As how you are describing your base configuration,
it might be the case that at least one of your turrets hit the zombies on their way to you at your horde base, when they are in the vicinity of the "electric support pillars" or under your main base.
So then they beat a little "frustrated" at those before moving in your direction again.
So in the end it is some "rage mode" initiated stuff going on there, just - as Ramethzer0 already suggested - coincidentally looking like intended behaviour towards electrics.
Maybe rework the line of sight of these turrets and it might stop happening.