I reported this on EU github also, the crash happens if i try to place a energy node from EU in the world. the crash boots me from the world/server and i have to use mcedit to remove the node to get inn again. without railcraft it works.

log: http://pastebin.com/juS6dWQR

Probably a Extra Utilities or Buildcraft issue, Railcraft does not use that API at all. It could be that BC is not properly incrementing its API version, since RC doesn't support or ship the BC-6.x API, only the BC-5.x API.