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What is polarization, keying and color coding for interconnect?

Added to IoTplaybook or last updated on: 08/12/2022
What is polarization, keying and color coding for interconnect?

Establishing a properly aligned connection quickly is key in any assembly or installation process. Polarization, keying and color coding are primary means to ensuring connections are made quickly and safely.  In this article we’ll discuss each of these means and the advantages of them.

What is Keying?

Many connectors are designed with a means of being “keyed”, but what does this really mean and what is it designed for? Keying is an important feature because it prevents mis-mating. Incorrect mating could result in mechanical damage, lost signals, or even a short circuit, resulting in loss.  Resulting in lost time for troubleshooting and possibly damaged equipment. Connector keying is the primary means of combating these situations by ensuring the connectors can only be mated in one direction. Keying takes different forms, such as a rectangular connector with a blanking pin in one position or a circular connector with a notch to ensure proper alignment of all pins, such as the Molex BradPower D-Size connectors.


Polarization preventss mis-mating by allowing only one orientation to connect, which is especially important when the operator is unable to see the connector parts while uniting them, or “blind mating”. The Molex polarized Saber Power connector ensures the proper orientation is easily achieved. The image below illustrates how the shape of each position of the receptacle ensures proper polarization.

Color Coding

In a situation where there are several connectors that look similar, color coding helps the operator identify the proper connections quickly, saving time in the assembly or installation process. Examples can be seen in common connectors such as the audio video RCA cables where red, white and yellow indicate right and left channel audio and video, or the Molex CP Wire to Board connectors where each color is for a specific signal or voltage.


All three of these concepts are relatively simple, but provide a crucial means of safety, speed and structure in assembly and installation.  While polarization and keying are commonly confused, you can see how each serves a specific purpose.  Keying can add bulk to a connector but provides a physical attribute, polarization ensures each contact is connected with the proper mate and color coding provides a quick visual indication for proper connection without adding bulk.

Jamie Pederson, Technical Content Manager




This content is provided by our content partner Avnet, a global technology solutions provider with end-to-end ecosystem capabilities. Visit them online for more great content like this.

This article was originally published at Avnet. It was added to IoTplaybook or last modified on 08/12/2022.