An Overview of IP Ratings and Waterproof Connectors

By Ryan Smoot, Technical Support Engineer, CUI Devices

With the continued rise of portable and wearable electronics, there’s never been a greater need for everyday devices to tolerate exposure to dust and moisture. End-users expect products to survive a plunge into dirt or an accidental drop into water. Ruggedized performance is also essential in other IoT applications, particularly those intended for outdoor use or industrial environments. However, achieving this level of protection against moisture, dust, and other particulates needs to be addressed at the component level—and designed in early on—so as to not compromise reliability.

Connectors, a common component found in virtually every application, represent a potential entry point for these hazards to negatively impact the operation of an overall system. While IP rated connectors, components, and applications are growing in popularity and understanding, what are the various IP rating classifications and what design considerations need to be examined when selecting an IP rated connector?

IP ratings – the basics

Ingress Protection (IP) ratings are defined in the IEC 60529 standard using a standardized scale where the IP prefix is followed by two numbers: the first number representing protection against solids and the second number representing protection against liquids. There are also national or regional equivalents of the standard such as ANSI 60529 (United States) and EN 60529 (Europe).

Image of IP rating code structureFigure 1: IP rating code structure (Image source: CUI Devices)

The numbers in the IP rating code are further defined in the table below (Figure 2). For instance, an IP56 rating means that the part is dust protected, while offering protection against powerful water jets.

Image of IP rating classificationsFigure 2: IP rating classifications (Image source: CUI Devices)

IP rated connector selection

Exposed external connectors are a common entry point for water and dust to enter a device. Determining an application’s intended use at an early stage is vitally important, so that exposed connectors are selected with an IP rating that will meet a system’s minimum requirements.

The most prevalent need for IP rated connectors can be found on a device with external ports such as an audio, USB, or DC power jack. A proper IP rating in this case will protect any internal circuitry from unforeseen water or dust ingress when no plug or external equipment is connected. In other instances, such as industrial cable-to-cable connections, a connector and plug combination that are fully-sealed when mated may be required. This fully-sealed connection can prevent dust and moisture from disrupting signals or damaging components exposed to high-pressure water or even full immersion when in operation.

Diagram of plug and connector cable with locking and sealing interfaceFigure 3: Plug and connector cable with locking and sealing interface (Image source: CUI Devices)

However, it is important to clarify that plugs and connectors with individual IP ratings do not automatically create an IP rated connection. Unless a design integrates an additional sealing mechanism like the screw terminal interface in Figure 3, they are still susceptible to dust and moisture ingress at the connection interface (Figure 4). If the interface was not properly sealed, it could disrupt signals or cause damage to internal circuitry.

Diagram of typical connection susceptible to dust and moistureFigure 4: A typical connection is still susceptible to dust and moisture (Image source: CUI Devices)


As portable devices grow in popularity, so does the need for more rugged components. CUI Devices offers a range of IP67 rated connectors including USB receptacles, 3.5 mm audio jacks, and DC power jacks to give designers additional flexibility in rugged applications. Implementing a custom-shaped gasket or O-ring to provide effective sealing, these connectors achieve dust tight protection and full immersion up to 1 meter in an unconnected state.

Image of CUI Devices’ UJ31-CH-3-MSMT-TR-67 USB connector and PJ-001AH-67 DC power jackFigure 5: CUI Devices’ UJ31-CH-3-MSMT-TR-67 USB connector and PJ-001AH-67 DC power jack (Image source: CUI Devices)

Disclaimer: The opinions, beliefs, and viewpoints expressed by the various authors and/or forum participants on this website do not necessarily reflect the opinions, beliefs, and viewpoints of Digi-Key Electronics or official policies of Digi-Key Electronics.

About this author

Ryan Smoot, Technical Support Engineer, CUI Devices

With an extensive knowledge of CUI Devices' products, Ryan Smoot provides customers with a wide range of technical and application support capabilities in the field. His management of CUI Devices' robust CAD model library further offers engineers with an invaluable resource for streamlining their product designs.