Well looks like I'm kind slow to understand things
It is a bug in the refinery (and the energy routing), I have reported it. Also I was in error when I said that, the refinery itself uses up to that amount of energy, the actual recipe has a different value. As such, the large electric engine has enough power to run 2.5 refineries at full speed.
I do not know how this bug effects the actual output of if it is just visual, I have not done extensive testing on that fact.
As stated by silentdeth, he already reported it. But i was confused at what visual bug he meant, so i tested it out.
I mentioned it to Silentdeth a couple months ago during 1.8.1 when I first discovered it was doing that in my refinery - but I don't think SpaceToad is aware of it.
I wasn't sure if it was an issue unique to this mod or whether "normal" BuildCraft engines behaved the same way. Perhaps you could do a side-by-side test with one combustion engine directly applied to a refinery, and another supplying power by pipe? If there's still a difference, then SpaceToad would surely like to hear of it - if not, then Silentdeth will benefit from the report.
Wow, what a difference! That's how the large electric engine should behave - it's supposed to be as powerful as 5 combustion engines, if I recall.
That bug should be top priority for spacetoad, because you see many people on youtube who just connect engines directly to quarrys or mining wells. At least that is where i learned from. Or maybe that was a unintended feature, i guess only spacetoad can tell that.