Multiple POE over a single cable

Question

I try to solve a problem using Power Over Ethernet technology to Power supply differents devices. I would like to avoid to buy new router and try to make it work without any expensive costs (if possible). Let me explain you the situation :

I have a POE compatible router which is in a room, let's call it room A and 2 IP cameras which are in another room, let's call it room B. Cameras are POE compatible.

I have a single cat 5 ethernet cable which link both rooms together. A single router port provide 15W and a single camera need 15W.

I would like to power supply my cameras from my router over a single cable. Is there any possibility to use 2 ports (30W) on my router from room A over this single cable and split this power (2x15W) from room B for both cameras.

Is it possible and is there eventually ethernet split connectors which exist to do that ?

Thank you for the help.

Answer 1

I know this is an older question, hopefully you've solved it by now, but I wanted to toss in my two cents, for the benefit of future generations if nothing else.

First of all, yes, ethernet and PoE specs mean you can do exactly what you're trying to do, and run two PoE cameras over a single Cat5e.

First up, there are very, very, VERY few IP surveillance cameras that use gigabit ethernet; 99.99% of them are 10/100 Fast Ethernet only. The ones that do use GbE will be super high-end, super high-res, and super expensive.

Second, very very few cameras use more than about 5-6 watts. Most IR cameras won't pull more than about 4W with the IR on; non-IR cameras will typically use 2W or less. To use a full 15W you'd be looking at something with massive IR range, heater, fan, and probably PTZ as well. The Axis outdoor cameras I use, with internal heater and fan to dissipate moisture, spec a maximum 12.1W draw.

With all that in mind: 10/100 ethernet uses only two of the four pairs, and PoE "mode A", aka "endspan" runs power over that same pair. This means that if your switch and cameras both support Mode A or endspan power (which will include most except the very cheapest), you can run a camera over only two pairs.

That leaves the other two pairs free for a second device - I've run a second camera that way, a IP video decoder, a wireless access point, a room temperature monitor...

On the switch end, I'll often just strip the jacket back 2-3", terminate the orange and green pairs normally in one RJ45 plug (n that case, for T-568B, the plug would look like white/orange, orange, white/green, blank, blank, green, blank, blank), and then put the brown and blue pairs where the orange and green pairs would go in a second plug (I use brown for orange and blue for green, just to keep it simple to keep track of). The two can then plug into adjacent ports in the switch. If you prefer to split the two out into adjacent keystone jacks and use standard patch cords, you can do that too.

On the other end, you can split the pairs out in a box and terminate into keystones, then run patch cords to the cameras... or bring it in behind one camera, put plugs on the ends and plug one into that camera, then run an extension to the other camera and put a keystone on it to connect to your home run.

Of course, you can adjust the termination types to suit your purposes. In a pinch I've just used "beanie" connectors to splice the wires - at the end of the day, they're still just moving electricity.

Now some PoE switches will do up to a full 15W per port, but for only half the ports, and more typically provide 7.5W per port... but again, with most cameras, that will be more than enough, and again, that's per port - you're plugging each camera into its own port here, so that's not a problem.

Yes, this is all very "non-standard"... but it is certainly possible, easy to do, and so far it's worked very reliably for me when there have been no other options.

Answer 2

If 100 Mbit/s is enough for camera to work, You can try split single 4-pairs cat5 cable in two 2-pairs links. It can be done by 2 Ethernet splitter or by proper cable crimping. "This adapter brings 4-5-7-8 to the second port's 1-2-3-6. This is, technically, a spec violation, but over short distances, it does work."

100BASE-TX Ethernet works definitely, but PoE in question, because method B of PoE not work in this case and both can depends on power loss in long cables (method A for 1G Ethernet use all 8 wires to power delivery).

It depends on method of PoE injection

PINS on Switch  10/100 DC on Spares (метод B)   10/100 Mixed DC & Data (метод A)
Pin 1           Rx+                             Rx+ DC+     
Pin 2           Rx–                             Rx– DC+ 
Pin 3           Tx+                             Tx+ DC– 
Pin 4           DC+                             not used
Pin 5           DC+                             not used
Pin 6           Tx–                             Tx– DC– 
Pin 7           DC–                             not used
Pin 8           DC–                             not used

Answer 3

Get a 802.3at injector which can supply 30Watts over the single cable, then use a POE powered switch in room B to split the signal and power to your two cameras. The 802.3af cameras will only pull what they need from the 802.3at as they negotiate power demands if they follow the standard.