We're affected by an electric fence and get a more or less steady 2800 ES/hour. It doesn't affect throughput in any way that I can detect, except that the ISP has to disable DLM to prevent BT clocking the line down to some punitive banded profile. The fence doesn't affect noise margin either, when the fence is off you see errors drop to zero but margin is unchanged.
I've noticed two things, one is that the interference almost disappears when it's raining, secondly that fixing some bad joints in the fence made some initial improvement.