I just moved into this house in January and we noticed the issue the first time we got in the pool. Previous owner said he didn’t use the pool last year at all and come to find out his neighbor said he hadn’t used the pool in the last 3 years. So I’m wondering if that’s coincidence or if he is experienced the problem too and gave up on tryin to fix it. So long story short I have no idea how long this has been going on.That's highly suspect. You might create a trouble ticket with your power utility and let them know that is happening. That could imply that they might have a capacitor bank nearby with a blown fuse. That current imbalance will be carried on the system neutral. Did this problem occur after a recent lightning storm?