A semiconductor network is interposed between first and second multiple-port interfaces each having high-voltage, intermediate-voltage and ground ports to form a switch assembly. The assembly includes a primary switch circuit, a support network, internal and external-port circuits and internal and external-port control circuits. The primary switch circuit is coupled to high-voltage ports of the multiple-port interfaces and to the support network. The internal and external-port circuits are coupled to intermediate-voltage ports of the multiple-port interfaces, the internal and external-port control circuits and the support network. The internal-port control circuit is coupled to the internal-port circuit, the support network and a ground port of a first multiple-port interface. The external-port control circuit is coupled to the external-port circuit, the support network and a ground port of the second multiple-port interface. The assembly has a low-leakage current in both open and closed states when exposed to a range of high voltages.