"Waterproof" is a marketing word. Engineers don't get to use it on a control plan. The control plan needs an IP rating matched to the water the enclosure actually sees.
The IP67 rating
On this page, IP67 means a dust-tight enclosure that has passed a static immersion test — not a jet test. The two digits, the IEC 60529 method, and why a jet pass does not imply an immersion pass are on the IP ratings guide. A gasket alone does not produce that rating.
Three exposures at a chassis box
These three are often written as one rating. Each is a different duty:
- Standing water at the wheel arch. A box mounted low on the chassis can sit in water during a deep puddle crossing.
- Wash‑down at depots and ports. Depot cleaning drives water into cavities that then hold standing water against the connector seal long after the lance has moved on. Note the distinction, though: a room-temperature jet is an IP66 question, and a hot high-pressure lance is a different test again — IPX9K in ISO 20653, commonly written “IP69K”. Neither is an IP67 question. The water left standing is the immersion test.
- Salt-spray on coastal routes and winter roads. Salt-laden water is not just a sealing problem; it accelerates corrosion at the connector pin and gasket interface, so the seal needs to keep its integrity over many years.
How the NBX‑971 is sealed
The gasket, the three Deutsch connectors and the vent are what the seal on the NBX‑971 depends on:
- Continuous gasket seal at the split-line. The enclosure halves are designed with a continuous gasket groove and controlled compression. The gasket compound is selected to retain elasticity across the full −40 to +85 °C working range, not just at room temperature.
- Sealed automotive connectors. The harness exit uses sealed automotive connectors with matching wire-side seals. The standard NBX‑971 build is three Deutsch harness-side housings — two DT06-12S and one HDP26-24-18PS; Bussmann, Tyco/AMP Superseal or Delphi GT are specified where a programme already stocks them. An IP65 enclosure with a non-sealed connector is not IP65. There is no shortcut here.
- Pressure-equalising vent membrane. A perfectly sealed enclosure has a pressure-differential problem under thermal cycling: warm air expands, cold air contracts, and the gasket sees stress every cycle. A semi-permeable ePTFE pressure-equalising vent membrane equalises internal pressure without admitting water.
- The figure below is the immersion method. It is not the test behind the NBX‑971 catalogue line. Our in-house environmental lab handles dust-ingress screening and environmental preconditioning; a programme that needs immersion assigns that test to the appropriate qualified facility.
What IP67 does not give you
It helps to see the boundary explicitly. IP67 is a precise statement about two things — and silent about four others that teams sometimes assume it covers:
| Protection aspect | Covered by IP67 | What it means / validate separately |
|---|---|---|
| Dust ingress (solids) | First digit "6" — dust-tight, nothing solid gets in. | |
| Water immersion | Second digit "7" — 30 min with the lowest point 1 m below the surface, per IEC 60529. | |
| High-pressure / high-temperature washing | Its own test — IPX9K in ISO 20653, IPX9 in IEC 60529, sold as “IP69K” — at roughly 80 °C and 80–100 bar. | |
| Corrosion / salt | Not an IP property — needs separate salt-spray validation. | |
| Vibration / mechanical | Not an IP property — validated separately. | |
| UV / sustained sunlight | Needs UV-stabilised material — e.g. Middle East rooftop installs. |
The table is the PDB-side cut. Why those four sit outside the number, and what evidence to ask for instead, is on the IP ratings guide.
Which rating to specify
IP67 is right when the enclosure can see immersion. A body-cavity install that does not see water does not need that rating. NBX‑957 and NBX‑953 (47-way) are the body-cavity references, both published at IP5X, so the water digit is not declared.
Across a whole vehicle, which IP level does each mounting position actually need? sets out the five zones and the evidence to request behind any rating.
| Installation scenario | What to specify | Reference product |
|---|---|---|
| In-cabin / body cavity, no water exposure | IP5X | NBX‑957 body-central PDB |
| High-circuit-count body harness, sheltered | IP5X | NBX‑953 (47-way) |
| Chassis rail — spray and wheel-thrown water | IP65 | NBX‑971 |
| Chassis-mount / near-wheel — can see immersion | IP67 | No NBX distribution box in this catalogue publishes IP67. Specify the immersion test if the position needs it. |
| Hot pressure wash aimed at the box | IP69K | No NBX distribution box in this catalogue publishes IP69K. Specify that test if the position needs it. |
What to send to a supplier when you need IP67
- The installation location on the vehicle (chassis, body cavity, under-floor, near-wheel).
- The working temperature range (−40 to +85 °C or specific target).
- The connector standard required by the harness drawing.
- The circuit count and current rating (or alternatively the harness drawing itself).
- Any region-specific approval requirements (e-Mark / ECE, SASO, FCC) — these are available upon project requirement, not blanket-claimed.
- Mass-production volume, sample timing, target launch.
If the position can see immersion, write the immersion test into the specification.
To request drawings or a sealing strategy quote against your harness, please use the contact page or WhatsApp — typical reply within one business day.