FCC Technician Exam Question Of The Day (T0A12)

Q) What kind of hazard might exist in a power supply when it is turned off and disconnected?

A) You might receive an electric shock from stored charge in large capacitors

NJ2X Notes:
Capacitors store electrical energy.  This energy can be released quickly through contact and are thus a shock hazard.

• Avoid working on energized electrical equipment or circuits. 
• Test capacitors with a suitable voltmeter and discharge before working on or near them.
• Use suitable insulators during the discharge process.
• After discharging the capacitor verify that there is no residual charge with a suitable voltmeter.