Open Forum → PoE over 4 wires with 10/100/1000 splitter... possible?

Wondering if this is possible, looking to find out before I go to the trouble of wiring it up..

To provide some context, my house is wired with single runs of Cat5e to multiple rooms in a home run wiring configuration (all wires terminate at the NID). I have ATT Uverse, and I need to return the phone line to the outside location to route it to another room (my RG is in the living room, wireless phone base station is in the bedroom). However, that room is also the room I need to run the PoE from.

So, what I'm looking to do is split that Cat5e, using two pairs for the voice and two for the PoE connection, probably on 3-6 in the jack. I know there are multiple standards for PoE, but from what I understand gigabit PoE (which is what I have, links to products below) simultaneously transmits data and power on the same lines (has to since 1000-t requires all four pair). The issue is that I don't really know what pairs gigabit PoE uses, and if it can just use 3-6 in the jack.

- Gigabit Injector - »www.amazon.com/gp/produc ··· F8&psc=1
- Gigabit Splitter - »www.amazon.com/gp/produc ··· F8&psc=1

Is this possible? Can you run PoE over just four wires? Would those be the central pairs? 1 and 2? 7 and 8?

Thanks,
Rick

you answered your own question, "has to since 1000-t requires all four pair". if you give up gig speed you can do it but to get gig you have to use all 4 pair.

Thanks for the response and for confirming my note. I figured it did (the spec seems to indicate it), but wasn't really sure.

The bigger question is really what pairs are used...? Does gigabit PoE run across all four pairs? Just two pairs? Or is it dynamic... meaning can it run on however many pairs are available without a power loss?

My concerns are:

- Even though gigabit PoE runs runs "with" data (shared), it could still just do that on the outside pairs (1/2, 7/8) and not the main/center pairs (3/4, 5/6)
- If it does run on all four pairs, it might still be possible that it does this by distributing load across all four... meaning removing two pairs could theoretically reduce the available power/wattage to the end device.

I just don't know enough about PoE, and I can't find anything online that tells me more specifically how gigabit PoE functions. Hoping someone on here has more than my rudimentary PoE knowledge...

Thanks,
Rick

»www.hkvstar.com/technolo ··· 3at.html it also depends on the poe standard used by the devices, 802.3af or 802.3at. so the specific pairs used will depend on the power supply and the equipment. mix them and you can let the magic smoke out. (been there done that)

regardless, if you are doing gig-e you need to run a new cable.

BTW, thanks for the link, great stuff. I'm still not really sure I understand the wiring scheme though... it seems to outline multiple scenarios for an injector/splitter combination (what I have). Do I need to figure out if my devices are using Option A or Option B? Or is that something the device does automatically based on the wiring configuration?

The specs for the TP Link gigabit PoE equipment don't indicate anything about Options... just 802.3af compliance and gigabit supporting.

Thanks,
Rick

then yours uses 802.3af and all equipment and wiring has to comply with that standard.

Ha, yeah, I'm not looking to create a fire risk on the back of my house.

The devices are 802.3af compliant for what it's worth. On the network side, I'm not actually concerned about losing gigabit on this run since the only thing I'll be connecting in the bedroom is the phone and the PoE injector. I also have another jack in that room that I could use in a pinch in the future (not in a location that will work for this unfortunately).

So the question, I guess, is if I wire two jacks using the four center pairs (3/4, 5/6) can I run phone over the one and PoE + 10/100 on the second? And if so, is that the wiring configuration to use?

Thanks,
Rick

if it supports mode A then yes you would be able to do that.

for the Telco pins 3&6 would be line 2 and 4&5 would be line 1. On the other jack you would use 1&2 and 3&6 for Ethernet/poe combined.

if it uses mode B then the voltage rides on the spare pairs and you can't use them. i made a mistake earlier thinking it was only different between af/at. see »en.wikipedia.org/wiki/Po ··· Ethernet