Copy/pasted from MCforums, my own post
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TC works fine, EE works fine, RP2 has a marble spawn issue, BC3 is fine on my end, however I'd like to point out an IC2 issue.
copper wires break (not visually) when traveling back from other worlds. and I noticed where it breaks. if you have a generator - batbox - machine setup it will break at the generator. If you have a solar array - MFU - LVTF - battbox - machine setup it will break at the LVTF.
So I believe it breaks from the connector TO the batbox. I dont know if it is mystcraft that is doing it or going to the nether also breaks the wire. I will post this (copy paste) into the IC2 forums also as it might just be an IC2 bug and nothing to do with mystcraft.
I have not tested this going to the nether and I did not notice this before installing mystcraft..