This article is part 1 of 2. Part 2 covers the detailed design considerations when sealing parts of an enclosure.
Find Part 2 here: Designing IP-rated enclosures Part-2
This article explores the main design considerations when starting to develop an IP-rated enclosure. You probably have an idea of what you want to create - use the points below to challenge your design. See if you are taking the right approach, and if there’s any way to simplify the challenge.
IP rated - what does it actually mean?
IP stands for Ingress Protection. The IP rating is an IEC standard, and for a product to have an IP rating, physical lab testing must be completed on the finished product. An IP rating isn’t something you can simply design to; it always needs to be proven through testing.
The two-digit code corresponds to the level of dust and moisture protection. An “X” in place of a number indicates there is no rating for that element. Sometimes additional letter codes appear after the two digits to describe further protection levels. For example, IP69K describes an IP69 level of protection with high-temperature, high-pressure water.
Practically speaking, IP54 would be a minimum for a device used outdoors, provided it is well sheltered and raised above the ground (e.g. an outdoor light, EV charger, or electrical junction box). IP65 is more suitable for a product that is permanently installed outdoors but still mostly sheltered (e.g. a security camera, IoT sensor, or garden light). IP68 and IP69 are better suited to devices used in the rain or wet environments, with the possibility of occasional submersion (e.g. consumer tech, automotive accessories, or wristwatches).
Materials
IP-rated enclosures are most commonly made from metals or plastics. CNC aluminium or stainless steel has become a very affordable way to create a durable and reliable IP-rated enclosure, particularly in small quantities.
While plastics can be processed many ways, it’s most common to use injection moulding for IP enclosures. Most plastics can work, but typically a high-performance material such as ASA, PEEK, ABS, or PC/ABS are chosen for their stability and rigidity.
Plastic injection moulding is excellent for large production runs, but costs have come down significantly. In some cases, production runs of 100–500 units can be cheaper to injection mould than to CNC-machine, 3D-print, or vacuum cast.
3D-printing can be waterproof, but it depends on the process used. DFM is usually not waterproof unless printed very carefully. SLA 3D prints are waterproof, but are usually not well-suited for outdoor use for other reasons. MJF or SLS printing is the best bet for creating a water-tight enclosure, but consider how well a gasket or o-ring would seal on the rough, porous surface. In most cases, it would probably be advisable to avoid 3D printing for production, but take full advantage of it through the prototyping process.
Conformal Coating
The IP-rating scheme is essentially used to protect electronics. But what if the electronics don’t need protecting?
Those in the electronics engineering world will be familiar with conformal coating - a spray coating applied by PCB manufacturers after components have been soldered onto the board. This protective layer helps in multiple ways but, most importantly, makes the PCBA water-resistant.
Usually, conformal coating is used as a backup to protect the PCBA if water passes the primary seal, but in some applications, it may be all that’s needed. This is an affordable and robust approach, and something you might add to your product even if you opt for a fully sealed enclosure.
Note that the IP-rating is on the enclosure itself, so protecting the PCBA would not make it an IP-rated product.
Off-The-Shelf
By far the most cost-effective option for small-scale production and prototyping is to use an off-the-shelf IP-rated enclosure. These are readily available from electrical suppliers and can usually be purchased directly from the manufacturer for 5–10USD in quantity.
When using an enclosure like this, the main functional limitation is the cable entry points. IP-rated cable glands must be used to maintain the overall IP rating. Single wires are no issue, but with multiple wires you’ll need either multiple glands or one of the limited multi-wire types - commonly sold as solar or PV glands.
Alternatively, IP-rated connectors can be installed in the enclosure. This is useful when you have many connections (some connectors support 20+ circuits) or need to easily disconnect peripherals.
In some applications, an off-the-shelf enclosure can even be used inside a custom enclosure so that only the sensitive components are protected.
Layout choices
Wherever possible, locate all sensitive components in one area to simplify the sealing challenge. Reduce the number of penetrations, keep penetrations on the underside of the enclosure, create drip edges, and ensure there’s no pooling on a sealing edge.
While these choices are logical for keeping rain out, IP testing usually involves water jets from all directions. Moving penetrations under an overhang to protect them from vertical rain doesn’t necessarily improve the IP rating.
Always seal on a planar face where possible. This simple design decision can make a huge difference to sealing performance and complexity. It should be considered very early in the design process, often driving the entire CAD model and defining part split lines from the sealing geometry.
Screws
Screws are typically used in sealed enclosures because they apply the required compressive force on the seal and allow easy maintenance access. Consider how screw holes will be sealed early in the design. Each screw can be sealed with special washers or internally with seals or gaskets, but it’s usually best to locate screws outside the sealed area.
Thread inserts and machine screws are reliable if cost allows - consider blind thread inserts to further improve sealing performance.
Self-tapping screws are acceptable, provided the enclosure will not need to be opened. Ensure there’s enough thread engagement to provide adequate clamping force on the seal without stripping the thread.
Thread-forming screws are similar to self-tappers but are much better suited for applications where screws may need to be removed and reinserted. Thread-forming screws are engineered to reuse the existing thread, whereas self-tappers tend to cut a new one, which weakens it over time.
It’s worth noting that polycarbonate and PC/ABS materials can become brittle around self-tapping screws due to oils or residues on the screw surface reacting with the plastic. The recommended practice is to either avoid polycarbonate blends with these screw types or carefully degrease the screws before installation. Always validate with your material supplier.
Final Thoughts
Designing an IP-rated enclosure is as much about good layout and assembly choices as it is about material selection. Keep your sealing geometry simple, plan for testing, and think about how your design will perform once it leaves the lab and faces real-world weather, users, and maintenance cycles.
Whether you’re refining a concept or scaling up for production, we can help you get there faster. Reach out and let's discuss your project maxbetteridgedesign.com