"A ground loop is the result of careless or inappropriate design or interconnection of electrical equipment that results in there being multiple paths to ground

"A ground loop is the result of careless or inappropriate design or interconnection of electrical equipment that results in there being multiple paths to ground where this is not required, so a complete loop is formed.": https://en.m.wikipedia.org/wiki/Ground_loop_(electricity) https://en.m.wikipedia.org/wiki/Ground_loop_(electricity)