Residual Voltage

Residual voltage test
This test confirms that no dangerous voltages are present as a result of circuits holding a charge after the supply has been removed. After removal of the mains supply the time for the stored voltage to fall below 60 V is measured. This time must be less than five seconds for equipment permanently wired into the mains. Opening an interlocked cover should cause the exposed voltage to decay to less than 42.4 V peak or less than 60 V DC or less than 20 joules energy level within two seconds. Where the residual voltage is present on the pins of a plug or socket, the conductors of which are unprotected, after plug-socket separation (i.e. not IP2X) the voltage must decay to 60 V in less than one second. Exemptions to this requirement are components having a stored charge of 60 mC or less, since such energy levels are not harmful.