Abstract: A modular wiring system including a fixture interceptor for electrically wiring together several overhead light fixtures of an office building using modular components whereby a selected group of fixtures may be locally switched as desired. All components of the system matingly connect with other components through molded connectors and recessed sockets to provide foolproof installation and strong, wear-resistant physical connections. Each fixture is provided with a self-fastening, molded fixture interceptor having recessed input and output fixture sockets. Mating joiner cables connect a power supply to a starting fixture and pairs of successive fixtures, one end of each joiner cable connecting to an input fixture socket of one fixture and the other end to an output fixture socket of another fixture. A molded switching interceptor (i.e. switch tap box) is connected via a joiner cable to the fixture interceptor of the first fixture selected for local switching.