Buildcraft version:
Forge version: 1.12 14.23.0.2552
Link to crash report or log (on pastebin or gist, please don't put the entire log here) : none
Singleplayer/multiplayer: Pipes cannot transfer energy with either RF or MJs as they don't even connect to the engines from BC or RF/FE machines

Additional information:

Thanks for the report! This is a duplicate of #3760

Also engines only connect to power input pipes such as a Wooden kinesis pipe

ah thank you Luigi.