Serious injury can result from opening what type of disconnect that is energized with load current?

• A. Load-break Disconnect
• B. Maintenance Disconnect
• C. Non-load Break Disconnect
• D. Grounding Switch

Answer: (C)

Opening a disconnect that is carrying load current can create a bright, dangerous arc as the contacts separate and the current tries to continue. A non-load break disconnect is designed to carry current but is intended to be opened only when there is no current. If you try to open it while the line is live, an arc can form, posing a serious risk of burns, shock, and equipment damage. The other types are constructed to interrupt current safely (load-break) or are used for maintenance safety procedures (maintenance disconnect, grounding switch), so they aren’t the ones whose improper use under load would be the same kind of severe hazard.