I investigated a similar but more serious situation where the cable service boxes on the exterior of the houses were actually igniting vinyl and wood siding from heat generated. After determining that all of the houses in question were served by the same pad mounted single phase transformer a little diagramming presented the reason. The transformer lost its center tapped ground. When a large 120 volt load like the burner on a stove was presented to the system, it searched for a ground and found it in the cable TV shield and ground. Apparently many of the service grounds for the houses were high resistance (or at least higher than the cable ground) Some were bonded to water pipes and had no. 6 copper to driven grounds. The cable service had it's own driven ground at the cable terminal at the street. The first clue was that the cable shield to some of the cable services from the cable terminal to the houses was damaged and the cable terminal itself was damaged in addition to the cable service boxes at the houses.