# IP Rating: Reading the Two Digits Correctly > An IP rating states how well an enclosure resists ingress, using two digits: the first for solid objects and dust, the second for water. IP65, for example, is dust-tight and protected against water jets. The digits describe tested resistance to specific conditions, not general robustness. ## Why it matters on a project IP ratings appear on almost every electrical and lighting item in a specification, and they are among the most casually copied numbers in the industry — carried over from a previous project, or chosen because a higher number feels safer. The consequence of getting it wrong is not usually immediate. It is corrosion, moisture ingress and equipment failure appearing a year or two later, in locations that are inconvenient to reach. ## Reading the code | Position | Protects against | Range | | --- | --- | --- | | First digit | Solid objects and dust | No protection → dust-tight | | Second digit | Water | No protection → immersion | The second digit is the one most often misread. The water tests describe **different conditions** — dripping, spraying, splashing, jets, immersion — and they are not a single scale where a higher number covers everything below it. An enclosure tested for immersion is not automatically suitable for high-pressure jet cleaning unless it is marked for both. Classification is defined by **IEC 60529**, with **IS 12063** as the corresponding Indian classification. ## Installation decides whether the rating is real This is the part that matters most on site. An IP-rated enclosure achieves its rating **as tested and correctly assembled**. It loses it when: - A hole is drilled without a sealed gland - The wrong gland is used, or one is left off - A gasket is omitted, damaged or misaligned - The lid is over-tightened and distorted, or under-tightened - The enclosure is installed in an orientation it was not tested in None of those show up at handover. All of them show up later as moisture inside an enclosure that was specified correctly. ## What IP does not cover - **Impact.** A separate classification; a sealed enclosure can still be fragile. - **Corrosion.** Material and finish matter separately, particularly in coastal or chemically aggressive environments. - **Heat.** Sealing an enclosure restricts cooling, and equipment inside may need the heat considered. - **UV.** Plastic enclosures outdoors degrade under sun regardless of IP rating. ## Common mistakes - **Assuming higher is always better.** The water tests are different tests. - **Copying ratings from a previous project.** Exposure differs by location. - **Breaking the rating during installation.** Glands and gaskets are part of it. - **Specifying for the room, not the position.** A fitting under an open soffit faces different conditions from one in the middle of the same space. - **Forgetting impact where equipment gets knocked.** IP says nothing about it. - **Ignoring the cleaning regime.** A space that will be hosed down is a very different requirement from one that is mopped. ## Standards referenced Degrees of protection provided by enclosures in **IEC 60529** and **IS 12063**; electrical installation practice in **IS 732**. The required rating for a specific location and installation must be determined by the project's electrical consultant. ## Frequently asked questions ### What do the two digits actually mean? The first digit is protection against solid objects and dust, running from no protection up to dust-tight. The second is protection against water, from none, through dripping, spraying and jets, to immersion. So the first digit of 6 in IP65 means dust-tight, and the second digit of 5 means protected against water jets from any direction. ### Is a higher second digit always better? Not necessarily, and this is the common misreading. The water tests are different tests, not simply increasing severity — protection against powerful jets and protection against prolonged immersion are different conditions. An enclosure rated for immersion is not automatically rated for high-pressure jets unless it is tested and marked for both. Match the rating to the actual exposure rather than assuming higher is safer. ### Where do ratings get wrongly assumed on projects? Light fittings in covered but open areas, external junction boxes, equipment in wash-down areas, and anything specified for indoors that ends up on a terrace or in a plant room open to weather. Also fittings that are correctly rated but installed so the cable entry or gland breaks the rating — the enclosure's rating only holds if it is installed as tested, with the right glands and seals. ### Does the rating survive installation? Only if installation respects it. Drilling an unsealed hole, using the wrong gland, leaving a gasket out, or over-tightening and distorting a lid all break the protection the enclosure was rated for. The rating belongs to the assembled, correctly installed unit, not to the part number on the order. ### Does IP cover impact resistance? No. Impact resistance is a separate classification, sometimes expressed as an IK rating. An enclosure can be highly sealed and easily damaged, which matters in car parks, plant rooms, warehouses and any location where equipment gets knocked. If impact is a concern, it has to be specified separately. ### What rating should be used where? It follows from the actual exposure — dust, splashing, cleaning method, weather, whether the location is washed down. There is no universal answer, and the requirement for a specific installation must be determined by the project's electrical consultant against the applicable standards and the conditions on site. ## Sources - [IEC 60529](https://webstore.iec.ch/en/) — Degrees of protection provided by enclosures (IP code) - [IS 12063](https://standards.bis.gov.in/website/published-standards/department-wise) — Classification of degrees of protection provided by enclosures - [IS 732](https://standards.bis.gov.in/website/published-standards/department-wise) — Code of practice for electrical wiring installations --- Source: https://hagerstone.com/glossary/ip-rating