Complete Guide to IP Ratings: What IP54, IP64, IP66 and IP67 Actually Measure
The full IEC 60529 test parameter table: nozzle diameters, flow rates, pressures, immersion depth and duration. The critical rule that IP67 does not cover IP66, the role of the seal and the cable gland, which standard IP69K actually lives in, and the NEMA equivalents.
An IP code measures only two things: solid object/dust ingress and water ingress. Corrosion, icing, seal ageing, oil resistance and explosive atmospheres are outside the scope of IEC 60529. That is why reading "IP67" as "durable under any condition" is wrong — you have to know which test was passed.
Structure of the code
IP + 1st digit (solid objects / dust) +
2nd digit (water) + optional additional letter (A/B/C/D) + optional
supplementary letter (H/M/S/W). A digit that is not tested or not declared is written
as X: IPX7 means the dust side has not been declared.
First digit: solid objects and dust
| Digit | Protection | Test probe / condition |
|---|---|---|
| 0 | No protection | — |
| 1 | ≥50 mm solid objects (back of hand) | Ø50 mm sphere |
| 2 | ≥12.5 mm (finger) | Ø12.5 mm sphere / jointed test finger |
| 3 | ≥2.5 mm (tool, thick wire) | Ø2.5 mm rod — no ingress at all |
| 4 | ≥1.0 mm (thin wire, screw) | Ø1.0 mm wire — no ingress at all |
| 5 | Dust protected | Talc powder chamber; no dust in a quantity that would impair operation |
| 6 | Dust-tight | Talc powder chamber; no dust ingress at all |
The conditions of the dust test are defined as well: the talc powder is passed through a 75 µm sieve, fed into the chamber at a dosage of 2 kg/m³ and kept continuously in suspension; for enclosures whose internal pressure drops, the depression is set so that it does not exceed 2 kPa. The duration is determined by the ability to draw 80 times the enclosure volume in air.
Second digit: water — the actual test parameters
| Digit | Protection | Test parameters | Duration |
|---|---|---|---|
| 1 | Vertically dripping water | Drip box, equivalent to 1 mm/min rainfall | 10 min |
| 2 | Dripping at 15° tilt | Sample is tilted 15° in 4 different directions | 2.5 min in each position |
| 3 | Spraying water (up to 60° from vertical) | Oscillating tube or spray nozzle at 10 l/min, 50–150 kPa | at least 5 min |
| 4 | Splashing water (from any direction) | Same flow/pressure as IPX3, extended to ~180° | at least 5 min |
| 5 | Water jet | Ø6.3 mm nozzle, 12.5 l/min, ~30 kPa, 2.5–3 m distance | at least 3 min |
| 6 | Powerful water jet | Ø12.5 mm nozzle, 100 l/min, ~100 kPa, ~3 m distance | at least 3 min |
| 7 | Temporary immersion | Lowest point at 1 m depth (for small enclosures, highest point 150 mm below the surface) | 30 min |
| 8 | Continuous immersion | Conditions agreed with the manufacturer; must be more severe than IPX7 | as agreed |
| 9 / 9K | High pressure + hot water jet | 14–16 l/min, 80–100 bar, 80 °C water, 100–150 mm distance, 0°/30°/60°/90° | 30 s at each angle |
The critical rule: IP67 does not cover IP66
Water protection levels are not cumulative beyond IPX6. A device certified to IPX7 does not automatically provide IPX5 or IPX6 protection. The reason is physical: the immersion test applies static hydrostatic pressure while the jet test applies dynamic, localized pressure; the two stress the seal geometry in completely different ways.
Practical consequence: a receiver enclosure marked "IP67" is not guaranteed to survive washdown with a pressure hose. In facilities where washdown is a risk, IP66 must be specified separately, and a dual IP66/IP67 declaration requested if needed.
Additional and supplementary letters
The additional letter (A/B/C/D) is used when protection against access to hazardous parts by
persons is higher than what the first digit implies: A = back of hand (Ø50 mm sphere),
B = finger (Ø12 mm × 80 mm jointed finger), C = tool (Ø2.5 mm rod), D = wire
(Ø1.0 mm). For example IP2XD is an enclosure protected against 12.5 mm objects
but in which a hazardous part cannot be reached even with a 1 mm wire.
Supplementary letters: H high-voltage apparatus, M water test performed with moving parts in motion, S performed at standstill, W additional measures are in place for the specified weather conditions.
Which standard is IP69K in?
The "9K" designation does not exist in IEC 60529; it originates from the German DIN 40050-9 standard, which has given way to ISO 20653. IP69 without the K was later added to IEC 60529, and the test parameters are largely the same. IP69K always comes together with IP6X and is typically required for food processing, CIP/SIP cleaning, agriculture and construction machinery. However, it does not imply IPX7/IPX8 immersion protection — an enclosure that withstands a pressurized hot water jet can leak when submerged.
NEMA equivalents — and why they are not one-to-one
The conversion is one-way: an approximate IP equivalent can be stated for a NEMA type, but a NEMA type cannot be derived from an IP rating. NEMA 250 also includes tests that do not exist in IP at all: corrosion resistance (salt spray for 4X), the effect of icing, seal ageing, oil resistance, and structural requirements for the cover.
| NEMA type | Approximate IP | Note |
|---|---|---|
| 1 | IP10 – IP20 | Indoor, contact protection |
| 3 / 3R | ~IP54 | Outdoor, rain/snow |
| 4 / 4X | diverges across the IP55 – IP66 range | The corrosion part of 4X has no IP equivalent |
| 6 / 6P | ~IP67 | Temporary / prolonged immersion |
| 12 | IP52 – IP54 | Industrial indoor |
When writing a specification, avoid definitive statements such as "NEMA 4 = IP66"; sources do not agree on this mapping. Document both ratings separately.
IP is a property of the system, not of the box
The declared rating is valid only for the configuration in which it was tested. If any one of the following changes, the rating drops or becomes void:
- If the cable gland is selected in the wrong diameter range. The gland's seal around the cable and against the enclosure wall are two separate points; if even one fails, the system loses its protection.
- If the gland's own IP rating is lower than the enclosure's: IP67 enclosure + IP54 gland = IP54 system.
- If the seal material, tightening torque, thread type or mounting method changes, the original test report loses its validity.
- If unused gland holes are not closed with plugs of an appropriate rating.
Condensation and breathing
IP67 blocks liquid water ingress, it does not block condensation. Outdoors, where temperature swings between day and night, the humid air inside the enclosure condenses on the electronics as it cools; this is a source of corrosion and leakage current. In addition, a fully sealed enclosure produces a pressure differential as temperature and altitude change, that differential loads the seal, and the enclosure can draw water in from outside while cooling. The solution is a pressure equalisation element with an air-permeable, water-impermeable membrane.
Do not confuse it with the IK code
IP is ingress protection; IK is mechanical impact protection and is defined by EN/IEC 62262. The two are independent: an IP68 plastic enclosure can be broken with a single hammer blow. Reference points: IK07 = 2 J, IK08 = 5 J, IK10 = 20 J; IK11 = 50 J was added in 2021. The test is performed with 5 impacts distributed evenly over the enclosure surface. Where there is forklift traffic or a risk of falling material, the IK code should be asked for as well.
IP mapping across AXI products
| Product | Declaration | What it means / what to watch |
|---|---|---|
| SF100 / SF200 transmitter (LF200) | IP64 | Dust-tight + resistant to splashing water from any direction. Immersion and pressurized water are out of scope. The battery cover seal is critical. |
| SF200 receiver (LT200R) | IP67 | Dust-tight + 1 m / 30 min immersion. For pressure washdown, IP66 must be specified separately. |
| ST100 / ST200 transmitter (LT200) | IP67 | The charging socket cover is the weakest link — IP67 does not apply with the cover open. |
| ST200 (transmitter + receiver) | IP67 + IP67 | The most consistent configuration at system level; suitable for field mounting without a cabinet. |
| KS250 | IP45 | Not dust-tight (first digit 4). Not suitable for a dusty workshop. |
| PT500 | IP67 | Outdoors, a breather / desiccant should be considered for condensation risk. |
| LFT20 (galvanized enclosure) | IP66 | Resistant to powerful jets but not immersion protected; must not be mounted where it can end up submerged in standing water. |
| HCT400 / HCT402 | IP67 | The −20 / +85 °C range of the HCT402 means a wide swing; the seal must keep its flexibility across that range. |
| GS740 metal pushbutton | IP67 | A pushbutton's IP rating usually applies only to the front panel side; the rear terminals must be protected separately. |
Which IP for which environment?
| Environment | Recommended minimum |
|---|---|
| Inside a cabinet, clean indoor | IP20 |
| Dusty workshop | IP54 / IP5X |
| Outdoor, rain, splashing | IP65 |
| Outdoor + hose washdown | IP66 |
| Risk of submersion in standing water | IP67 |
| Continuously underwater | IP68 (conditions agreed with the manufacturer) |
| Food / agriculture, hot high-pressure washdown | IP69K + IP67 as well |
| Vandalism / impact risk | IP + IK08–IK10 as well |