PoE (or Power over Ethernet) allows for devices to operate without the need for a separate power adapter, as the power is provided by a PoE switch. Based off the IEEE 802.3af-2003 standard, PoE provides up to 15.4 watts of power. IEEE 802.3af-2009, called PoE+ provides 25.5watts of power. PoE is very useful for wiring devices such as video cameras and wireless access points. PoE is standardised to adhere to specific voltage ranges between 37 and 57 volts. This ensures that any PoE device connected to a system receives a compatible power supply.