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The difference between Explosion-proof & Flame-proof

One of the most common questions asked to ATEC from their clients is;

Is there a difference between ”explosion-proof” & “flame-proof “

The answer is a definite YES!

The terms “explosion-proof” or “flame-proof” are widely used in industry to describe the same equipment however technically they are not the same!

Although they perform the same function (containment) explosion-proof is US terminology, whereby “flame-proof” is regarded as IEC.

The containment approach is one of the longest used methods to protect electrical devices installed in Hazardous Areas, simply put; they contain any explosions, within that piece of equipment and prevent any ignition source or effects of the explosion from being transmitted to the exterior, potentially hazardous surroundings

Normally installations are clearly designed to IEC or NEC requirements (simply put; is it a class or zone?) But often as assets are upgraded, we often find “old” NEC equipment replaced with IEC – likely an issue provided by an inexperienced designer, creating another series of issues for the operative.


Step 1 – First we must understand the fundamental differences;


  • The term “explosion-proof” applies to hazardous location equipment products certified for use in the Class/Division system, in North America this classification system is used to describe the substance type and probability of release
  • In a Class I Division 1 location, the most common equipment protection used is explosionproof (although Intrinsically safe & pressurisation may also be acceptable)
  • Marking example; Class I, Division 1, Groups A, B, C, D; T4 (XP)
  • Certification – to Standard UL1203 for the US and 22.2-30 for Canada


  • The term “flame-proof” applies to hazardous area equipment products certified for use in line with IEC standards, based on the Zone system.
  • In a zone 1, the most common equipment protection is not always flame-proof technique, with Exe (IEC 60079-7 ) having a significant impact on the modern installation base.
  • Marking example; Ex db IIC T4 Gb
  • Certification – to IEC 60079 series of standards (Part 0 & Part 1)

Summary of main testing differences;

  • Explosion-proof is pressure tested to 4 x safety factor compared to Flame-proof 1.5
  • The IEC and UL/CSA Standards differ slightly in terms of mandated flange gaps & joint width measurements)
  • The IEC and UL/CSA Standards require a minimum wall thickness for an enclosure (no requirement in IEC)

Step 2 – Take Immediate action

ATEC staff are certified, highly skilled hazardous-area professionals who know the requirements “inside out” and are on hand to take away any confusion or mis-interpretation

We can ensure your asset is compliant and safe whilst passing on our expertise thorough cooperation during our engagement

Some examples are;

A Class I, Division 1 piece of equipment might be suitable to be installed in a Zone 1 area, but an Ex d should not be installed in a Class I Div 1 Location – ATEC can advise on the documentation trails required to prove compliance.

During Inspection & Verification programs ATEC’S approved digital ICL™ functionality assures that there is expertise, impartiality, and auditable procedures in place – digital ICL™ is the only known digitized system that provides a means of proving compliance for North American certified installations (instead of the extents of the IEC inspection tables that are not wholly appropriate for ANSI equipment).

About ATEC Services

We are a group of companies focused on services related to Hazardous Area Awareness and Asset Integrity. We provide specialized safety training and inspection services for companies who deal with the world of Potentially Explosive Atmospheres. From our inception over 11 Years ago, ATEC has without a doubt, been the go-to company for hazardous area compliance around the world.

With Office’s, Training and Inspection Centers in Houston and Singapore, the group is dedicated to the safety of personnel and asset protection by supplying International NEC / IEC Electrical Cables & Hazardous Area Accessories, Atex, IECEx competence training, including CompEx assessments, facility compliance and equipment inspection services. 

Learn more about us here!



We are pleased to officially announce the merger of EUTEX International and ATEC. Effective February 14th, 2022, both companies will operate as EUTEX International. This merger makes EUTEX the leading electrical supplier of hazardous area products and services around the globe.

The merger comes as a conjoint effort to offer the worldwide energy and renewable industry an integrated and boundary-pushing approach to working safely in hazardous areas. Our team acknowledges that our products and services impact other people’s lives, so minimizing safety risks for personnel and assets has always been our highest priority.