I am no expert on this, I thought the pixelnet was 4 paires of wire, how would the lights turning on and off. The power is not on the pixelnet, power is only after the hub, and on the 16 port hubs the signel is repeated. Then there is something about 485, it is diferential curent.
The signal for one pixelnet universe is sent over one pair... pixelnet+ and pixelnet- (like the dmx signal).
The EtD generates 4 pixelnet universes and so it uses 4 pairs. A (de)combiner or smart hub is able to break out the 4-pairs into individual universes.
Pixelnet can also be available over cat5 as "powered pixelnet". Only one pair is used for signal, and the other 6 wires are used for power (12v+ and ground). The before sending pixelnet over the 16 rj45 hacks, the smart hub pulls off one pair from the incoming 4 pairs and replaces the remaining 6 wires with power.
BTW: one reason why a longer distance can exist between hub and the SSCs is that the DMX signal is sent over a twisted pair. the SSC sends out 2 wires with power and one wire with data -- no longer a twisted pair for the data -- and that limits its range.