IP rating codes describe protection against access to hazardous parts, solid objects and water under defined test conditions. Read the two digits separately: one addresses access and solids; the other addresses water. Do not treat the code as a single score for enclosure quality. For an electrical panel, the useful question is whether the declared protection matches the actual exposure and the completed installation. Heat, corrosion, condensation and modified openings need separate decisions.
What the two digits tell you
IEC 60529 defines the IP code. Its first characteristic numeral addresses access to hazardous parts and entry of solid foreign objects. Its second characteristic numeral addresses harmful water ingress.
For example, IP65 combines dust-tight protection with protection against water jets under the specified tests. IP55 has the same water numeral, but its dust protection allows limited ingress within the standard's acceptance criteria. That difference matters where deposited dust could affect operation or safety.
An X means that a protection numeral has not been specified for that position. It does not mean zero protection, and it does not establish a particular protection level.
Keep these reading rules separate:
- Compare the first numerals when assessing protection against solids and access.
- Compare the second numerals against the actual water exposure.
- Treat an X as an unanswered specification question, not a passing result.
- Read any additional markings and installation conditions alongside the code.
Use the IP rating chart for the complete numeral reference. The purchasing decision needs more than identifying the digits.
Why immersion is not a higher jet rating
The water numeral identifies a test category, not a universal ranking of wet environments. This becomes especially important when comparing jet protection with immersion protection.
IP66 addresses powerful water jets. IP67 addresses temporary immersion under specified conditions. An IP67 declaration alone does not establish that the enclosure meets IP66 jet requirements.
Where both exposures occur, request evidence for both. A dual declaration such as IP66/IP67 communicates separate protection claims rather than an assumed progression.
IP68 also needs supporting conditions. Its immersion depth, duration and other agreed conditions must suit the application. The code alone does not tell you how deep the enclosure can remain submerged or for how long.
For a cleaning area, record the actual water exposure before choosing a code:
- Splashing from nearby equipment differs from a directed hose.
- A powerful jet differs from temporary flooding.
- Hot, high-pressure cleaning differs from ordinary water-jet testing.
- Chemical cleaning adds compatibility questions that the water numeral does not answer.
For the broader process of interpreting declarations and conditions, use how to read an IP rating for enclosure selection.
What an IP code does not establish
An IP code is not a complete environmental specification. IEC 60529 addresses defined ingress and access tests, not every condition an enclosure may encounter during service.
The code alone does not establish resistance to corrosion, cleaning chemicals, ultraviolet exposure, impact or prolonged outdoor aging. Separate evidence may cover those properties, but they cannot be inferred from the two digits.
It also does not establish a safe internal operating temperature. A tightly sealed enclosure can protect electronics from dust while allowing them to overheat.
Condensation is another separate problem. Moist air can be trapped during assembly or enter during servicing. If an internal surface falls below that air's dew point, water can form without an external leak.
Similarly, water-jet protection does not establish resistance to steam or water vapor. Do not specify a jet code as proof of suitability for steam cleaning.
For outdoor installations, the outdoor enclosure guide covers the additional effects of sunlight, weather and temperature cycling. Those conditions belong in the specification alongside the ingress code.
Where a NEMA type belongs in the specification
An IP code and a NEMA enclosure type are not interchangeable labels. They use different classification systems and address different requirements.
In US installations, NEC 110.28 states that IP ratings are not a substitute for enclosure type ratings. Confirm the applicable edition, project specification and approval requirements before ordering.
Do not convert an IP code into a NEMA type by matching a chart and assuming equivalence. If the project requires both declarations, request both explicitly. If it requires independent listing, confirm that requirement separately from the ingress rating.
Our enclosures are rated NEMA 4X / IP66 by the manufacturer; not UL listed. That distinction must remain visible when checking project acceptance requirements.
For a factory installation, the minimum IP rating for factory enclosures depends on the local exposure. A dry control room and a regularly washed production area do not need the same environmental specification.
Apply the rating to the completed panel
A rating describes the evaluated enclosure configuration and its installation conditions. It does not automatically transfer unchanged to every assembly built from that enclosure.
Cable glands, conduit entries, displays, windows, drains and cooling devices create additional interfaces. Each interface needs suitable components, correct dimensions and installation according to its instructions.
A gland with an appropriate rating can still leak around an undersized cable. A door gasket can fail to seal if wiring prevents the door from seating. A display seal can fail where the cutout edge is distorted or outside tolerance.
Review the completed assembly rather than collecting high ratings from individual parts. Component markings alone do not prove the assembled panel has passed the corresponding enclosure tests.
Before releasing the drawing, check:
- Every opening has a defined component or approved closure.
- Each cable diameter falls within its gland's sealing range.
- Wall thickness and mounting geometry suit the installed fittings.
- Door-mounted devices leave adequate internal clearance.
- Gaskets and sealing surfaces remain continuous and undamaged.
The article on drilling an enclosure and its rating explains why a new opening needs more than a neat hole.
Keep heat and usable space separate from ingress
Do not select enclosure dimensions from the IP code. The code does not establish backplate area, wiring space, equipment clearance or thermal capacity.
Start with component dimensions and their required installation clearances. Include terminal access, conductor bending space, cable entries and the room needed to close the door without compression against wiring.
Then calculate the heat generated inside the enclosure. Use component loss data, the maximum design ambient temperature and the lowest applicable equipment temperature limit.
An internal fan may reduce hot spots, but it does not remove heat from a sealed enclosure by itself. Adding an intake filter or exhaust fan changes the environmental design and requires another rating review.
For electronics-heavy panels, the article on PCB heat in a sealed enclosure explains the heat balance. A dimensional match alone is not evidence of thermal suitability.
What to put on the enclosure order
Write the required exposure and supporting conditions beside the code. That makes the requirement checkable during quotation, drawing approval and installation.
Avoid a description such as “waterproof control box.” It leaves the cleaning method, immersion conditions and acceptance evidence undefined.
| Specification item | What to record |
|---|---|
| Ingress protection | Required IP code and the evidence needed for acceptance |
| Water exposure | Splashing, hose cleaning, powerful jets or immersion, as applicable |
| Immersion conditions | Required depth, duration and installation conditions when relevant |
| Other environmental exposure | Dust type, chemicals, corrosion, sunlight and temperature range |
| Enclosure type and approval | Required NEMA type and any independent listing requirement |
| Material | Grade selected for the actual chemical and corrosion exposure |
| Usable dimensions | Internal height, width and mounting-panel-to-door clearance |
| Thermal design | Internal losses, maximum ambient and allowable equipment temperature |
| Openings and fittings | Cutout drawing, component details, cable diameters and entry locations |
| Installation | Mounting orientation, support arrangement and service access |
When those requirements are defined, use the enclosure selector to compare environment, listing requirements and usable dimensions. Check heat separately before accepting a dimensional match.
Keep the enclosure drawing, fitting instructions and rating evidence with the panel documentation. Any later change to an opening, seal or cooling arrangement should trigger another environmental review.
Enclosures for this job
Catalog sizes that suit the job this article answers, picked from its subject; open one for its full specifications.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 12 × 10 × 6 in | 304 stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 20 × 16 × 8 in | 304 stainless | 20 x 16 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 24 × 20 × 8 in | 304 stainless | 24 x 20 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
What do the two digits in IP rating codes mean?
The first numeral addresses access to hazardous parts and entry of solid foreign objects. The second addresses harmful water ingress under defined tests. Read them separately, then compare the declared protection with the enclosure's actual installation and exposure.
Is IP67 always better than IP66?
Not for every water exposure. IP67 addresses temporary immersion, while IP66 addresses powerful water jets. An IP67 declaration alone does not establish IP66 protection. Where both exposures occur, specify both requirements and request supporting evidence for the intended configuration.
What does X mean in an IP code?
An X means that a protection numeral has not been specified in that position. It does not mean zero protection, but it also does not establish a particular level. Ask for the missing declaration if that exposure matters to the installation.
Does an IP rating prove an electrical enclosure is suitable for the whole application?
No. An IP code addresses defined ingress and access tests. It does not establish thermal suitability, corrosion resistance, condensation control or every approval requirement. The completed panel also needs correctly installed fittings, suitable materials and enough usable space for equipment and wiring.
