Key takeaways
- IK and IP are independent. An IP66 cabinet can be IK07. The two codes are tested by different rigs against different physical threats, and one says nothing about the other.
- IK10 is 20 joules — a 5 kg hammer element dropped through 400 mm. IK08, the usual default, is 5 J: a quarter of the energy.
- Thickness is the expensive way to get there. Span, rib layout and edge form buy impact performance far more cheaply than a gauge up, and they do not add weight.
- The assembly is only as strong as its weakest purchased part. In our test log, windows, louvres and gland plates fail before the door skin does — roughly four times out of five.
- Impact deforms the seal path. A door that survives the blow can still lose its IP rating at the gasket, so the two certificates have to be planned together.
- Specify the target by face, not by cabinet. "IK10 on all accessible external surfaces, including the window and the vent" is a testable sentence. "Vandal resistant" is not. For what an impact rating does and does not buy you against a planned attack, see our vandal resistant enclosure design guide.
The IK rating on an enclosure datasheet is the number that decides whether a public charger survives its first year. A European operator ordered 240 pedestal chargers for on-street bays last year, specified IP65 and IK10, and signed off a 2.0 mm painted steel door with a 6 mm polycarbonate window over the display. The shell passed first time. The window cracked on the third blow. The lab report came back IK08, the whole shipment was reworked with a recessed bezel and a 10 mm laminated pane, and the delay cost eleven weeks and a launch window. The steel had never been the problem.
This guide is the impact-resistance package we now quote with every public-access enclosure. It covers what the IK code actually measures, how the IEC 62262 pendulum test is run and what "pass" really means, what each level costs you in material and weight, the six weak points that fail before the panel does, the design levers that buy joules without buying steel, and the five-step specification that keeps a programme out of rework. For the ingress side of the same box, start from our NEMA and IP ratings comparison, then the gasket sealing to IP65 guide.
What the IK Code Actually Measures
IK comes from IEC 62262 (published in Europe as EN 62262, and previously known as EN 50102), titled Degrees of protection provided by enclosures for electrical equipment against external mechanical impacts. It classifies only one thing: how much mechanical energy an enclosure surface can absorb without losing its protective function. It says nothing about dust, nothing about water, and nothing about corrosion.
The code runs from IK00 (no protection, no test) to IK10 at 20 J. The current edition also carries IK11 at 50 J, used by a handful of charger, bollard and prison-hardware programmes; not every lab has a rig tall enough for it, so confirm availability before you write it into a tender. The old third digit of the IP code — IP659, for example — was a mechanical rating and is obsolete; if you see it on a legacy drawing, translate it, do not reuse it.
| IK code | Impact energy | Equivalent drop | Typical application |
|---|---|---|---|
| IK00 | No protection | No test | Internal guards, protected plant rooms |
| IK01 | 0.14 J | 0.25 kg from 56 mm | Delicate internal bezels |
| IK02 | 0.2 J | 0.25 kg from 80 mm | Light indoor housings |
| IK03 | 0.35 J | 0.25 kg from 140 mm | Indoor control stations |
| IK04 | 0.5 J | 0.25 kg from 200 mm | Indoor wall boxes |
| IK05 | 0.7 J | 0.25 kg from 280 mm | Indoor plant-room panels |
| IK06 | 1 J | 0.5 kg from 200 mm | Sheltered industrial enclosures |
| IK07 | 2 J | 0.5 kg from 400 mm | Indoor public areas, workshops |
| IK08 | 5 J | 1.7 kg from 300 mm | Standard outdoor, fenced sites, depots |
| IK09 | 10 J | 5 kg from 200 mm | Unfenced public areas, transport hubs |
| IK10 | 20 J | 5 kg from 400 mm | Street level, vandal-exposed, EV chargers, kiosks |
| IK11 | 50 J | 10 kg from 500 mm | High-security and hostile sites (limited lab availability) |
Two practical notes on reading that table. First, the jump from IK08 to IK10 is a factor of four in energy, not a small step — which is why the material and geometry answers are so different. Second, the equivalent drop figures are derived from E = m × g × h and are what the rig physically does; they are useful for visualising the blow, but the test is defined by energy, not by mass and height.
How the Test Is Run — and Why "Pass" Is Not Cosmetic
IEC 62262 does not specify a hammer; it specifies an energy, and it references the hammer designs in IEC 60068-2-75 (test Eh). Up to IK06 the blow is delivered by a spring hammer, a hand-held spring-loaded striker with a hemispherical head. From IK07 upward it is a pendulum hammer: a steel hammer element with a hardened hemispherical striking face, swung on an arm so the drop height sets the energy. The enclosure is mounted on a rigid support in its normal service attitude, because a cabinet that is stiff in the rig and floppy on its plinth will give different results.
The test plan — how many impact points, and how many blows per point — is set from the surface area of the face under test and must be agreed with the laboratory before the sample is built. In practice labs distribute the points over the exposed surface and apply several blows at each. Points are chosen at the worst locations, not the convenient ones: door corners, the centre of the largest unsupported span, directly over a latch, and on the window or vent if one is present.
The pass criteria are the part buyers miss. After the blows, the enclosure must still:
- Protect the live parts. No deformation that reduces clearance or creepage below the required values — the probe tests of the IP code are applied afterwards, and the standard finger/probe must not reach a hazardous part. Our clearance and creepage guide sets the electrical yardstick that gets checked here.
- Hold its declared IP rating. A dented door that no longer compresses the gasket evenly fails, even though the steel did not break.
- Remain functional. The door must still open and close, the lock must still engage, and removable parts must still be removable with the intended tool.
- Keep its dielectric strength. For enclosures with an insulation function, the dielectric test is repeated after impact.
That last point is why alignment matters: a hinge that survives but twists the door 2 mm can take the IP rating with it. We cover the hardware side in the hinge and latch selection guide.
What IK10 Costs You in Metal
There is no thickness in the standard. IK is a performance test, and a well-ribbed 1.5 mm door can beat a flat 2.5 mm one. But as a starting point for quotation, these are the bands our 12-year quote log settles into for a door of roughly 600 × 800 mm with a perimeter return:
| Target | Carbon steel | Stainless 304/316L | Aluminium 5052/5754 | Shell cost vs IK08 | Weight penalty |
|---|---|---|---|---|---|
| IK07 (2 J) | 1.0–1.2 mm | 1.0 mm | 1.5 mm | Baseline | — |
| IK08 (5 J) | 1.2–1.5 mm | 1.2 mm | 2.0 mm | Reference | — |
| IK09 (10 J) | 1.5–2.0 mm + rib | 1.5 mm | 2.5 mm + rib | +5 to +12% | +15 to +25% |
| IK10 (20 J) | 2.0–2.5 mm + rib | 1.5–2.0 mm + rib | 3.0 mm + rib | +10 to +25% | +25 to +45% |
| IK11 (50 J) | 3.0 mm + frame | 2.5–3.0 mm | 4–5 mm or extrusion | +40 to +90% | +60 to +120% |
Published coupon data makes the same point more sharply. On 60 × 60 mm flat specimens struck at 20 J, measured permanent deformation runs roughly 10.6 mm on 1.0 mm 304 stainless, 7.5 mm on 1.2 mm, and 4.4 mm on 2.0 mm; aluminium deforms 11.8 mm at 1.7 mm, 9.7 mm at 2.0 mm and 0.45 mm at 3.0 mm. Flat coupons are not doors — a formed and ribbed panel behaves far better — but the shape of the curve is the lesson: doubling the thickness cuts the deformation to a third, while adding a rib can do the same for a fraction of the weight.
Material behaviour also differs. Aluminium absorbs energy by plastic deformation — it dents and keeps its seal. Stainless has higher tensile strength and scratch resistance but concentrates stress at notches and can crack rather than dent, which is why we push customers toward 5052/5754 aluminium or 304 with generous corner radii on high-energy programmes. The trade-off framework is in our material selection guide, and the joining implications in the welding guide.
The Six Weak Points That Fail Before the Panel Does
In our own test log, roughly four out of five IK failures are not the door skin. They are an accessory, an aperture or a purchased component that nobody re-rated when the IK target went up.
| Weak point | Why it fails | Fix that works |
|---|---|---|
| Display / HMI window | Polycarbonate is ductile but thin panes flex into the bezel and crack at the fastener line; glass is brittle outright | Recess the pane 6–10 mm below the door face, use 8–12 mm polycarbonate or laminated glass, add a full-perimeter bonded frame, and specify the window assembly to the same IK code as the door. See the touchscreen bezel guide |
| Vent louvres and perforations | A louvre blade is a free edge with no support behind it; perforated patterns concentrate strain at the ligament | Back perforated areas with a welded 1.5 mm perforated inner skin at 45° offset, reduce the free span of any single blade to under 80 mm, and keep the open-area target realistic — see the perforated vent pattern guide and the ventilation guide |
| Door corners | The corner is where two bend lines meet and where the door is stiffest and most brittle; a blow there levers the whole door | Weld and dress the corners instead of leaving an open notch, keep the corner radius at or above 2×t, and avoid fastener holes within 3×t of the corner |
| Hinges and latches | The door survives; the hinge leaf tears out or the latch cam jumps its strike | Specify three-point or multi-point latching above IK08, use concealed hinges, and reinforce the hinge-side return — details in the hinge and latch guide |
| Gland plate and cable entry | A thin removable plate at the bottom of the cabinet is the cheapest target on the box | Match the gland plate thickness to the door, bolt it at maximum 120 mm centres with a continuous return, and use rated glands — see the cable gland selection guide |
| Exposed external fasteners | They are an invitation, and their holes are a stress concentration | Move fasteners inside the sealed volume, use tamper-resistant drives where they must remain external, and keep the hole edge at least 3×t from any bend |
Design Levers: Stiffness Buys Joules Cheaper Than Steel
Nine geometry decisions we review at the flat-pattern stage, before anything is cut. Each one is worth more than the gauge-up it replaces.
- Shrink the unsupported span. Impact deformation scales with roughly the cube of span for a flat panel. Halving the span of a face is worth far more than adding 0.5 mm of thickness. Add an intermediate rib or move an internal divider.
- Add a perimeter return of at least 25 mm on every door and access panel. A return turns a flat plate into a shallow box section — the cheapest stiffness in sheet metal. Our stiffener rib guide gives the rib forms and spacing rules.
- Double the door skin at the strike edge with a hem or a folded-in inner panel. It puts material where the pry bar goes.
- Recess everything. A window, a keypad or a card reader set 8–10 mm below the door face is struck by the frame, not by the hammer.
- Use a continuous welded corner rather than a tab-and-slot or riveted corner on anything above IK08. The corner is a lever arm.
- Radius the corners generously. R ≥ 2t on external corners; sharp corners are crack starters on stainless and on painted high-strength steel.
- Protect the paint system. Impact that does not dent will still chip a coating at the bend; a chip is where corrosion starts. Cross-reference the powder coating versus liquid painting guide for film-build and edge-coverage choices.
- Isolate the glass. Bond glazing into a sub-frame with a continuous elastomer bead rather than clamping it with point fasteners.
- Add a sacrificial wear plate at kick height on street-level cabinets. It is cheaper to replace a bolted-on 2 mm plate than a door.
Where IK Meets IP, EMC and Certification
Impact and ingress interact, and the interaction is where programmes slip. Three rules:
- Plan the test order. A 20 J blow relaxes gasket compression and can bow a door. Sequencing that against the ingress re-test, and against every other environmental stage, is the subject of our enclosure qualification test plan guide. If one sample has to carry both certificates, agree the sequence with the lab and re-verify the seal path after the impact test; where budget allows, test IK and IP on separate samples.
- Expect to re-specify the gasket. Higher impact targets usually mean a stiffer door and more latch points, which changes compression. Work through the IP65 gasket guide again after the IK decision, not before.
- Check the certification path. For North America, remember that NEMA 250 and UL 50E do not use IK codes at all — a US spec written as "NEMA 4X, IK10" is two separate requirements from two separate schemes. Our UL 508A and IEC 61439 certification guide maps the two worlds. Where the site is also classified, the hazardous location guide governs the enclosure concept before IK is even discussed.
Product-Line Playbook
Where each of our six families typically lands, and why.
| Product line | Default IK | Driver | Notes |
|---|---|---|---|
| EV charging pedestals and pillars | IK10 | Street level, unattended, vehicle contact | See EV charger enclosure guide; window and connector holster are the weak points |
| Energy storage and power cabinets | IK08 fenced / IK10 street-level | Site access class | See energy storage cabinet guide; also check lifting and anchoring for the same cabinet |
| Industrial HMI and monitor housings | IK08–IK10 | Operator contact, tools, washdown trolleys | See HMI enclosure design guide; the bezel carries the rating |
| Telecom and network cabinets | IK10 streetside / IK08 rooftop | Public realm, refuse and bicycle contact | See telecom enclosure guide; louvre-backed vents usually govern |
| Industrial control panels | IK07–IK08 indoor, IK10 where fork trucks work | Internal traffic | See control panel guide; kick plates beat thicker doors in plants |
| Outdoor security and municipal | IK10 | Vandalism is the design case, not an accident | See outdoor waterproof guide; pair with the sunshade hood guide |
Five Steps to an IK Specification That Survives Contact
- Set the target by face and by accessory. "IK10 on all externally accessible surfaces including the display window, the vent array and the gland plate" is testable. "Vandal resistant" is not. For what an impact rating does and does not buy you against a planned attack, see our vandal resistant enclosure design guide.
- Classify the site. Street level, unfenced public realm, fenced industrial, or supervised indoor. That single answer usually fixes the code before any other input.
- Agree the test plan with the lab before the sample is built: sample mounting, number of points and blows, conditioning temperature, and the order of the IP and IK sequences.
- Design for stiffness first. Span, return depth, rib layout, recessed apertures and welded corners — then add thickness only where the numbers still say no.
- Verify, then freeze. One type test on a production-representative sample, with the window, vent and hardware from the actual bill of materials. Re-test after any change to gauge, rib layout or glazing supplier.
What the Sheet Metal Shop Does for You
Impact resistance is decided at the flat pattern, not at the test house. Send us the drawing with the target IK code and the site class, and we will return an Impact Design Pack within 24 hours: a span-and-rib review, the thickness and alloy recommendation, the window and vent detailing, the hinge and latch reinforcement, the corner and fastener layout, and a fixed-price line item for the upgrade from your current baseline. We build the test sample from production tooling and production parts, so what passes in the lab is what ships.
Use the contact form or email gongtianbao@xhlmarketing.com. If you are still at the concept stage, the sheet metal DFM guide and the prototype-to-production guide set the sequence; if you already have a rating and need it proven, our quality control and inspection guide shows how we document it.
Frequently Asked Questions
Is IK10 the same as an IP10 rating?
No, and the confusion is common. IK is mechanical impact resistance defined by IEC 62262. IP is ingress protection against solids and liquids defined by IEC 60529. They are independent: an IP66 enclosure may be IK07, and an IK10 enclosure may be IP54. Both codes are usually required on the same product and are tested on different rigs.
What material thickness do I need for IK10?
There is no thickness in the standard — IK is a performance test. As a quoting baseline for a 600 × 800 mm door with a perimeter return: 2.0–2.5 mm carbon steel with ribs, 1.5–2.0 mm stainless with ribs, or 3.0 mm aluminium. Reducing the unsupported span and adding a 25 mm return will usually get you there at the lower end of those bands.
Does the IK rating cover the window and the vents?
It should, but only if you specified it that way. The default test point selection covers the exposed enclosure surfaces, and a window, louvre or gland plate is part of the enclosure. Write the accessories into the specification explicitly, and source them to a matching IK code — in our log they are the first things to fail.
Can an enclosure lose its IP rating during the impact test?
Yes, and it is a common failure. A 20 J blow can bow a door enough to relax gasket compression at the corner, or twist a hinge so the latch no longer pulls evenly. The pass criteria require the declared IP rating to be maintained after impact, so the seal path has to be designed with the deformation in mind.
How much does going from IK08 to IK10 add to the cost?
Typically 10–25% on the shell for material, rib work, heavier hardware and reinforced apertures, plus 25–45% on weight. The larger number in a real programme is usually not the steel but the accessories: a recessed laminated glazing assembly or a backed vent array costs more than the gauge-up it replaces.