IP Rating Chart: What Every IP Code Means for Electrical Equipment

An IP rating is two digits, and IEC 60529 defines each one separately. The first digit covers solids and contact, from 0 to 6. The second covers water, from 0 to 9K. So IP44 means protection against solid objects over 1 mm plus splashing water from any direction, IP66 means dust tight plus powerful water jets, and IP67 means dust tight plus temporary immersion. The two digits are independent: a product can be dust tight and still fail a jet test, or shrug off a jet and leak when submerged.

How to read the code

The rating is written IP followed by two characters, then optional letters. IP 6 6: the first 6 is the solid-particle and contact grade, the second 6 is the water grade. Where a product has been tested for one and not the other, the untested position is written as X, which is why IPX4 appears on equipment that never claimed a dust grade. An X is not a zero; it means the property was not tested or not claimed.

Two suffixes matter in practice. Letters such as W, F or M describe special conditions and are rarely relevant to panel equipment. The K in IP69K is different: it denotes a rating written specifically for high-pressure, high-temperature cleaning of road vehicles rather than a higher grade of IP69.

First digit: solids and contact

The jump from 5 to 6 is the one buyers misread. A grade 5 enclosure is dust protected, and the standard explicitly allows dust to enter provided it does not interfere. A grade 6 enclosure is dust tight with no measurable ingress. For a dusty cement plant or a flour mill that distinction is the whole decision.

Second digit: water

Grades 7 and 8 are not a sequence in the way the other digits are. Grade 8 has no fixed depth or time in the standard: the manufacturer declares the condition, and it must be more severe than grade 7. Two IP68 products from different suppliers can therefore have very different real performance, which is why an IP68 claim on its own is not a specification.

The combinations buyers actually specify

IP44, IP66 or IP67: the three-way decision

Most industrial socket enquiries land on one of three answers, and the deciding question is what happens to water after it hits the product.

IP44 is the indoor industrial default: a shed, a workshop, a covered yard. Rain that never falls is not a test the product has to pass, and specifying higher costs money without adding protection.

IP66 is the answer when water arrives under pressure — a hose, a jet wash, a deck washdown. The 12.5 mm nozzle test at 100 L/min is a genuinely violent test, and a joint that survives splashing will not necessarily survive it.

IP67 is for the case where the product may be briefly under water: a temporary distribution box left on wet ground, a pit that floods in a storm. It is not a claim that the product can be stored submerged, and it does not imply resistance to a pressure jet aimed at a seal.

The narrower comparison between the two most commonly confused grades is worked through in IP44 versus IP66 industrial plugs and sockets.

The ceiling for a 32 A industrial socket, its pin arrangement and its cable entry is covered separately in the 32 A industrial socket specifications.

Where the rating is lost: installation, not product

A tested IP66 enclosure installed with an untested cable entry is an IP44 assembly at best. The rating belongs to the complete enclosure as tested, and three routine installation choices quietly break it.

The cable entry. A gland that is not matched to the cable diameter leaves an annulus that passes water straight into the box. The rating of the gland has to match the rating of the box, and the gland has to be tightened onto the sheath, not the conductors. Cable gland selection covers the sizing rule.

The cover and the fixings. A lid seal compressed unevenly, or a missing screw at one corner, produces a path that no laboratory test would have found. This is the most common field failure on socket boxes that leave the factory with a valid rating.

Condensation. A sealed box that cycles between day and night temperatures draws moisture inward through its own seals as the internal air contracts. A truly sealed enclosure in a humid climate can therefore be wetter inside than a ventilated one. Where that matters, the answer is a breather or a drain, not a higher IP digit.

IP is not IK

Ingress protection says nothing about mechanical impact. That is a separate rating, IK, from 00 to 10, tested by dropping a defined mass from a defined height onto the enclosure. An IP66 box with a thin lid can still crack when a spanner falls on it. Outdoor and workshop equipment usually needs both figures, and catalogues that print only the IP number are telling you half the story.

Matching the grade to a real product

Portable socket boxes are a useful worked example because the whole assembly — box, sockets, breaker, cable and plug — has to hold the same grade. YOMIN's YMAX-801 carries a protection grade of IP67 and the YMAX-803 is rated IP66, both built in flame-retardant polycarbonate for temporary and portable power distribution. Each unit in the datasheet is fitted with a 1P 32 A residual current device, a 1P 63 A miniature circuit breaker, three 3P 16 A industrial sockets, a 2 m 2.5×3 supply line and a 3P 16 A plug.

The difference between the two models is instructive: the same socket arrangement, the same breaker complement, and a different water grade. That is what buyers are paying for at the top of the range, and it is why the grade has to be written on the enquiry rather than assumed from a photograph.

Panel-internal parts work the other way round. A brass DIN rail terminal block such as the ym-0209 has no meaningful ingress rating of its own, because it is not an enclosure: its environment is set entirely by the box it is mounted in. Asking for an IP rating on a terminal block is the wrong question; the right one is what the enclosure achieves with that terminal inside it.

What to write on the specification

A specification that says “waterproof box” produces a quotation for whichever grade the sales engineer prefers. A specification that says IP66 with a 20 mm gland entry and IK08 produces a comparable offer from every supplier.

Frequently asked questions

Is IP67 waterproof?

It is protected against temporary immersion, defined as 1 m for 30 minutes, not against being stored underwater. For continuous submersion the correct claim is IP68, and its depth and duration have to be stated by the manufacturer.

What does the X mean in IPX4?

The first digit was not tested or not claimed. IPX4 gives a water grade only, so it says nothing about dust. An X is not the same as a 0, which would mean the product was tested and failed to protect.

Is a higher IP rating always better?

No. A higher grade usually costs more, traps heat, and in a humid climate can increase condensation because the enclosure no longer breathes. Specify the grade the environment actually imposes.

What is the difference between IP66 and IP67?

IP66 is tested against powerful water jets, IP67 against temporary immersion. Neither substitutes for the other: a jet can force water past a seal that would survive being dunked, and standing water can find a path a jet never reaches.