The short answer
- First digit (0-6): protection against solid objects and dust, and against people reaching hazardous parts. 5 is dust-protected, 6 is dust-tight.
- Second digit (0-9): protection against water, from dripping (1) through powerful jets (6), immersion (7, 8) and hot high-pressure jets (9).
- Up to 6, a water digit includes the lower ones. 7, 8 and 9 do not: an enclosure for jets and immersion needs a dual code such as IP66/IP67.
- An IP code covers ingress only. It says nothing about corrosion, ice, UV, impact or condensation, so it cannot be converted into a NEMA type.
How to read an IP code
The IP Code is defined in IEC 60529, Degrees of protection provided by enclosures, for electrical equipment rated up to 72.5 kV. It is written as the letters IP, a first characteristic numeral, a second characteristic numeral, and two optional letters:
- First numeral, 0 to 6: protection of people against access to hazardous parts and of the equipment against solid foreign objects, including dust.
- Second numeral, 0 to 9: protection of the equipment against harmful effects from water.
- X: replaces a numeral that is not specified. IPX5 states water protection only; IP2X states solids only.
- Additional letter A, B, C or D (optional): used when protection against access to hazardous parts is higher than the first numeral shows, for example IP20C.
- Supplementary letter H, M, S or W (optional): high-voltage apparatus, tested in motion, tested stationary, or suitable for specified weather conditions.
IEC 60529 also says a degree of protection is to be stated by the numeral, not by its short description. "Waterproof" or "dust-proof" on a datasheet is not an IP code.
First digit: solids and dust
| Digit | Solid objects kept out | People protected against reaching hazardous parts with |
|---|---|---|
| 0 | Not protected | Not protected |
| 1 | 50 mm and larger | The back of a hand |
| 2 | 12.5 mm and larger | A finger (12 mm test finger, 80 mm long) |
| 3 | 2.5 mm and larger | A tool (2.5 mm probe) |
| 4 | 1.0 mm and larger | A wire (1.0 mm probe) |
| 5 | Dust-protected: some dust may enter, but not enough to interfere with operation or impair safety | A wire (1.0 mm probe) |
| 6 | Dust-tight: no ingress of dust | A wire (1.0 mm probe) |
For digits 5 and 6 the enclosure goes into a chamber of circulating talcum powder (2 kg per cubic metre of chamber volume). For a dust-tight rating it is always tested with a slight vacuum inside, pulling up to 80 enclosure volumes of dusty air through it, at no more than 2 kPa, for 2 to 8 hours depending on how fast air can be drawn in. IP6X passes only if no dust deposit is visible inside afterward. IP5X passes if the dust that got in could not interfere with operation or impair safety.
Second digit: water
| Digit | Protected against | Test in brief |
|---|---|---|
| 1 | Vertically dripping water | Drip box, 1 mm/min for 10 min |
| 2 | Dripping water, enclosure tilted up to 15° | Drip box, 3 mm/min, 2.5 min in each of four tilted positions |
| 3 | Spraying water, up to 60° from vertical | Oscillating tube or spray nozzle (10 L/min, 1 min/m², at least 5 min) |
| 4 | Splashing water from any direction | As digit 3, sprayed over ±180° |
| 5 | Water jets | 6.3 mm nozzle, 12.5 L/min, from 2.5–3 m, 1 min/m², at least 3 min |
| 6 | Powerful water jets | 12.5 mm nozzle, 100 L/min, from 2.5–3 m, 1 min/m², at least 3 min |
| 7 | Temporary immersion | 30 min; lowest point 1 m under water (enclosures under 850 mm tall), or top 0.15 m under (taller ones) |
| 8 | Continuous immersion | Conditions agreed between manufacturer and user, more severe than digit 7 |
| 9 | High-pressure, high-temperature water jets | Fan-jet nozzle, 15 L/min, water at 80 °C, 175 ± 25 mm from the surface |
The water tests use fresh water. IEC 60529 warns that protection may not be satisfactory if equipment is cleaned with high-pressure hot water beyond the digit 9 test, or with solvents. And unlike the NEMA hose test, an IP water test does not demand a dry interior: in general, if water does get in, it must not interfere with operation, deposit on insulation where it could cause tracking, reach live parts or windings not designed to run wet, or collect near cable ends.
The common codes, in plain words
| Code | Dust | Water |
|---|---|---|
| IP54 | Dust-protected | Splashing from any direction |
| IP55 | Dust-protected | Water jets (6.3 mm nozzle) |
| IP65 | Dust-tight | Water jets (6.3 mm nozzle) |
| IP66 | Dust-tight | Powerful water jets (12.5 mm nozzle, 100 L/min) |
| IP67 | Dust-tight | Temporary immersion; jets not covered unless dual-coded |
| IP68 | Dust-tight | Continuous immersion at agreed depth and time; jets not covered unless dual-coded |
| IP66/IP67 | Dust-tight | Passed both the powerful-jet and the temporary-immersion tests |
IP68 has no fixed depth or time in IEC 60529, so an IP68 claim is only meaningful with the conditions stated next to it. Ask for them.
Higher is not always better: dual codes
Up to and including 6, a second digit includes every lower one: an IPX6 enclosure also meets IPX5 and IPX4. Digits 7, 8 and 9 break that chain. IEC 60529 states that an enclosure marked only IPX7, IPX8 or IPX9 is considered unsuitable for the conditions it was not tested to, such as water jets, and need not meet them. To claim both, an enclosure carries a multiple code, for example IPX5/IPX7, IP66/IP67 or IPX5/IPX7/IPX9 for "versatile" use.
So a box marked IP67 is not automatically better than one marked IP66 for a washdown area. Immersion pressure and a hose stream load a gasket differently. If the enclosure will be hosed and may also be submerged, specify a dual code.
IPX9 and IP69K
IPX9 was added to IEC 60529 by Amendment 2 in 2013 for high-pressure, high-temperature water jetting at close range. A similar code, IP69K, comes from ISO 20653, the IP code standard for road vehicles. The two come from different standards, so check which one a datasheet means. Hot high-pressure cleaning is covered in more detail in NEMA 4 vs 4X vs IP66 and the washdown enclosure guide.
Converting NEMA types to IP codes (one way only)
NEMA 250 includes a conversion table (Table A-1) showing the IP code each NEMA type meets or exceeds. NEMA marks it plainly: it "cannot be used to convert IEC Classification Designations to NEMA Type Ratings".
| NEMA type | Meets or exceeds |
|---|---|
| 1 | IP20 |
| 2 | IP22 |
| 3R, 3RX | IP24 |
| 3, 3X, 3S, 3SX | IP55 |
| 4, 4X | IP66 |
| 5 | IP53 |
| 6 | IP67 |
| 6P | IP68 |
| 12, 12K, 13 | IP54 |
The reverse fails because NEMA types include tests that IEC 60529 does not: in NEMA's words, the IEC rating "does not require a corrosion test; gasket aging test; dust test or external icing test". NEMA's FAQ adds that NEMA types require the enclosure to be fully installed and ready for use, while IP ratings may apply to partially completed states of installation. In US installations, NEC 110.28 states that IP ratings are not a substitute for enclosure type ratings; check the edition your authority having jurisdiction enforces. The types themselves are explained in NEMA enclosure types, and the most common indoor choice is compared in NEMA 12 vs NEMA 4.
What an IP code does not tell you
IEC 60529 leaves these to the product standard: mechanical impact, corrosion, corrosive solvents such as cutting fluids, fungus, vermin, solar radiation, icing, moisture from condensation and explosive atmospheres. If any of them matter on your site, the IP code alone will not answer the question. Impact has its own code, IK, in IEC 62262; condensation is a design problem covered in enclosure condensation.
An IP code also belongs to a complete system. NEMA's bulletin on conduit puts it simply: the IP rating of an enclosure, its fittings and its conduit is the lowest rating of any part. An IP66 enclosure with an IP54 cable gland is an IP54 assembly. See cutouts, glands and HMI windows for keeping the rating through every opening.
Our ratings. NEMA4 Enclosure wall-mount enclosures in 304 and 316L stainless are manufacturer-rated NEMA 4X-type / IP66 - not UL listed. HMI enclosures have an IP65-type front seal with the display installed, manufacturer rated. Our enclosures carry no IPX7, IPX8, IPX9 or IP69K rating.
Frequently asked questions
What does IP66 mean?
The first 6 means dust-tight: no dust may enter in the IEC 60529 talcum chamber test. The second 6 means protected against powerful water jets: a 12.5 mm nozzle delivering 100 L/min from 2.5 to 3 m, from every direction.
Is IP67 better than IP66?
Not for hosing. IP67 is a temporary immersion test; IEC 60529 treats an enclosure marked only IPX7 as not suitable for water jets. If you need both, look for a dual code such as IP66/IP67.
What does the X in IPX5 or IP5X mean?
X stands in for a digit that is not specified. IPX5 states protection against water jets without stating dust protection; IP5X states dust protection without stating water protection.
What is the difference between IP65 and IP66?
Both are dust-tight. IP65 is tested with a 6.3 mm nozzle at 12.5 L/min; IP66 with a 12.5 mm nozzle at 100 L/min, both from 2.5 to 3 m. An IP66 enclosure also meets IP65.
Can I convert an IP rating to a NEMA type?
No. NEMA's conversion table works only from NEMA type to IP code, because NEMA types add corrosion, icing, gasket and construction requirements that an IP test does not check.
Is IP69K the same as IPX9?
They describe similar high-pressure, high-temperature water tests but come from different standards: IPX9 from IEC 60529 Amendment 2 (2013), IP69K from ISO 20653 for road vehicles. Check which one a datasheet refers to.
Sources
- IEC 60529 Ed. 2.2 (1989 + A1:1999 + A2:2013), Degrees of protection provided by enclosures (IP Code): scope, code arrangement, Tables 1-3 and 8, dust and water tests, dual coding, acceptance conditions
- NEMA, "NEMA Enclosure Types" (Table A-1, conversion of NEMA types to IP codes, and the tests IEC does not require)
- NEMA Technical Services Bulletin No. 123, "NEMA and IP Ratings" (2023): system rating equals the lowest component; Types 4/4X meet IP65 and IP66
- NEMA, "NEMA FAQs: Enclosures" (Q11 installed vs partially installed, Q13 water test pass criteria, Q19 NEC 110.28)
- ISO 20653:2013, Road vehicles, Degrees of protection (IP code)
- BSI, IEC 62262 / EN 62262, the IK code for external mechanical impact