An IP code is "IP" followed by two digits: the first (0–6) rates protection against solid objects and against fingers or tools reaching live or moving parts, the second (0–9) rates protection against water. IP65 is dust-tight and resists 12.5 L/min water jets; IP67 is dust-tight and survives 30 minutes with its lowest point 1 m under fresh water; IP68 survives continuous immersion on terms the maker states, which must be harsher than IP67; IPX9 resists 80 °C high-pressure jets. An X means that digit was not tested. The system is defined by IEC 60529 for electrical enclosures up to 72.5 kV. Sealed IP65–IP68 enclosures cannot use vents, so check the internal temperature with the Heatsink Calculator.
First digit: solid objects and access to hazardous parts
| First digit | Solid objects kept out (object probe) | Access to hazardous parts prevented with |
|---|---|---|
| 0 | Not protected | Not protected |
| 1 | 50 mm diameter sphere and larger | Back of a hand (50 mm sphere) |
| 2 | 12.5 mm diameter sphere and larger | Finger (jointed test finger, 12 mm × 80 mm) |
| 3 | 2.5 mm diameter and larger | Tool (2.5 mm probe) |
| 4 | 1.0 mm diameter and larger | Wire (1.0 mm probe) |
| 5 | Dust-protected: some dust may enter, but not enough to interfere with operation or safety | Wire (1.0 mm probe) |
| 6 | Dust-tight: no ingress of dust | Wire (1.0 mm probe) |
Second digit: water
| Second digit | Protected against | Test (IEC 60529, clause 14.2) |
|---|---|---|
| 0 | Not protected | None |
| 1 | Vertically falling drops | Drip box, 1 mm/min, 10 min on a turntable |
| 2 | Drops with the enclosure tilted up to 15° | Drip box, 3 mm/min, 2.5 min in each of 4 tilted positions |
| 3 | Spraying water up to 60° from vertical | Oscillating tube or spray nozzle (10 L/min), at least 5 min |
| 4 | Splashing water from any direction | As 3, but sprayed from all directions |
| 5 | Water jets | 6.3 mm nozzle, 12.5 L/min, 2.5–3 m away, 1 min/m², at least 3 min |
| 6 | Powerful water jets | 12.5 mm nozzle, 100 L/min, 2.5–3 m away, 1 min/m², at least 3 min |
| 7 | Temporary immersion | 30 min; lowest point 1 m deep (enclosures under 850 mm tall) or top 0.15 m deep |
| 8 | Continuous immersion | Agreed between maker and user; must be more severe than 7 |
| 9 | High-pressure, high-temperature water jets | 80 °C water, fan jet 15 L/min, 30 s per angle or 1 min/m² (added 2013) |
What the water tests actually involve
- Fresh water, matched temperature. All water tests use fresh water. For IPX1 to IPX6 the water should be within 5 K of the specimen's temperature; for IPX7 the same 5 K limit applies. The standard warns that protection may not be satisfactory if the enclosure is cleaned with high-pressure hot water beyond the IPX9 conditions or with solvents; other liquids, such as salt water, are not tested.
- IPX5 and IPX6 jets use the same hose nozzle drawing (Figure 6): 6.3 mm and 12.5 L/min (±5 %) for 5, giving a core stream about 40 mm across at 2.5 m; 12.5 mm and 100 L/min for 6, about 120 mm across. Water pressure is whatever produces that flow.
- IPX7: enclosures shorter than 850 mm are sunk until their lowest point is 1,000 mm below the surface; taller ones until their highest point is 150 mm below. 30 minutes. A product standard may modify this if the equipment is tested while running.
- IPX9 (IEC 60529 Amendment 2, 2013): water at (80 ± 5) °C from a fan-jet nozzle set to (15 ± 1) L/min and a distributed impact force of 0.9–1.2 N. Enclosures smaller than 250 mm turn on a turntable at 5 r/min and are sprayed for 30 s at each of 0°, 30°, 60° and 90°; larger ones are sprayed from all practical directions at (175 ± 25) mm for 1 min/m², at least 3 min.
- Pass criteria. Some water may enter, as long as it does not interfere with operation or safety, does not deposit on insulation where it could cause tracking, does not reach live parts or windings not designed to run wet, and does not collect near cable ends. The product standard sets the exact amount.
- Dust (5 and 6). The enclosure sits in a chamber of circulating talcum powder (2 kg per cubic metre, fine enough to pass a 75 µm mesh). Enclosures that breathe as they heat and cool are held at up to 2 kPa (20 mbar) below ambient and must draw 80 times their volume of air through, or run 8 hours; others are simply left in for 8 hours.
Higher digits and dual codes
| First digit | A first digit includes all lower degrees: IP5X also meets IP4X. |
|---|---|
| Second digit 0–6 | Up to and including 6, a second digit includes all lower ones: IPX6 also meets IPX5 and IPX4. |
| Second digit 7, 8, 9 | Not cumulative with the jets. An enclosure marked only 7, 8 or 9 is considered unsuitable for exposure to the 5/6 water jets (and a 9-only enclosure for immersion) unless it is multiple-coded. |
| Versatile codes | IPX5/IPX7, IPX6/IPX7, IPX5/IPX8, IPX6/IPX8, IPX5/IPX9, IPX6/IPX9 and the triple codes such as IPX6/IPX8/IPX9 cover both jets and immersion. |
| Restricted codes | IPX7, IPX8 or IPX9 alone, and IPX7/IPX9 or IPX8/IPX9: suitable only for the conditions tested. |
Optional letters
| Letter | Type | Meaning |
|---|---|---|
| A | Additional (after the digits) | Back of hand kept away (50 mm sphere) |
| B | Additional | Finger kept away (12 mm × 80 mm test finger) |
| C | Additional | Tool kept away (2.5 mm × 100 mm probe) |
| D | Additional | Wire kept away (1.0 mm × 100 mm probe) |
| H | Supplementary | High-voltage apparatus |
| M | Supplementary | Water-tested with moving parts in motion |
| S | Supplementary | Water-tested with moving parts stationary |
| W | Supplementary | Suitable for specified weather conditions |
Reading a full code
- Order: IP, first digit, second digit, optional additional letter (A–D), optional supplementary letter (H, M, S, W). Examples from the standard: IP44, IPX5, IP2X, IP20C, IPXXC, IPX1C, IP3XD, IP23S, IP21CM.
- An additional letter is used only when the protection of people is better than the first digit shows (for example IP20C: the openings keep out fingers, and internal barriers also keep a 2.5 mm tool away from live parts), or when only that protection is claimed (IPXXC).
- The digits must be quoted as digits: IEC 60529 says the degree is specified only by the numeral, not by the description. The IEC notes that marketing words such as "waterproof" and "water-resistant" are hard to assess; the IP digits are what was tested.
- Common ratings decoded: IP20 = fingers kept out, no water rating; IP44 = 1 mm objects, splashing water; IP54 = dust-protected, splashing water; IP65 = dust-tight, water jets; IP66 = dust-tight, powerful jets; IP67 = dust-tight, temporary immersion; IP68 = dust-tight, continuous immersion as stated by the maker.
NEMA enclosure types and IP codes
| NEMA type | Meets or exceeds (IP) | Use |
|---|---|---|
| 1 | IP20 | Indoor; falling dirt |
| 2 | IP22 | Indoor; dripping and light splashing |
| 3, 3X, 3S, 3SX | IP55 | Outdoor; rain, sleet, windblown dust, ice |
| 3R, 3RX | IP24 | Outdoor; rain, sleet, snow (no windblown dust) |
| 4, 4X | IP66 | Indoor/outdoor; hose-directed water (X = corrosion) |
| 5 | IP53 | Indoor; settling dust, dripping water |
| 6 | IP67 | Occasional temporary submersion |
| 6P | IP68 | Prolonged submersion; corrosion |
| 12, 12K, 13 | IP54 | Indoor; circulating dust; 13 adds oil and coolant |
Why NEMA and IP do not convert both ways
- NEMA's Table A-1 converts NEMA types to the IP codes they meet or exceed; NEMA states it cannot be used to convert an IP code to a NEMA type. NEMA 250 also tests corrosion, gasket aging, icing, oil and coolants and construction details that IEC 60529 does not cover, and the IEC rain tests allow some water in where NEMA allows none.
- So a NEMA 4X box may also be marked IP66 if it passes that test, but an IP66 box is not automatically NEMA 4X.
- NEMA types 7, 8, 9 and 10 are for hazardous (classified) locations and mines and are not in NEMA's IP conversion table.
- Road vehicles use ISO 20653, which keeps the IP structure but has its own tests, including the "K" codes such as IPX9K. Those test conditions are not reproduced here because no free official summary was available.
Sources
- All documents were downloaded and read on 6 October 2026.
- IEC 60529:1989 + A1:1999 + A2:2013 (edition 2.2), Degrees of protection provided by enclosures (IP Code): clauses 4–8, Tables 1–4 and 8, clauses 13.4 and 14.2–14.3. Read from the copy incorporated by reference in U.S. federal regulations (46 CFR 110.10-1) and published by Public.Resource.Org: archive.org/details/pub.cfr.iec.60529.2013
- IEC, Ingress Protection (IP) ratings (scope: 72.5 kV, digit ranges, history since 1976), iec.ch/ip-ratings, read from the Internet Archive capture of 14 August 2026 because iec.ch refuses scripted requests.
- NEMA, A Brief Comparison of NEMA 250 and IEC 60529 (digit descriptions, why Type cannot be converted from IP). nema.org/DocUploads/388FCDA2-A544-4191-B2E187CE102C774A/250_IEC60529comparison.pdf (Internet Archive copy).
- NEMA Enclosures Section, NEMA Enclosure Types, November 2005 (definitions from NEMA 250-2003 and Table A-1, conversion of NEMA types to IP codes). nema.org/docs/default-source/products-document-library/nema-enclosure-types.pdf
Frequently asked questions
What does IP67 mean?
IP67 means dust-tight (6: no ingress of dust after an 8-hour talcum-powder test) and protected against temporary immersion (7). In the IEC 60529 immersion test, an enclosure under 850 mm tall is held with its lowest point 1 m below the surface (taller ones with the top 0.15 m below) for 30 minutes in fresh water within 5 K of the enclosure's temperature.
What is the difference between IP67 and IP68?
IP67 is a fixed test: 30 minutes, lowest point 1 m deep. IP68 means continuous immersion under conditions agreed between manufacturer and user that must be more severe than the IP67 test, so the depth and time differ from product to product and should be stated by the maker.
Is IP68 better than IP65?
Not necessarily. Up to 6, a higher second digit includes all lower ones, so IP66 also passes IP65. But 7 and 8 are immersion tests and do not include the jet tests 5 and 6: an IP68 device has not been tested against water jets unless it is dual-coded, for example IP65/IP68.
What does the X in IPX7 mean?
X replaces a digit that was not tested or not specified. IPX7 has been tested for temporary immersion but makes no claim about dust or solid objects; IP5X is dust-protected with no water rating.
What is IPX9 or IP69K?
IEC 60529 added second numeral 9 in 2013: protection against high-pressure, high-temperature water jets, tested with water at 80 °C (±5 °C) from a fan-jet nozzle delivering 15 L/min (±1): small enclosures turn on a turntable and are sprayed for 30 s at each of 0°, 30°, 60° and 90°, larger ones from 175 ± 25 mm. The older "9K" code comes from road-vehicle standards (ISO 20653) and is tested differently.