Do RJ45s need to be wired differently to enable POE (Power over ethernet)?

From experience (and I mean I have spent weeks figuring out why some PoE cables don't work and others do) I can say this: Ensure that your use RJ45 type B wiring and not type A for PoE. In some cases I have not been able to get type A to work. The power is transmitted, the powered device comes on, but there's no communication with the device, not even on layer2 (powered device MAC address is not visible on the switch).

So, use type B.

On a short cable (a few meters) it makes no difference, but on 70m+ it does. Using CAT5/5e or CAT6/6a cable, both cause problems on type A but not type B.

Although this is not strictly a wiring issue, to further explain the problems that can be experienced with CAT6 cable over long length (50m+), eejim writes at https://community.ubnt.com/t5/UniFi-Wireless/Unexpected-PoE-Cable-length-limitations-with-UniFi-Switch-16/m-p/1918103/highlight/true#M226319:

"CAT6/6A cables are being made with 26 gauge cable.

The biggest problem with 10Gb ethernet is crosstalk between the wires/pairs in the cable. There's just one way to lessen this - move the wires physically farther apart. One way the cable manufacturers have found to accomplish this while not making the cable too large - there is actually a spec for the maximum diameter of ethernet cable - is to make the copper wire itself smaller, so the insulation is thicker, so there's more space between conductors. This actually works (and they love it because there's less copper which saves them money, but they can charge more for the cable because, well, it's spec'd higher, right?) , but it causes the problem you are seeing - the smaller conductor has higher resistance and therefore more voltage drop than the standard CAT5e 24 gauge wire. So with longer CAT6 cables the PoE limitation needs to be accounted for. This is why I never use Cat6/6A cables except for very specific things, and never ever for PoE.

Change out your cable to CAT5e and the problems will go away. And at gigabit speeds it will work just fine up to 100 meters, even at 24V PoE."

Just to clarify an issue raised in other answers: Using the same cable with type A wiring POE doesn't work, but crimping type B wiring works. No theoretical arguments needed. This is a practical solution to real problem.

Having taken note of eejim's comments, I have checked with suppliers and there is a better quality CAT6/CAT6A available that uses 23 gauge wire, which will not suffer from these issues when used for POE purposes.

As others have commented/answered, the "wire layout" (i.e. the color code) doesn't matter, the cable type (5/5e/6) determines signal properties (i.e. how far the signal can travel and at what "speed", etc.) so as long as the cable is POE capable (any 5+ cable, or CAT3 if less power is needed) and the switch/device is POE compliant (802.3af-at), the "color code" of the wire is more for any one coming up behind you to know your scheme (i.e. if it's wired all wonky, you might not be able to quickly tell if one cable is a pass-through or crossover ... not fun when 1 cable can stretch 200+ feet and there are 200 cables to dig through)

FYI: The "standards" that most use are the TIA/EIA 568 A/B termination standards.

Based on the standards diagram posted in another answer and sourced from Wikipedia, the POE issue with crossover cables comes if the device using POE is using the Mode A standard - which puts biased power over the data pins. If the data pins reverse then the DC voltage gets to the device in reverse polarity, and will not work.

If the wiring is standard straight-through cable, then there should be no issue; and also if the device uses the Mode B standard then the power is sent over other conductors which do not cross over, even if inside a crossover cable.

Of course, the wiring scheme is different.

This are the following schemes for Power Over Ethernet (POE) wiring

I have taken this from Wikipedia link here

Note: Please remember that the maximum voltage allowed is 50V and current is .36A which is 18W. So the load you are connecting to should not be drawing more power than this recommended current / voltage levels.

No; POE does not require any different or special cabling.