To discharge a capacitor, which method is recommended?

To discharge a capacitor, which method is recommended?

• A. Short the terminals with a metal tool
• B. Use a 15,000 to 20,000 ohm, 2 to 5 watt resistor across the terminal
• C. Connect to power source
• D. Let it sit unplugged

Answer: (B)

Discharging a capacitor safely means giving it a controlled path to release its stored energy without creating sparks or shock. Placing a resistor directly across the terminals provides that controlled bleed. The high resistance limits the discharge current, so energy is released gradually rather than dumped all at once. Shorting the terminals with a metal tool creates an almost direct short circuit. The capacitor would try to dump its energy instantly, causing a large surge current, arcing, heat, possible damage to the capacitor or surrounding components, and a real risk of shock. It’s unpredictable and dangerous. Connecting it to a power source would keep it charged or even re-energize it, not discharge it. Letting it sit unplugged doesn’t guarantee discharge either; many capacitors retain a charge for a long time, and you could still be shocked when handling them. Using a resistor of about 15,000 to 20,000 ohms across the terminals provides a safe discharge path. The current is limited to a few milliamps, and the resistor dissipates the energy as heat in a predictable way (P = V^2 / R). With this setup, you’ll discharge it gradually to a safe voltage while keeping risk low. The wattage rating (2–5 W) ensures the resistor can safely handle the heat produced during discharge.

Discharging a capacitor safely means giving it a controlled path to release its stored energy without creating sparks or shock. Placing a resistor directly across the terminals provides that controlled bleed. The high resistance limits the discharge current, so energy is released gradually rather than dumped all at once.

Shorting the terminals with a metal tool creates an almost direct short circuit. The capacitor would try to dump its energy instantly, causing a large surge current, arcing, heat, possible damage to the capacitor or surrounding components, and a real risk of shock. It’s unpredictable and dangerous.

Connecting it to a power source would keep it charged or even re-energize it, not discharge it.

Letting it sit unplugged doesn’t guarantee discharge either; many capacitors retain a charge for a long time, and you could still be shocked when handling them.

Using a resistor of about 15,000 to 20,000 ohms across the terminals provides a safe discharge path. The current is limited to a few milliamps, and the resistor dissipates the energy as heat in a predictable way (P = V^2 / R). With this setup, you’ll discharge it gradually to a safe voltage while keeping risk low. The wattage rating (2–5 W) ensures the resistor can safely handle the heat produced during discharge.