Is an IP67 enclosure the same as an explosion-proof enclosure?
Abstract
No. IP67 (IEC 60529) only means dust-tight and protected against temporary immersion in water. It is not gas-tight over time and does not contain or prevent ignition. Hazardous areas need certified Ex equipment; IP is an extra rating some Ex concepts require.
No. IP67 is an ingress protection rating under IEC 60529: the enclosure is dust-tight and keeps out harmful amounts of water during temporary immersion. It says nothing about what happens if flammable gas gets inside and meets a spark, and over months of temperature changes gas does get inside. An explosion-proof (flameproof) enclosure is designed and certified to contain an internal explosion; an IP67 box is not, unless it also carries an Ex certificate and marking.
Short answer
- IP67 = first digit 6 (dust-tight) + second digit 7 (temporary immersion, typically up to 1 m for 30 minutes). Both are tests for dust and water, not for gas or ignition.
- Explosion-proof / flameproof (Ex d) = strong enclosure plus flamepaths that cool escaping gas, tested with real internal explosions to IEC 60079-1 or UL 1203.
- A tight box is not a safe box. Gas enters slowly by breathing as the enclosure warms and cools; if it ignites inside an ordinary enclosure, the enclosure can burst or pass flame.
- IP is still required for Ex equipment, because water and dust can defeat a protection concept. Increased safety, for example, needs at least IP54 for enclosures with bare live parts (IEC 60079-7).
- Only certified equipment with an Ex marking suitable for the zone may be used. A plain IP67 enclosure is not acceptable in Zone 1 or Zone 2 as protection for sparking or hot contents.
What the IP code tests, and what it does not
The IP code describes protection of the enclosure against solid objects and water. The first digit 6 means no ingress of dust, tested in a chamber of circulating talcum powder; enclosures whose normal working cycle lowers their internal pressure, for example by thermal cycling, are tested with the inside held below atmospheric pressure. The second digit 7 means no harmful quantity of water enters during temporary immersion, for a small enclosure with its lowest point 1 m below the surface for 30 minutes. An enclosure rated 7 or 8 need not meet the water jet tests for 5 or 6 unless it is dual coded, for example IP66/IP67.
These tests are short and use dust and water. A flammable gas behaves differently: it is already mixed with air at the enclosure surface and diffuses through any seal that is not truly hermetic. Every time the contents heat up and cool down, the enclosure "breathes" a little air and gas in and out through gaskets, glands and the cable sheath. Over time the internal atmosphere can approach the outside one. The IP67 test does not look at this at all.
If that gas then meets a relay contact, a failed component or a hot surface inside, it ignites. An ordinary enclosure is not built to withstand the pressure, and its gaps are not designed to quench the flame, so the explosion can blow the lid off or ignite the surrounding atmosphere.
How IP and Ex protection fit together
| Question | IP rating (IEC 60529) | Ex protection (IEC 60079 series) |
|---|---|---|
| What it protects | The equipment, against dust and water | The atmosphere, against ignition by the equipment |
| How it is proven | Dust and water tests | Type tests to the protection concept, for example explosion tests for Ex d, energy assessment for Ex i |
| Where shown | IP67 on the label | Ex marking, for example Ex db IIC T6 Gb, plus certificate |
| Enough for a hazardous area? | No | Yes, if EPL, gas group and temperature class match the area |
The two ratings often appear side by side on Ex equipment, for example Ex db eb IIC T6 Gb IP66. The IP code then tells you how well the product resists the environment; the Ex marking tells you where it may be used.
Concepts that depend on IP. For increased safety (Ex e), IEC 60079-7 requires at least IP54 for enclosures containing bare live parts and IP44 where all live parts are insulated, because conductive dust or water could cause tracking and sparks. For dust protection by enclosure (Ex t), dust-tightness is the protection itself, with minimum IP levels in IEC 60079-31. IEC 60079-14:2024 collects the minimum IP code for each type of protection in an informative annex.
Concepts that do not. IEC 60079-1 does not make a flameproof enclosure watertight, and a flamepath is a deliberate gap. Weather protection comes from the design (for example an O-ring that is part of the certified joint) or from non-setting grease (IEC 60079-14 also allows one layer of non-hardening tape in limited cases, generally IIA only and never IIC), never from extra gaskets or sealant added on site.
Restricted breathing (Ex nR) is the one gas concept in which tightness is the protection. It is limited to Zone 2 and is proven by its own leakage test and certificate, not by an IP67 rating.
Example: A buyer is offered an "IP67 stainless steel junction box, suitable for hazardous areas" without any Ex marking. In a Zone 2 area on a solvent plant it cannot be accepted: it has no EPL Gc rating, no temperature class and no certificate. An Ex eb IIC T6 Gb IP66 junction box, or an Ex ec box for Zone 2, is the correct item, with certified Ex cable glands that maintain the IP rating.
Common mistakes
- "IP68 is better than explosion-proof." IP68 is a deeper water test; it still says nothing about ignition.
- Sealing an Ex d flamepath with silicone to reach IP67. Sealant can hold the joint open and void the certificate; see paint or seal Ex d joints.
- Losing the IP rating at installation. Wrong glands, missing seals or open entries reduce the IP rating and, for Ex e and Ex t, the protection itself.
- Assuming dust zones accept any IP6X box. Dust equipment also needs a dust EPL and a maximum surface temperature; see IP65 in Zone 21.
Related on excodex
- Ex protection concepts at a glance: d, e, i, p, m, o, q, n and t
- Flameproof enclosures (Ex d): how flamepaths stop an internal explosion
- What does IP66 on an Ex label have to do with explosion protection?
- Is an explosion-proof (Ex d) enclosure gas-tight?
- Tools: Ex marking check
Standards and further reading
- IEC 60529, degrees of protection provided by enclosures (IP code); the 1989 text with Amendment 1 as adopted in India (IS/IEC 60529:2001), with the dust and immersion tests and the dual-coding rule: archive.org
- IEC 60079-7:2015, increased safety, minimum degrees of protection IP54 and IP44: law.resource.org
- IEC 60079-1:2014, flameproof enclosures (replaced by IEC 60079-1:2026): law.resource.org
- IEC 60079-14:2024, contents including Annex P, minimum degree of protection by type of protection (public preview): standards.iteh.ai
- IEC 60079-15 (type n, restricted breathing nR) and IEC 60079-31 (dust protection by enclosure t).
This article is general technical information prepared by the excodex editorial team. It does not replace the applicable standards, the equipment certificates and instructions, national regulations or the assessment of a competent person.