The HP 620 redundant/external power supply provides redundant system power and/or an extra power over Ethernet (PoE) power for each of two supported switches simultaneously. Ideally suited for Voice over IP (VoIP) environments, the 620 provides the RPS and extra PoE power needed in many other common customer environments where high power availability is desired. Switchover from a failed internal power supply to the 620 is seamless and immediate. In addition, the 620 can protect against a single power main failure by being connected to a different power main than the switch.