From The Free dictionary by Farlex, a receptacle is defined as “A fitting connected to a power supply and equipped to receive a plug.” I like this definition it describes both halves of the receptacle. In the automotive industry, the back half of a receptacle has threading on the nut with leads that could possibly connect a power supply. The front half describes which kind of cordset is needed. Typically, receptacles are used in a control cabinet, where there is easy access and out of the movement of machinery. Inside a control cabinet is a power source and/or programmable logic controller (PLC) which a receptacle would be wired to in the configuration of the controller. Receptacles used on a control box normally have a tight seal to keep out moisture and dust.
When looking at a receptacle there are two ends with different kinds of threading. In the front of the receptacle has a connection for a cable to connect to the outside environment, cells, and machinery, to the control box. The different cables could have diameter widths of M8, M12, 7/8”, 1” and more. From the picture, we see the front side of the receptacle calls for the M12x1 which would use a M12 cable. The first number is always the diameter of the outer threads. The other end of the receptacle, ½”-14NPT, where the leads come out, has another diameter referred as to the mounting type. There are many different kinds of mounting: Metric, PG, NPT, front mount, back mount, panel mount, etc. The two mounts types being explained here are Metric and NPT.