When a project calls for a waterproof connector, shell size is an important decision but it should not be made in isolation. M16, M20 and M25 connector families can support different contact arrangements and cable layouts. The useful choice is the one that fits the required circuits, electrical needs, installation space and service process of the finished equipment.
Start with circuits and electrical requirements
Define the number and type of circuits first. The CONNIXTECH self-locking catalogue includes M16 configurations from 2PIN through 8PIN, including a 2+4PIN mixed-contact arrangement. M20 entries include configurations from 2PIN through 16PIN, including a 3+9PIN mixed-contact arrangement. M25 entries include 2PIN and 3PIN options with catalogue-listed 32A and 40A configurations. These examples show why required circuits and current should guide the selection before shell size is chosen.
Evaluate the physical installation
Shell size affects the space needed at the mounting point, the cable exit and the surrounding enclosure. Review panel area, connector spacing, cable diameter, bend allowance and access for assembly or maintenance. A larger connector may support a different arrangement, but it must still fit the equipment layout without creating routing or service difficulties.
Consider power-only and mixed-contact needs
Some systems require a straightforward power interface, while others need power alongside control or monitoring circuits. A mixed-contact arrangement can simplify the number of connection points when power and auxiliary signals must cross the same interface. Map every required circuit before comparing M16, M20 and M25 options.
Choose the connection style with the size
CONNIXTECH lists threaded M12, M16, M20 and M25 families as well as self-locking M16, M20 and M25 families. Size and locking method should be reviewed together, based on mating frequency, available handling space, cable routing and the required assembly process. The appropriate combination depends on the complete application, not a single size label.
Request a configuration review
For a focused recommendation, share your circuit list, current and voltage requirements, preferred connection method, panel arrangement, cable details and operating environment. Browse available families in the Product Centre or request a quote to discuss the most suitable waterproof connector size for your project.