Which action is essential before servicing circuitry?

• A. Increase power to test a fault.
• B. Only rely on automatic protection.
• C. Replace components without turning off power.
• D. De-energize circuits before servicing.

Answer: (D)

De-energizing circuits before servicing is essential. Turning off power and disconnecting the circuit removes the risk of electric shock, arc flash, or unexpected energization while you work. In practice, power down, unplug if possible, apply lockout/tagout if available, and discharge any stored energy (like capacitors) before touching components. Even if protections exist, they aren’t a substitute for turning off power, and attempting to diagnose or replace parts while the circuit is live can cause harm or damage. This safe step is the baseline for any circuit work.