Exposed connections can be lethal. Potential injury to eyes and body parts from arcing.
A 30 MFD, 600 VDC capacitor is charged by a high voltage power supply for about 10 seconds. Put one end of a metal rod, which has an isolated handle such as a screwdriver, on the post of the capacitor, and let the other end of the rod close to the other post of the capacitor. A spark will occur.