A specification sheet lists IP54 on one charger and IP65 on another, and the buyer reads it as one being better sealed. That reading is roughly correct and almost entirely unhelpful, because the two numbers answer a narrow question about water and dust while the failures that actually occur on site come from impact, condensation and salt.
Three separate rating systems cover those three separate problems, and they are not interchangeable. Reading them properly turns a single number on a datasheet into a description of where a unit can and cannot be installed.
The Two Digits Do Not Mean What Buyers Think
An IP code has two positions. The first digit describes protection against solid objects, running from no protection up to dust-tight. The second describes protection against water, running from dripping up to continuous immersion and, in the extended form, high-pressure jets at elevated temperature.
The confusion starts at the middle of the water scale. A rating whose second digit is four means protection against splashing water from any direction. It does not mean the enclosure can be washed down with a hose, and it does not mean it survives standing water. A rating with five means protection against water jets; the higher forms mean more forceful jets, immersion for a defined time, or continuous immersion.
This matters because site cleaning practice is not specified by the rating. An operator who pressure-washes a row of units rated for splashing has voided the assumption the design was based on, and the resulting water ingress looks like a manufacturing defect.
The first digit has a similar subtlety. A rating of five permits limited dust ingress that does not interfere with operation. Only six is dust-tight. For a charger, the practical difference between five and six is often less important than the filter arrangement, because the enclosure is usually ventilated anyway and the filter is doing most of the work.
IPX4 and IPX5: The Test Difference
The tests behind the digits are physically different, not simply scaled up.
Splash testing uses a controlled spray or an oscillating tube that delivers water against the enclosure from all sides at low pressure. Jet testing uses a nozzle directing a concentrated stream at the enclosure from a defined distance, at a pressure high enough to force water into gaps that splash would not reach. The second test is aimed at the failure mode that rain does not produce but a hose does.
Neither test addresses immersion, and neither simulates the repeated wet-dry cycling that a unit actually experiences. A charger in a coastal car park is wetted by rain, dried by sun, wetted again, and coated with salt the whole time. That cycle stresses seals and accelerates corrosion in a way a single test at one moment cannot capture.
IK Is a Separate Rating
Impact resistance is expressed as an IK code, with numbers running from no protection up to a level intended for heavy impacts. Each step corresponds to a higher impact energy, delivered in a defined way, and the rating is about the enclosure surviving that energy without compromising its function.
The most common mistake is to treat one IK number as covering the whole product. On a charger with a display, the screen is a separate component with its own vulnerability, and a housing rated for high impact can contain a display rated lower. DC units in this class commonly carry a high IK rating for the enclosure and a lower one for the screen, and both figures are meaningful: the first describes what happens when a vehicle door swings into the cabinet, the second describes what happens when something strikes the display.
Impact damage is also cumulative in a way that ratings do not express. An enclosure that survives a defined blow may still be left with a distorted gasket or a hairline gap, and the water protection it was tested for is now compromised. This is why a unit with visible impact damage should be treated as a candidate for a seal inspection rather than simply as cosmetically marked.
Condensation: The Gap Neither Rating Covers
Neither IP nor IK addresses the failure that accounts for a large share of water-related damage in temperate climates: water forming inside a sealed enclosure without any water entering from outside.
The mechanism is the breathing cycle. Air inside the enclosure warms while the charger runs, expands, and pushes out through seals and cable glands. When the unit goes idle and cools, that air contracts and draws moist outside air back in. Repeat this daily through a humid season and the interior accumulates moisture, which then condenses on cold surfaces when the temperature drops. The electronics are wet without a single drop having come through the housing.
Design responses exist and they are visible in a specification if you look for them. A pressure-equalisation vent allows air to move without carrying liquid water or dust. An internal heater keeps the enclosure above the dew point when the unit is idle. Conformal coating protects the boards that are exposed regardless. Sealing more tightly without addressing pressure, by contrast, tends to move the problem rather than solve it, because the enclosure then breathes through the cable glands instead.
For a buyer, the question is not the IP number but whether condensation was designed for. A supplier who can describe how the enclosure manages pressure is describing a decision. A supplier who answers only with the IP rating has not addressed the question.
Corrosion Class and Salt
Corrosion resistance is described by its own classification, based on the corrosivity of the atmosphere a product is expected to survive. The lower classes describe heated interiors and rural air. The middle classes describe urban and industrial atmospheres. The highest classes describe coastal and offshore environments where airborne chloride is present continuously.
The classification describes the environment, not a coating. A product declared suitable for a high-corrosivity class is making a claim about how its materials and finishes perform in that environment, and the claim is worth testing against the parts that are usually overlooked: fixings, hinges, vent covers, cable glands and the base plinth. A well-coated enclosure on galvanised legs can still fail at the fasteners that hold it down.
De-icing salt creates a related but different exposure. A unit beside a road in a cold climate sees concentrated salt spray for a season and almost none for the rest of the year, and that pattern produces pitting rather than uniform surface corrosion. Where this is expected, the corrosion class and the inspection interval belong together in the specification.
Matching the Rating to the Location
The three ratings combine differently depending on where the unit goes, and the weakest of them decides the outcome. A high IP rating with an ordinary corrosion class is the wrong combination for a coastal site. A high IK rating on the housing with a lower one on the display is a reasonable, honest specification, provided the buyer knows which applies where.
AC and DC products make the trade differently because they are installed differently. The AC wallbox range offers a tethered form and a socketed form, and the two carry different water ratings because the socketed version presents an open interface when nothing is plugged in. Both carry an impact rating suited to a wall-mounted unit rather than to a cabinet standing in a traffic lane, which is the correct comparison for that product type.
DC cabinets face the harder set of conditions. A hub host typically carries a water rating suited to outdoor installation and a high impact rating for the enclosure, with a separate and lower figure for the display. That combination is honest about where the vulnerability sits.
Three numbers answer three questions. Water and dust are one, impact is the second, atmosphere is the third, and condensation sits outside all of them.
The practical use of this is a short table in the procurement file: for each location, write the water exposure, the impact exposure and the atmospheric class, then check that the product's three ratings meet all three rather than only the first. The full ratings for each product line are listed in the technical documentation available on the download page.
Two questions separate a considered specification from a copied one. Ask how the enclosure manages internal pressure, and ask which components carry which impact rating. The answers describe a design decision; a single IP number describes only its starting point.
Specifying for a coastal or de-iced site?
Describe the exposure rather than the rating you want. Water, impact and atmosphere each need an answer, and the three do not follow from one another.
Ask a specification question