Hello!
I found 2 bugs.
Mekanism 1.7.2 7.0.0 build 197 (i think it's the latest version for 1.7.2)

First bug (infinite energy):
If you connect a cable to any Extra Utilities generator, power will not be consumed.

Second bug (infinite cables):
If you place a micropart in the same block with a cable / tube / pipe and break a part you'll get another cable / tube / pipe. That way you can make a lot of free cables / tubes / pipes.

I didn't test it on 1.7.10 and maybe it was already fixed.

Thanks!

Bug #1 sounds like an Extra Utilities issue.
Testing bug #2 now...

Bug #2 has been fixed with 1.7.10 :)

Yeeeaaah I'm not a useless tester :D