How much power are you getting out of the turbines? If you have 3 IV dynamo hatches you aren't necessarily sending an amp from each dynamo hatch every tick. There's some randomness there and you may or may not ever have a tick where all three output an amp at the same time. I would wire it such that two of them are on a 2x cable and the third is on a separate 1x or you combine it and go to 4x.
Turns out it ended up burning the wire enventually (atleast...sporadically.) I came to edit my message but you already replyed :p