How to Read an IP Rating: IP65, IP66, IP67 and NEMA Equivalents
How to Read the IP Code: Each Digit Covers One Thing
The IP (Ingress Protection) code comes from IEC 60529 (the corresponding national standard is GB/T 4208). The first digit covers solids and dust (0–6), the second covers water (0–8). Read the code by splitting the digits first, then matching them to the application:
First Digit: Protection Against Solids and Dust (0–6)
| Digit | Protection Meaning | Typical Application |
|---|---|---|
| 0 | No protection | — |
| 1 | Protected against solid objects ≥50 mm (back of hand) | — |
| 2 | Protected against solid objects ≥12.5 mm (fingers) | Basic protection |
| 3 | Protected against solid objects ≥2.5 mm (tools, cables) | General indoor |
| 4 | Protected against solid objects ≥1.0 mm (thin wires, screws) | Indoor industrial environment |
| 5 | Dust protected: limited dust ingress permitted without affecting operation | Dusty workshops, general outdoor |
| 6 | Dust-tight: no dust ingress | Outdoor, heavy dust environments |
Second Digit: Protection Against Water (0–8)
| Digit | Protection Meaning | Typical Application |
|---|---|---|
| 0 | No protection | — |
| 1 | Vertically falling water drops | Under an indoor ceiling |
| 2 | Water drops up to 15° from vertical | Indoor areas with minor condensation |
| 3 | Spraying water (60° range) | Sheltered semi-outdoor areas |
| 4 | Splashing water (from all directions) | Adjacent to washdown areas |
| 5 | Water jets (6.3 mm nozzle, all directions) | General outdoor applications |
| 6 | Powerful water jets (12.5 mm nozzle, high flow) | Open-air exposure, marine environments |
| 7 | Temporary immersion (0.15–1 m, 30 minutes) | Areas prone to standing water / brief flooding |
| 8 | Continuous immersion (per agreed conditions) | Underwater installation (custom build) |
Common IP Ratings and Applications — Quick Reference
| Rating | Meaning at a Glance | Typical Installation Environment |
|---|---|---|
| IP54 | Dust-protected + splash-resistant | Indoor workshops, plants with light dust |
| IP55 | Dust-tight + light water jet protection | Indoor humid areas, pump rooms with condensation risk |
| IP65 | Dust-tight + water jet protection | Most common rating for outdoor cabinets (requires rain hood) |
| IP66 | Dust-tight + powerful water jet protection | Open-air exposure, docks, storm-prone areas |
| IP67 | Dust-tight + temporary immersion protection | Locations prone to standing water and brief flooding |
How do IP and NEMA ratings compare?
Overseas projects often ask "what IP rating is equivalent to NEMA 4X?" An approximate cross-reference can be provided, but keep in mind:The comparison is a one-way approximation, not an equivalence — the NEMA system also evaluates corrosion resistance, ice resistance and other factors that IP does not cover.
| NEMA type | Approximate IP rating | Additional NEMA criteria (not covered by IP) |
|---|---|---|
| NEMA 1 | ≈ IP20 | — |
| NEMA 12 / 12K | ≈ IP54–55 | Dust-tight, dripping oil (no ingress of dripping liquid) |
| NEMA 3 / 3X | ≈ IP64 | Outdoor rain and snow, ice-resistant (X suffix) |
| NEMA 4 / 4X | ≈ IP65–66 | Hosedown from all directions; 4X adds a corrosion-resistance requirement |
| NEMA 6 / 6P | ≈ IP67–68 | Short-term/long-term immersion, no damage on water ingress |
Basis: IEC 60529 / GB/T 4208 (IP system), NEMA 250 and UL 50E (NEMA/Type system). The comparison is an engineering reference; selection is governed by the target market's code.
Five common misconceptions
- "A higher number is stronger across the board"— Not true. IP67 is an immersion test; for long-term outdoor service, what matters more is dust-tightness plus hosedown (IP65/66);
- "NEMA and IP can be converted directly"— The test methods differ, so only an approximate comparison is possible;
- "The rating on the report equals the rating in the field"— An IP rating assumes as-shipped condition and correct installation; field cutouts and glands that are not sealed tight void the rating on the spot;
- "A high IP rating means no condensation"— Condensation is unrelated to the ingress protection rating; it comes from the temperature difference and humidity between inside and outside the cabinet, and is solved with a heater / breather valve;
- "One report covers all models"— A report corresponds to the structure submitted for testing; custom structures should be submitted for testing as the actual model (this is also how we cite our reports).
Selection advice: set the rating by installation location
- Indoor electrical room / dry workshop — IP54 is sufficient; focus shifts to heat dissipation and ease of operation;
- Outdoor with a canopy — IP55 + rain hood;
- Outdoor, no canopy — Start at IP65, with a rain hood and bottom-entry sealing;
- Fully exposed / coastal salt spray — IP66 + 316L or powder coat plus passivation;
- Pump room / areas prone to standing water — IP66 with a raised foundation; evaluate IP67 with a condensation countermeasure as needed.
FAQ: Common questions about ingress protection ratings
Common questions about ingress protection ratings
What is the difference between IP65 and IP66?
The difference is in the second digit: 5 = protected against water jets from all directions (6.3 mm nozzle); 6 = protected against powerful water jets (12.5 mm nozzle, higher flow). Dust protection is the same for both (first digit 6 = dust-tight). For most outdoor cabinets IP65 is sufficient; choose IP66 for heavy washdown, storm exposure or deck-type locations.
Is IP67 always better than IP65?
No. IP67 covers short-term immersion (0.15–1 m, 30 minutes) and targets installation locations that may see standing water or even flooding. For most outdoor cabinets, the governing criteria are dust-tightness plus hosedown (IP65/66); immersion-rated enclosures also face condensation from the temperature-driven breathing cycle, which requires a heater/dehumidifier. A higher number is not automatically a better fit.
What IP rating does NEMA 4X correspond to?
In engineering practice it is often approximated as IP66. However, NEMA 250 also includes additional requirements such as corrosion resistance and ice resistance, and its test methods differ from IEC 60529, so the two cannot be equated directly; if the target market specifies NEMA, verify to the NEMA system.
Can a custom cabinet achieve IP66 / IP67?
Yes. Sealing is designed to the target rating: double-folded door frame + foamed gasket + correct glands and cutout sealing. Custom structures can be sent to a third-party lab to obtain an IP report specific to the actual model.
What rating are your existing IP reports?
IP65 test report for the AK series carbon steel enclosure, dated 2022-08-22 — original on file, report number verifiable. Testing is per configuration; we do not apply one report to every model.
Not sure which rating your application needs?
Send us the installation location (indoor / outdoor / pump room / deck) and the environment (dust, salt spray, washdown), and our engineers will recommend the rating and enclosure design for the application.
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