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Ingress Protection: Where and Why It Matters

Electronics are like a grumpy neighbor: Neither can tolerate wet and dirty contaminants (kids) in their enclosures (yards). The International Electrotechnical Commission (IEC) has developed a set of Ingress Protection (IP) ratings that serves as a unified system of designating electronic enclosure wet and dry contamination resistance. This article discusses why electronics are particularly averse to contaminants and how contaminants enter electronic enclosures, as well as discusses IP ratings and examples.

Why Electronics are Contaminant-Averse

Any contaminants entering an electronic enclosure or case can cause damage ranging from shortened usable life to ultimately rendering the equipment useless. Dust and dirt entering an electronic enclosure can do harm in any one of many ways. Dust is capable of accumulating inside the sockets, ports, and crevices of electronics and circuits. If dust builds up excessively, bad things can happen: The dust may build up to form an insulating layer that causes the circuits to overheat. If the dust or dirt inserts itself between contacting surfaces, poor conductance may occur creating problems for switches, relays, and connectors. In higher voltage applications, the dust and dirt may facilitate arcing between line voltage and ground.

Wetness, aka water, moisture, and humidity are sworn enemies of electronics, especially with delicate microcircuits. Rugged environments are where the product is at the mercy of the weather, be it heavy thunderstorms or light drizzle. Cleaning equipment with simple flowing water can create problems let alone a high pressure stream (self-service car washes are an example of electronic enclosure abuse every time someone chooses to clean under the hood). Even humid environments can form problematic condensation on internal components. A device moved from a cold environment to one that is warm and humid may see the formation of moisture on circuitry. If the power is applied before this condensation can evaporate, short circuits can cause failure.

Exposure to harsh chemicals, surfactants, or cleaning liquids such as those used in high-pressure spray cleaning equipment can have a corrosive, damaging effect on electronics and circuitry. Copper, aluminum, and silver compounds are particularly susceptible. Corrosion deteriorates the base metal resulting in diminished current carrying capacity. The ever-shrinking size of electronic components means there is less conductive mass to deteriorate and, therefore, increases the vulnerability of failure.

IEC IP Rating System Overview

Not to be confused with the highly recognized Internet Protocol, the IEC IP standard measures ingress protection and has become increasingly popular as consumer electronic devices become more mobile with a focus on ruggedness. The IP designation (or code) is a two-digit number, as in IP67, IP68, and IP69K:

• The first digit of the IP Code indicates the device's protection level against solid objects.
• The second digit shows how well liquids are kept from the electronic components and circuitry within the enclosure.

As Table 1 shows, solid and liquid protection levels increase with higher designated ratings.

Table 1: In IEC IP ratings, solid and liquid protection levels increase with higher designated ratings.

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

• IP67 —Dust tight, protected from temporary submersion in water
• IP68 —Dust tight, protected from continuous submersion in water
• IP69K —Dust tight, protected from water during high pressure/steam cleaning (but not submersible)

"Solid objects" include a full spectrum from objects larger than 50mm to minuscule specks of dust. An IP2_ rating indicates that the enclosure will keep out children's fingers or similar objects; anything smaller than a finger may get through and do damage. An IP rating of IP6_ designates the device is dust-tight.

The second digit indicates an enclosure's protection level against liquids. This designation ranges from 0 to 9K. A rating of 3 means the device is protected from rain while a rating of 8 shows the case can be submerged for long periods. A liquid IP designation of _9K indicates the device has the highest rating indicating it is protected against water during high pressure/steam cleaning. The caveat is that a _9K rating does not necessarily mean the enclosure can be submerged (IP_8).

IEC IP Ratings Applied

For those of us who have removed a cover from an electronic enclosure, whether a computer or an automotive fuse box, dust seems to find a way in. While low IP solids ratings are focused on keeping the outside world-mainly your fingers and other probing objects-out of the device, the 5 and 6 designations focus on the ingress of dust into the enclosure. A rating of 5 states dust will not interfere with device operation, while a 6 indicates no dust or dirt will be present. Desktop computers operate at a level 5 to balance cooling, cost, and circuit protection requirements. Sensitive sensors and circuitry often encase or "pot" electronics to prevent any solids contact and meet an IP6_.

Water can strike an enclosure in many ways. Gravity provides the motive force for vertical impingement often referred to as rain and dripping. Equipment used outdoors and termed weatherproof generally align here. Protected receptacles, security cameras, and outdoor lighting are good examples. When a motive force is added to rain and dripping we have splashing and spraying. Motive force can occur naturally as in wind or artificially in an industrial setting like the spray created by coolant in a machine tool. Finally, when a liquid is pushed through a nozzle, jets are created. Jets are often used as cleaning applications around the home or in industrial settings.

We can illustrate the range of liquid IP values using the neighbor's car as an analogy to an enclosure. The car protects the interior during a rainstorm (IP_3). If the wind picks up or a passing car hits a puddle (let's hope his window is up) that is an IP_4. When he washes his car in his driveway with a hose, that's an IP_5. Finally, going to a commercial car wash will require an IP_6 rating to keep the interior dry and the vehicle electronics protected.

Immersion is a focal point of ingress protection product rating and qualification. Personal electronic immersion protection was first provided by wristwatches, then cameras, and most recently cell phones. Here the terms waterproof and water resistant are widely open to interpretation, but IP67 and IP68 generally bring some clarity. Immersion-proof electronics are found throughout industry from sensors located within the fluid stream of a processing facility to communication, sensing and navigation equipment that spend part or all of their lives submerged in physical bodies of water. The constant-pressure environments that these enclosures see make proper design, including redundant sealing systems, necessary to maximize usable life of the equipment.

High pressure, high temperature wash-down is used throughout industry. Often, the purpose is to clean microbes and contaminants from equipment that processes food and pharma. Heavy duty cleaning is required to prepare machinery for shipment or as part of periodic maintenance. Don't forget the neighbor who takes a chance at high-temperature pressure washing his engine compartment (hopefully he won't get even grumpier). Industries where you will find IP69K rating requirements include food processing, pharmaceutical, petrochemical, waste treatment, bottling, and transportation.

Mouser Electronics: Harsh Environment Offerings

Mouser offers an entire suite of products meant to handle the abuse of harsh environments. Ruggedized and sealed enclosures must protect electronic circuitry from exposure to liquids, particles, and tampering. Ingress Protection (IP) code (IEC 60529) as well as National Electrical Manufacturers Association (NEMA) ratings are provided in product data.

To find harsh environment products, use a keyword search (including part numbers) to search the entire catalog. Alternatively, you can browse by categories or manufacturers. If you're a registered user, you can use the note-taking function to aggregate and compile your findings.

Mouser also has a very rich and informative harsh environments reference section that provides a wealth of information to assist in specifying and selecting liquid-tight and dust-tight electronic equipment. Here, you'll find several thousand electrical enclosures, boxes, cases, racks, and cabinets listed with corresponding IP values.

The function of the IP code is to provide you with standardized information about your device's capacity to ward off dust, dirt, and liquids. Hopefully, it will accurately advise you whether or not your son's iPhone will take a blast from that grumpy neighbor's water hose.

Steve Schriber, PE is a BSME graduate of Rensselaer Polytechnic Institute. Steve developed a solid manufacturing foundation working in mechanical and electrical power transmission, machine tool, and precision instrument industries. He also ran an engineering consulting company specializing in New York State chemical bulk storage regulations. This rich experience was a perfect match for a newly formed internet startup whose mission is to provide a robust search and discovery experience for engineers and technical buyers. Here he served in several IC and leadership roles including prime responsibility for service providers and contract manufacturers. This internet search engine and content experience provided a broad span of knowledge regarding many products and services across industries. Leveraging these strengths, Steve has provided consulting and technical services in the fields of energy management, manufacturing support, technical writing and content generation.

In addition to his bachelor's degree, Steve has an MBA from the State University of New York at Albany. He is a New York State registered Professional Engineer, an IEP certified Energy Manager, and was certified as a CPM by in the Institute for Supply Management. He is a member of the board of directors for the Delta Chapter of Theta Chi at RPI, a Special Olympics of New York coach and maintains a cross country ski area for the Town of Greenfield, NY.