Question about POE

[hometownfl]

So I know that there are basically two different modes of POE, modes 1 & 2. Mode 1 is when the power is fed over the same two pairs of wires as the data and mode 2 is when power is fed over the spare pair. Is there any POE PSE out there that can do both modes at the same time?? In my mind this would essentially be 802.3at times two, resulting in almost 60W of power over Cat5. If there is an adapter to split this power at the end of the wire, then I'll be able to power any 60W device via Cat5.

 

[ex_bubblehead]

Nope.

The updated IEEE 802.3at-2009 PoE standard also known as PoE+ or PoE plus, provides up to 25.5 W of power. The 2009 standard prohibits a powered device from using all four pairs for power.

 

[POEEXP]

So I know that there are basically two different modes of POE, modes 1 & 2. Mode 1 is when the power is fed over the same two pairs of wires as the data and mode 2 is when power is fed over the spare pair. Is there any POE PSE out there that can do both modes at the same time?? In my mind this would essentially be 802.3at times two, resulting in almost 60W of power over Cat5. If there is an adapter to split this power at the end of the wire, then I'll be able to power any 60W device via Cat5.

yes , there are many devices that use "4 pair" high power solutions to power 60W and above by POE, without breaking the IEEE standard, you can check Cisco "UPOE" switches and Microsemi midspans "PD9501" or "PD9601" (95W for the new HDbaseT standard), both using 4 pair doubling the IEEE 802.3AT standard as you thought, over a regular cat5 cable.
you are limited to 51W at the user end with a source of 60W, due to the cable loses.

good luck

 

[danifel]

So I know that there are basically two different modes of POE, modes 1 & 2. Mode 1 is when the power is fed over the same two pairs of wires as the data and mode 2 is when power is fed over the spare pair. Is there any POE PSE out there that can do both modes at the same time?? In my mind this would essentially be 802.3at times two, resulting in almost 60W of power over Cat5. If there is an adapter to split this power at the end of the wire, then I'll be able to power any 60W device via Cat5.

Yes, it is possible and products that do that are available in the market today. Cisco calls this UPo (Universal PoE) and Microsemi/PowerDsine calls this 4-pairs PoE, or EEPoE. See http://www2.microsemi.com/PowerDsine/Products/Midspan/PD_9500G.asp and http://www.cisco.com/en/US/netsol/ns1190/index.html.
Both products do not infringe the IEEE802.3-2009 standard.

In addition to this the HDBaseT Alliance created Power over HDBaseT (PoH), which can deliver up to 95W over all 4-pairs.

 

[danifel]

Nope.

The updated IEEE 802.3at-2009 PoE standard also known as PoE+ or PoE plus, provides up to 25.5 W of power. The 2009 standard prohibits a powered device from using all four pairs for power.

If you look carefully at the stadnard you will note that the PSE section does not have such a preclusion. There is a note on the PD section that mentions that the PD cannot take opwer from both 1,2,3,6 and 4,5,7,8 at once., but that the PD has be able to take power from either. It is IMPOSSIBLE to make a PD that will take power from either but will not take power from both... so the note is an error in the spec.