Executive Summary: The Ingress Protection Hierarchy
IP Ratings (Ingress Protection) define a connector's sealing effectiveness against solids (first digit) and liquids (second digit) per IEC 60529.
- IP67: Dust-tight and protected against temporary immersion (1 meter for 30 minutes).
- IP68: Dust-tight and protected against continuous submersion (depth/time defined by manufacturer, typically >1 meter).
- IP69K: Dust-tight and protected against high-pressure, high-temperature steam jets (DIN 40050-9).
Key Engineering Rules of Thumb:
- The "Mated" Rule: Most connectors are only IP-rated when MATED. An unmated IP67 connector left open on a deck will corrode. Always specify dust caps for unmated ports.
- The "Subset" Fallacy: IP69K is NOT better than IP68; it is different. IP68 is for underwater pressure; IP69K is for surface spraying. A device can be IP68 but fail IP69K tests (and vice versa).
- Cable Jacket Bonding: An IP67 connector does not make an IP67 assembly if the cable jacket doesn't bond to the boot. Material compatibility (Overmolding) is required.
Technical Deep Dive: Defining the Boundaries of Waterproofing
Specifying the wrong IP rating is the leading cause of corrosion-related electrical failure in outdoor and industrial environments. It is critical to understand the test conditions behind the code.
1. IP67: Temporary Immersion (The Industry Standard)
The "6" indicates total protection against dust. The "7" indicates protection against temporary immersion.
- Test Condition: The lowest point of the enclosure is 1000mm (1m) below the surface of the water. Duration is 30 minutes.
- Real-World Application: Ideal for outdoor equipment that may be rained on or dropped in a puddle but retrieved quickly. It is NOT designed for permanent underwater installation or high-pressure cleaning.
- Common Connectors: M12, standard USB Type-C (Industrial), Push-Pull circulars.
- 2. IP68: Continuous Submersion (The Deep Water Spec)
The "8" indicates continuous submersion beyond 1 meter.
- The Manufacturer Variable: Unlike IP67, the specific depth and duration for IP68 are agreed upon by manufacturer and user. It must be more severe than IP67.
- Typical Spec: Often defined as 2 meters for 24 hours, or 10 meters for 1 hour. You MUST check the datasheet. "IP68" on a label does not automatically mean "infinite depth."
- Real-World Application: Sump pumps, underwater lighting, marine hull sensors.
3. IP69K: High-Pressure Washdown (The Sanitary Spec)
Originally a German DIN standard (now part of ISO 20653), the "9K" tests for steam cleaning.
- Test Condition: Water jet sprayed at 80°C (176°F) at pressures of 80–100 bar (1160–1450 PSI) at close range (10-15cm).
- Mechanical Stress: This is not just a water test; it is a mechanical stress test. The force of the jet can shear poorly designed seals or peel away labels.
- Real-World Application: Food & Beverage processing (sanitization), pharmaceutical manufacturing, dump trucks, and cement mixers requiring daily pressure washing.
Comparison Data: Sealing Capabilities Matrix
|
Rating |
Dust Protection (1st Digit) |
Liquid Protection (2nd Digit) |
Test Definition |
Typical Application |
|---|---|---|---|---|
|
IP67 |
6 (Dust Tight) |
7 (Immersion) |
1m depth for 30 mins |
Outdoor sensors, heavy equipment, cellular radios |
|
IP68 |
6 (Dust Tight) |
8 (Submersion) |
Mfr Defined (>1m, continuous) |
Underwater vehicles (ROVs), marine pumps |
|
IP69K |
6 (Dust Tight) |
9K (Steam Jet) |
High Press/Temp Washdown |
Food processing, washdown bays, medical |
Frequently Asked Questions (FAQ)
Is IP68 better than IP69K?
No, they are different scales. IP68 tests for static pressure (deep water). IP69K tests for dynamic force and thermal shock (high-pressure steam). A connector designed for deep sea (IP68) might have soft seals that would be blasted apart by a steam jet (IP69K). Conversely, a rigid IP69K connector might leak under deep-water pressure. Many industrial connectors carry dual ratings (IP68/IP69K) to cover both scenarios.
Does an IP rating cover the whole cable assembly?
Only if the assembly is manufactured correctly. An IP67 connector crimped onto a cable without a proper seal at the backshell (entry point) allows water to wick down the wire strands ("capillary action"), bypassing the connector seal entirely. Overmolding or heat-shrink sealing at the cable entry is required to extend the IP rating to the full harness.
What does "Mated Only" mean?
Most connector IP ratings apply only when the plug is fully mated to the receptacle. When unmated, the contact pins are exposed to air, humidity, and dust. If a cable is left unplugged in the rain, water will enter the connector body. Once mated again, that trapped water causes corrosion. For unmated protection, you must specify Sealing Caps or Dust Covers.
Can I wash IP67 connectors with a pressure washer?
Generally, no. IP67 is rated for static immersion, not high-velocity jets. The pressure from a standard power washer can force water past seals designed only for 1 meter of static head pressure. For equipment that will be pressure washed, specify IP65 (water jets) or IP69K (high-temp/pressure jets).
About the Author
Michael Wang
Senior Technical Engineer
As the technical lead at TeleWire, Michael bridges the critical gap between complex engineering requirements and precision manufacturing. With deep expertise in Design for Manufacturing (DFM) and signal integrity, he oversees the technical validation of custom interconnect solutions for mission-critical automotive, industrial, and medical applications.
