Bench Talk

Fleets of cars, buses, and trucks are often on the job all day and night, working in rugged environments where electronics are at the mercy of the weather, road conditions, and cleaning processes. Dust and water are sworn enemies of electronics, and particularly in commercial vehicle fleets, where the number of vehicles, high use, and rugged environments only compound the need to protect electronic components.

The Ingress Protection (IP) rating system (not to be confused with the highly recognized Internet Protocol) is a system of designating wet and dry contamination resistance in electronic enclosures. Established in the International Electrotechnical Commission’s (IEC) 60529 standard, the system measures an electrical enclosure’s ingress protection against solid and liquid contaminants and has become increasingly needed as the use of electronics in commercial fleets increases.

The system designates protection using a two-digit IP Code, as in IP67:

• The first digit—0 through 6—indicates the enclosure’s protection against dust and solid objects.
• The second digit—0 through 9—indicates the enclosure’s protection against liquids.

The higher the number, the higher the level of protection: 

An IP rating, then, combines the solid and liquid rating digits, as in:

• IP67—Dust-tight, protected from temporary submersion in water
• IP68—Dust-tight, protected from continuous submersion in water

We can illustrate the range of liquid IP values using a typical car as an analogy to an enclosure. The car protects the interior during a rainstorm (IP_3). If the wind picks up or if a passing car hits a puddle, IP_4 protection would be needed. Washing the car with a hose would require IP_5 protection. Finally, a commercial car wash with increased water pressure would require an IP_6 rating to keep the interior dry and electronics protected.

Whereas ratings specific to solids relate to size, ratings for liquids present additional variables relevant to commercial vehicle fleets. For example, electronic enclosures’ exposure to close-range, high-pressure, high-temperature water is often a factor, such as during wash-downs as part of periodic maintenance. In 1993, the IEC added the IP_9 rating to address close-range, high-pressure protection from liquids and added the “K” option high-temperature protection of up to 176°F/80°C.

As a result, with the highest rating—IP69K—electronic components can now be both dust-tight (IP 6_) and protected against close-range, high-pressure, high-temperature ingress of liquids (IP_9K). Initially, this rating was used for road vehicles needing regular intensive cleaning, such as dump trucks and cement mixers, but has expanded to include other commercial vehicles as well. The constant-pressure environments that these enclosures see make proper design, including redundant sealing systems, necessary to maximize usable life of the equipment. The HSAutoLink™ II Interconnect System from Molex is available with an IP69K rated option that still enables data rates up to 5Gbps to meet the increasing bandwidth requirements of advanced telematics and camera devices.

Mouser and Molex offer an entire suite of products meant to handle the abuse of harsh environments while providing the performance required for modern commercial fleets. Ruggedized and sealed enclosures must protect electronic circuitry from exposure to liquids, particles, and tampering. Visit mouser.com to see the full line of Molex products designed for harsh environments and automotive fleets.

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