Capacitors in control circuits may retain dangerous voltages after power is removed, making it important to discharge capacitors before servicing.

Capacitors in control circuits may retain dangerous voltages after power is removed, making it important to discharge capacitors before servicing.

• A. False
• B. Not always
• C. High risk
• D. True

Answer: (D)

Capacitors store electrical energy, and that energy doesn’t disappear the instant power is removed. In control circuits you can have large capacitors in the DC bus, hold-up circuits, or snubbers that can keep a dangerous voltage for some time. If you touch or short the circuit without discharging them, the stored energy can release as a shock or cause damage. That’s why the practice is to discharge capacitors before servicing and to verify they’re at a safe voltage level. Some devices do have leakage or bleeder paths that reduce stored energy over time, but you should not assume they’re safe—always treat capacitors as capable of holding a dangerous charge until you’ve confirmed they’re discharged.

Capacitors store electrical energy, and that energy doesn’t disappear the instant power is removed. In control circuits you can have large capacitors in the DC bus, hold-up circuits, or snubbers that can keep a dangerous voltage for some time. If you touch or short the circuit without discharging them, the stored energy can release as a shock or cause damage. That’s why the practice is to discharge capacitors before servicing and to verify they’re at a safe voltage level. Some devices do have leakage or bleeder paths that reduce stored energy over time, but you should not assume they’re safe—always treat capacitors as capable of holding a dangerous charge until you’ve confirmed they’re discharged.