I have been looking at power over ethernet devices. I am having a problem understanding the terminology. I am reading that a PoE switch passes electric power to a powered device (PD). The definition given for PD is any device that is powered by PoE. That seems kind of ambiguous to me. It's probably just my brain has been burned out. I just need it stated in plain english. Can I expect to get power to any device I place downstream of a PoE device?

1. the device must be able to use ethernet as power source.
2. there are some limitations on current, you need to read the documentation (so you cannot use an "improved" iron as PD from a switch).

Power over ethernet is where power and data are run on the same ethernet cable. Power may be provided by a PoE switch or what is known as a power injector. A power injector combines voltage onto the ethernet cable. They are really designed for one device where as a PoE switch can power many.

If the PD is PoE capable then you do not need to use a separate power supply. When you plug in the ethernet cable the device is also powered.

For non PoE devices there are also what is known as power spliters. Basically the opposite of a power injector where you can then plug the power into a the PDs power plug.

For non PoE devices you also need to be aware if it's power and voltage requirements since they might not be compatible with PoE standards.

Okay so not every device is PoE capable natively.

This sounds kind of complicated.

Thanks!

Correct.

PoE is something like 48 VDC and can be as much as ~71 Watts depending on what standard the powering device supports. Splitters do have voltage regulators and many have switches to select for different outputs. If using a splitter with a non PoE device you also need to be aware of how it grounds its self.