Zero Surge products do not rely on the ground circuit for effective surge protection, but proper grounding at the service entrance must exist. The grounding inside a home or building is important mainly from a safety aspect.
Most important for surge protection is the grounding at the building’s service entrance. If there is any question about the electrical ground at the service entrance, it is very important that it be checked by a licensed electrician. According to the National Electric Code (NEC), an earth ground reference is required at the building entrance.
Learn more about using Zero Surge products with ungrounded receptacles by watching this video.