About Us: Established in 1974 to manufacture switching devices for Traffic control needs. PDC has established itself as a leading manufacturer for Load Switches, Flashers, Isolators and Cable Harnesses. PDC has also expanded it's product line to include, Connectors, Locks, Terminal Blocks, Modems and Custom Cable Harnesses to meet all Nema TS-1/TS-2 and 170/2070 specifications.