicates that maintenance is in progress and identifies who is in charge of the control. This combination protects you and others from unexpected energization and helps ensure compliance with safety procedures.

Leaving the key in the switch would allow someone to re-energize the circuit, defeating the safety barrier. Hiding the key or making extra copies also undermines control and can lead to unapproved energization. By using a lockout/tagout system, you establish a verifiable safe state and reduce the risk of electric shock or arc flash during service.