The difference is in how the e3k do surge protection. It is different from the 1k and 2k series.
Are you on a tower with an FM transmitter? If yes you must use shielded cables, you do not need armored. You must use an LPU on the bottom of the tower before going to the building, this is where you bond the cable drain wire to and earth the system to the tower earth. Do not bond your radio to the tower, just mount it normally and make sure you have a lightning spike above your equipment.
Inside the shelter, you may need to add a large torroid ferrite and wrap your ethernet cable through it. Especially if you share the shelter with said transmitter( they dont usually leak RF, they bleed it!).
If you are on a tower that is near an FM site, I have found it useful to ensure my cable is run inside a protected location. The inside of the leg is usually good. This minimizes the amount of injection your cable is exposed to. On bad sites, we have run fiber and power up to a metal box near the radios, a set of media converters and a very short cable to the radio works wonders.