No design engineer or technician wants their design to fail in application, leading to dissatisfied customers and costly field service or returns. Water is the enemy of electronic and electrical components. It can cause corrosion and electrical shorts. Fortunately, the right waterproof enclosure will protect your design and reputation.
If your design will be used in locations subject to factory washdowns, rain, marine humidity, and wet conditions, then an appropriately rated NEMA or IP waterproof enclosure is essential. Understanding how these enclosures are tested for water intrusion can help you make informed decisions about safeguarding your design.
Understanding IP Ratings
Before we dive into the tests, it’s important to explain what IP ratings are. They are a crucial aspect of ensuring the safety and reliability of electrical enclosures in various environments. Defined by the International Electrotechnical Commission (IEC), the IP rating system provides a standardized way to classify the level of protection against solid objects and liquids. This system helps manufacturers and engineers select the right enclosure for specific applications, ensuring that the device can withstand the environmental conditions it will be exposed to. For instance, an IP65 rating indicates that the enclosure is dust tight and protected against low pressure water jets, making it suitable for outdoor equipment and factory washdowns.
The Science Behind Waterproof IP Enclosure Testing
When an engineer specifies a waterproof IP enclosure, they’re not just taking the manufacturer’s word that the enclosure is waterproof. These enclosure designs undergo rigorous testing procedures to earn their ratings. But what exactly happens during IP enclosure tests?
IP (Ingress Protection) ratings consist of two digits: the first indicates protection against solid objects, while the second—ranging from 0 to 8—indicates water protection. For waterproof applications, we’re typically looking at ratings from IP65 through IP68.
IP Enclosure Tests
According to IEC 60529, the international standard that defines IP testing, each level requires increasingly stringent tests:
- IP65 Testing: The enclosure is subjected to water projected by a 6.3 mm nozzle from any direction. The test uses a flow rate of 12.5 liters per minute at a pressure of 30 kPa from a distance of 3 meters for at least 3 minutes. The enclosure must prevent any harmful water ingress.
- IP66 Testing: Similar to IP65 but using a 12.5 mm nozzle with 100 liters per minute at 100 kPa pressure, creating powerful water jets. The test duration is typically 3 minutes, challenging the enclosure’s seals under significant pressure.
- IP67 Testing: The enclosure is fully immersed in water to a depth of 1 meter for 30 minutes. After the test period, the waterproof IP enclosure is removed and inspected for any water penetration that could interfere with proper operation.
- IP68 Testing: This involves continuous immersion under conditions specified by the manufacturer (typically deeper and longer than IP67). The exact test parameters—depth and duration—should be clearly stated by the manufacturer, as this rating can vary significantly between products.
During these IP enclosure tests, technicians place inside the enclosure actual electronics or a test apparatus that can detect water ingress through electrical continuity sensors. Then they place the enclosure in a specialized test chamber that creates precisely controlled water spray patterns and immersion conditions.
NEMA Standards: Comprehensive Protection Testing
While IP ratings are international, NEMA ratings provide a more comprehensive approach to environmental protection, especially in North America. The National Electrical Manufacturers Association defines several waterproof ratings, including NEMA 4X, NEMA 6, and NEMA 6P.
NEMA Enclosure Tests
NEMA testing procedures include:
- NEMA 4X Testing: The enclosure is subjected to a water spray from a 1-inch nozzle delivering 65 gallons per minute from a distance of 10 feet for 5 minutes from each of five directions (excluding the bottom). In addition to this hose-down test, NEMA 4X enclosures must also demonstrate corrosion resistance through salt spray testing—typically 200 hours of exposure to a salt fog atmosphere per ASTM B117 standards.
- NEMA 6 Testing: The waterproof enclosure equivalent is subjected to temporary submersion tests where the enclosure is immersed in water at a depth of 6 feet for 30 minutes. Unlike IP testing, NEMA also requires the enclosure to withstand the formation of ice on the enclosure without damage.
- NEMA 6P Testing: This includes all NEMA 6 requirements plus prolonged submersion testing (typically for 24 hours or more). These enclosures must maintain their integrity during extended periods of time underwater. This makes them suitable for applications in areas prone to flooding.
What makes NEMA testing particularly rigorous is the inclusion of additional environmental factors beyond water ingress. For instance, NEMA ratings also consider external icing, corrosive environments, and (in the cases of NEMA 7 and NEMA 8) explosion resistance—factors not directly addressed by IP ratings alone.
Demonstration of an IP68 waterproof enclosure
While Bud Industries does not have the equipment to do laboratory testing, we made a video of an IP68 / NEMA 6P enclosure being submerged in one meter of water for more than 30 minutes. This demonstration shows the effectiveness of a properly rated waterproof enclosure.
How Businesses Ensure Reliability in Extreme Conditions
Selecting the appropriately rated enclosure is just the first step. To be sure of continued protection in extreme conditions, businesses should implement several practices:
- Consider the entire environment: Some gasket materials can deteriorate when exposed to certain industrial chemicals or extreme temperatures, and some plastics used in enclosure construction can degrade in sunlight. Beyond water, think about temperature fluctuations, UV exposure, and chemical exposure that might compromise seals over time.
- Implement regular maintenance: Even the best enclosures require inspection of gaskets and seals, particularly in harsh environments. Advise customers to establish a preventative maintenance schedule based on the severity of conditions. In especially challenging environments, quarterly inspections may be necessary. Tip: an enclosure with a clear plastic cover will allow inspection without opening the enclosure under field conditions.
- Proper installation matters: Even the most robust enclosure will fail if cable glands and access points aren’t properly sealed during installation. Follow manufacturer guidelines for torque specifications on enclosure fasteners. Use cable glands for cable entries and use gaskets around openings for switches, indicator lights, and displays. Remember that the protection rating applies to the enclosure only before it is modified with holes and cutouts.
- Verify compliance documentation: Request test reports from manufacturers that detail the specific test parameters used to achieve the claimed ratings. Reputable manufacturers like Bud Industries provide this documentation to verify their waterproof IP enclosure products meet or exceed the stated protection levels.
- Consider third-party verification: For critical applications, some businesses opt for additional verification testing beyond manufacturer claims. Independent laboratories can validate that an enclosure meets specific requirements for your particular application scenario.
When properly selected and maintained, a waterproof enclosure provides peace of mind that your sensitive electronics and electrical components are protected, whether they’re facing a routine factory washdown or unusual weather challenges. By understanding the testing behind these ratings, engineers can make informed decisions that ensure the reliable performance of their designs for their entire service life.
