IPX4 or IPX5: Choosing the Right Water Level

IPX4 and IPX5 are adjacent in the code and far apart in severity. Choosing between them is a matter of describing the environment honestly, not of buying margin.

What IPX4 covers

Water splashed from any direction, at low pressure, from an oscillating tube that swings through 180 degrees. It represents rain driven by wind, spillage, and cleaning with a low pressure hose at a distance. It does not represent a directed jet.

What IPX5 adds

A 6.3 mm jet at 12.5 litres per minute from 3 metres, aimed deliberately at the enclosure. It represents a hose used for washing down equipment, and it will find gaps that splash never reaches, particularly on the underside and around cable entries.

Choosing

Outdoor equipment exposed to weather but not to hoses: IPX4 is defensible. Equipment washed with a hose: IPX5. Equipment washed with a pressure washer at close range: IPX6 at minimum, and IPX9K if steam is involved. Over-specifying has a cost in seals and vents; under-specifying produces field failures that are far more expensive.

Related technical notes

• Preconditioning Before an IP Test: The Step Everyone Skips
• IP Rating and NEMA Type: Mapping Two Different Systems
• Why Water Enters from Below: The Underside Problem