Flashtubes operate at high voltages, with currents high enough to be deadly. Under certain conditions, shocks as low as 1 joule have been reported to be lethal. The energy stored in a capacitor can remain surprisingly long after power has been disconnected. A flashtube will usually shut down before the capacitor has fully drained, and it may regain part of its charge through a process called "dielectric absorption". In addition, some types of charging systems can be equally deadly themselves. The trigger voltage can deliver a painful shock, usually not enough to kill, but which can often startle a person into bumping or touching something more dangerous. When a person is charged to high voltages a spark can jump, delivering the high capacitor current without actually touching anything.