All components of a device that are in contact with the electric current must be isolated or protected, and when this is not possible, they should be supplied at low voltage, between 120 volts DC (ripple free) and 50 volts AC, because the human being is not prepared to withstand the effects of the current in the body. Regarding lighting, some AC-DC power supplies are included with the Safety Extra Low Voltage. The SELV is a system whose secondary circuit is designed and protected that under normal and fault conditions, the voltages do not exceed a safe value. This circuit has no direct connection to the primary power and derives its power via a transformer or an equivalent isolation device. Briefly, if the power supply is integrated with SELV, the occurrence of failures will not result in electric shocks because it is electrically separated from the earth and other systems and it includes suitable electric isolation. This system is integrated in most Brilumen power supplies.