Connectors and cable assemblies are the plugs, wires and cut-to-length cable sets that join every machine, car and server rack. A connector is the plug and socket that join two wires or devices. A cable assembly is a set of wires cut to length, with connectors fitted at the ends, and made for one product.
Connectors are chosen very early in the design of a product, and then supplied for its whole life. An engineer who designs a product picks a connector from one maker, tests it, and writes it into the design. Changing it later means testing the product again. This is a design win: once the maker's part is in the design, the maker supplies it for as long as the product is made.
The engineer's choice depends on several things. The connector must carry the right current without heating. It must hold its grip under vibration, as in a vehicle or a machine. It must resist dust and water, which is shown by its IP rating. And it must work across the temperatures that the product will meet. A wiring harness is mostly assembled by hand, because the wires are of different lengths and take different routes, so cable assembly is labour-intensive work.
Take, for example, a new scooter model that an Indian maker plans to build for eight years. The design team selects the connector for the headlight, the battery and the controller in the first year. The connector maker then supplies those connectors for all eight years, and for spare parts after that. A cable maker cuts and joins the wires into one harness, which is a bundle of wires that runs through the vehicle. The way the wires are laid out is the vehicle's E/E architecture.
Connectors are also used in factories to join sensors to controllers, in telecom networks with optical fibre cable, and in the racks of AI cluster networking, where very fast cables join thousands of chips. Special materials, from advanced materials makers, are used for insulation that must resist heat or oil.
The boxes that protect connections from dust and water are electrical enclosures.