Some contributors have expressed concern about damage to existing equipment etc. This should not be a problem. The standard defines a method for determining whether a node is PoE-ready, and only applies 48V to those nodes. Other nodes just see the "discovery" signal - a current-limited voltage in the 2-10V range.
The standard also includes plenty of other protection mechanisms - current limiting, power limiting, disconnecting when the load changes.
The power supplies at the user end are specified as isolated, with a 1500V isolation barrier. And the IEEE engineers, who spent 4 years slaving on the technical aspects of the spec, conducted extensive tests with legacy equipment to ensure power could not be inadvertanty applied.
I'm putting together a web site on the technology - see www.PowerOverEthernet.com (early days yet) - there is an introductory article at http://www.poweroverethernet.com/articles/000008.h tml - contributions to that site are welcomed!
Slashdot Mirror
Some contributors have expressed concern about damage to existing equipment etc. This should not be a problem. The standard defines a method for determining whether a node is PoE-ready, and only applies 48V to those nodes. Other nodes just see the "discovery" signal - a current-limited voltage in the 2-10V range. The standard also includes plenty of other protection mechanisms - current limiting, power limiting, disconnecting when the load changes. The power supplies at the user end are specified as isolated, with a 1500V isolation barrier. And the IEEE engineers, who spent 4 years slaving on the technical aspects of the spec, conducted extensive tests with legacy equipment to ensure power could not be inadvertanty applied. I'm putting together a web site on the technology - see www.PowerOverEthernet.com (early days yet) - there is an introductory article at http://www.poweroverethernet.com/articles/000008.h tml - contributions to that site are welcomed!