What the IP rating actually means
IP — Ingress Protection — is the general-purpose classification (IEC 60529, adopted in China as GB/T 4208) for how well an enclosure resists dust and water. It is a two-character code: the first character is solids (dust), the second is water. Road vehicles also have a scheme of their own, ISO 20653, whose codes carry a K and are not interchangeable with the ones in this table.
| Rating | Solids | Liquids | Typical use case |
|---|---|---|---|
| IP54 | Dust-protected | Splashing water | In-cabin fuse boxes, sheltered electronics |
| IP65 | Dust-tight | Water jets, 6.3 mm nozzle | Chassis-mounted PDBs, exposed bus electronics |
| IP66 | Dust-tight | Powerful water jets, 12.5 mm nozzle | Roof equipment and chassis positions in the direct spray path |
| IP67 | Dust-tight | Temporary immersion, 30 min — lowest point 1 m below the surface for enclosures under 850 mm tall | Excavators, off-road construction, agricultural machinery |
One point is worth stating plainly, because it is the most common misreading of the table above: the second digit is not a ladder. IP67 is not "IP66 plus more" — jets and immersion are separate tests for separate failure modes, and passing one does not predict the other. In particular, IP67 says nothing about high-pressure or high-temperature washing: that duty has its own test — IPX9K in ISO 20653, IPX9 in IEC 60529, and commonly written “IP69K” after the DIN 40050-9 standard ISO 20653 replaced — at roughly 80 °C and 80–100 bar. If a part is going to meet a pressure washer or a steam lance in service, specify that duty and its test method separately rather than reading it into an IP67 line on a datasheet.
This page covers how we design and validate sealed enclosures. If you are still deciding which level a given position needs — including how the ISO 20653 automotive codes differ from the IEC 60529 ones quoted above, and what evidence to request behind any supplier's rating — our guide to IP ratings for commercial-vehicle electronics works through that decision by mounting position.
Where IP65 / IP67 matters in your program
| Application | Typical exposure | Recommended IP |
|---|---|---|
| Heavy trucks & logistics | Chassis-mounted central PDBs see road spray, salt and washdown. | Set by position rather than by region: IP65 where the box sits clear of direct jets, IP66 in the spray path, IP67 where the position sees standing water or fording. |
| Construction machinery | Excavators, loaders and graders are parked outdoors, run through dust storms and cleaned down between shifts — see NBX‑961 excavator integrated box. | IP67 for dust and immersion; where the cleaning routine uses a pressure washer, specify that duty separately. |
| Buses & coaches | Roof equipment exposed to direct rain; chassis equipment to road spray. | IP65 on sheltered chassis positions; IP66 where roof or chassis hardware sits in the direct spray path. |
| Agricultural machinery | Sustained dust ingress, occasional washdown. | IP66 for jet cleaning, IP67 for standing water — separate tests, so specify whichever the position actually meets. A hot high-pressure lance is a third test again (IPX9K). |
How we design for IP65 / IP67
Enclosure construction
Sealing starts with the enclosure split-line. We design with continuous gasket grooves, controlled compression and known-cure sealant compounds rather than retrofitting silicone after assembly. Wall thickness, rib geometry and venting strategy are chosen to maintain seal integrity through thermal cycling.
Sealed connectors
An IP-rated enclosure with a non-sealed connector is not actually IP-rated. NBX‑971 and the other IP67 variants ship with sealed automotive-grade connectors and matching gland or bulkhead seals at the harness exit. The family is fixed per programme — commonly Bussmann, Tyco/AMP Superseal, Delphi GT or Molex MX150, or whatever a plant already stocks tooling and terminals for. The buyer-side view of that choice — which families suit which mounting position, which half of the joint you are ordering, and what a sealed connector quotation usually leaves out — is set out in the automotive connector selection guide.
Pressure equalisation
A perfectly sealed enclosure has a pressure-differential problem during thermal cycling: warm air expands, cold air contracts, and the gasket sees stress every cycle. We use semi-permeable ePTFE pressure-equalising vent membranes on outdoor enclosures so the inside pressure equalises without letting water through.
Validation
Every IP-rated NBX variant is verified to the applicable IEC 60529 method before mass production. Our in-house environmental lab handles dust-ingress screening and environmental preconditioning. The programme validation plan assigns water-ingress testing to the appropriate qualified facility, with traceable equipment, a documented sample configuration and agreed pass criteria. Where independent evidence is required, testing is completed by a qualified third-party laboratory. Results can be included in the PPAP package when a programme calls for one.
Reference products with IP rating
- NBX‑971 Waterproof Central Distribution Box — IP67, sealed connectors, −40 to +85 °C, designed for heavy trucks and off-road equipment.
- NBX‑961 Excavator Integrated Box — IP67 sealed enclosure for construction-machinery duty cycles.
- NBX‑968 Sealed Electrical Box — IP65 outdoor sealed enclosure for chassis-mount applications.
Other NBX models can be specified with an IP65 / IP67 variant on a project basis. For non-standard sealing (an IP68 immersion depth and duration agreed in writing, or the IPX9K hot pressure-wash duty usually written “IP69K”), please contact the engineering team directly via WhatsApp or email.
What we don't claim
We don't badge the entire NBX series as IP67. IP rating is a per-variant validation result — claiming a blanket rating across a 24-model family is misleading. The models above carry the class each one was actually tested to — IP67 on the NBX‑971 and NBX‑961, IP65 on the NBX‑968 — and the rest of the family carries the rating documented in its own spec.