UK How IP65 and IP66 differ
IP65 and IP66 are ingress protection ratings defined by IEC 60529. The first digit, 6, is the same in both and means the enclosure is dust tight. The second digit sets the water test: 5 for water jets and 6 for powerful water jets. So the whole difference between IP65 vs IP66 is how hard the water hits.
Both ratings are tested by spraying the enclosure from every practical direction. The IP66 jet carries eight times the flow of the IP65 jet through a nozzle about twice the diameter, so it hits much harder. IP65 is common on panel PC fronts and indoor equipment that sees occasional splashes; IP66 is the usual choice outdoors and in areas cleaned with a hose. For each rating on its own, see our explainer on what IP65 means.
IP65 vs IP66 test conditions
The two water tests use the same method and duration. Only the nozzle and the flow rate change.
| Test detail | IP65 | IP66 |
|---|---|---|
| Dust protection | Dust tight | Dust tight |
| Water test | Water jets | Powerful water jets |
| Nozzle diameter | 6.3 mm | 12.5 mm |
| Flow rate | 12.5 litres per minute | 100 litres per minute |
| Approximate pressure at the nozzle | Around 30 kPa | Around 100 kPa |
| Distance | 2.5 to 3 m | 2.5 to 3 m |
| Duration | 1 minute per square metre, at least 3 minutes | 1 minute per square metre, at least 3 minutes |
| Pass condition | No water that harms operation or safety | No water that harms operation or safety |
The pass condition matters: IEC 60529 allows a little water inside if it does no harm. A rating is a tested outcome, not a promise that no moisture will ever enter, which is why manufacturers also design seals and drainage around the real installation.
What each rating suits
In practice the choice comes down to the water the equipment will meet in service.
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IP65. Covers splashes and low-pressure jets, such as light rain and wipe-down cleaning. Common on the front face of panel PCs and monitors set into a cabinet, and on indoor equipment near wet processes.
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IP66. Covers heavy rain, sea spray and hose-down cleaning. The usual choice for outdoor cabinets, vehicles, docks and food production areas cleaned with a hose.
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Not immersion. Neither rating covers being submerged; that needs IP67 or IP68.
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High pressure. Pressure washers and steam cleaning call for IP69K instead.
Does IP66 include IP65?
Yes. For the water jet levels, IEC 60529 treats the second digits up to 6 as cumulative, so an enclosure that passes the IP66 test is deemed to meet IP65 and the lower levels too. The immersion ratings, IP67 and IP68, are different: they test still water rather than jets, so a product can be IP67 without passing IP66. That is why rugged equipment is often marked with a dual rating such as IP66/IP67.
North American specifications often use NEMA enclosure types instead. NEMA 4 and 4X are broadly comparable to IP66 for water, with 4X adding corrosion resistance, but the tests are not identical, so a conversion is a guide rather than an equivalence. Our comparison of IP66 vs IP67 covers the step to immersion.
Keeping the rating in service
An IP rating describes the enclosure as tested. Whether it holds on site depends on how the equipment is installed and maintained.
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Cable glands and connectors. Every gland, connector and blanking plug must carry at least the same rating, and be tightened to the maker’s torque.
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Gaskets and door seals. Seals age with heat, UV and cleaning chemicals, so check them at service intervals and replace them if they harden or crack.
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Temperature cycling. An enclosure that heats and cools can draw in moist air through tiny gaps. Pressure-equalising vents help, and our guide to preventing condensation on electronics covers the rest.
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Mounting position. Avoid pointing connectors upwards where water can pool around them.
Choosing between IP65 and IP66
The step from IP65 to IP66 matters most outdoors and anywhere a hose is used for cleaning. If the equipment only faces splashes, condensation or a damp cloth, IP65 is usually enough. If it faces driving rain, waves, a hose or a cleaning routine you do not control, specify IP66. Remember that the rating applies to the whole enclosure as installed: cable glands, connectors and any rear face must be sealed to the same level.
Front-sealed panel PCs are a common case. A front IP65 rating protects the face of the screen, while the rear sits in a dry cabinet. For panels exposed on all sides, choose a fully sealed IP66 or higher model. Our IP66 computers are sealed against jets and spray, our front IP65 panel PCs suit cabinet doors and machine panels, and our IP rating chart sets out every level.
Quick answers on IP65 vs IP66
IP65 and IP66: common questions
Is IP66 better than IP65?
For water, yes. Both are dust tight, but IP66 withstands water jets with eight times the flow. It is the safer choice outdoors and where hoses are used.
Is IP66 waterproof?
Against jets and spray, not immersion. IP66 survives powerful water jets from any direction. For submersion, look for IP67 or IP68.
Is IP65 suitable for outdoor use?
Sheltered outdoor use, usually. IP65 copes with rain and splashes, but exposed sites with driving rain, sea spray or hosing are better served by IP66.
Can you hose down an IP65 enclosure?
Gently. IP65 is tested with low-pressure jets. Regular hose-down cleaning calls for IP66, and pressure washing for IP69K.
Does IP66 cover IP65?
Yes. An enclosure that passes the IP66 jet test is deemed to meet IP65 as well, because the jet levels are cumulative.
We supply IP65 and IP66 computers, panel PCs and monitors with the cable glands, connectors and mounting matched to the site as standard, so the installed system keeps the rating it was tested to.