This paper provides a brief perspective on how the coordination of cascaded surge-protective devices (SPDs) has become an issue. The authors propose an approach where the 'ancient' technology of gapped arresters may well be the answer to the dilemma of the incompatibility of a service-entrance SPD having relatively high limiting voltage with the proliferation of built-in or plug-in SPDs having relatively low limiting voltage inside the buildings. The solution involves providing a gapped arrester at the service entrance and gapless SPDs inside the building. An example is given of such a combination, with experimental verification of the proposed solution and computer modeling that allows a parametric evaluation of the significant factors in any candidate combination of SPDs.
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