Had a tenant recently vacate, noticed there was some work done on the electrical not sure why when or by whom? Now when a floor heater is turned on lights get dim, when the disposer is turned on lights dim, tv turns off, and when the washing machine is running lights get dim and then real bright, are all these signs of an open neutral?, if so the disposer and washing machine are on their own circuits, they still affects all the lights on 4 separate runs. could that mean the problem is in the service entrance breaker box?