Waldo,
Im sure (from many experiences) that when #3 is hashing @ 50% this means is drawning not significantly more than ~50% of power from the wall.
You can verify this with your kill-a-watt, please.
P.S.
And I think at such expensive power you have its right time for selling Terraminer on ebay
8-9 btc maybe per item is definitely better than todays nothing from mining
(no chances for mining these 8-9 btc already

)