Intrinsically Safe Walkie Talkies: ATEX, IECEx and UL 913 Explained

Intrinsically safe walkie talkies are designed so that, even under fault conditions, they cannot release enough electrical or thermal energy to ignite a flammable gas, vapour or dust atmosphere. Buyers usually meet three names when sourcing them: ATEX, IECEx and UL 913. These are not interchangeable labels. Each belongs to a different regulatory system, uses its own marking and is accepted in different markets.

This guide explains what intrinsic safety means, how the three schemes differ, how to read the marking on a radio and its battery, and what to check before you place an order. It is general information for buyers. The final decision on what equipment may be used in a hazardous area always rests with the site owner, its safety team and the relevant authority.

What “Intrinsically Safe” Means for a Two-Way Radio

A standard handheld radio contains a lithium battery, a transmitter and circuits that can create sparks or hot surfaces if they fail. In an area where flammable gas or combustible dust may be present, that is a potential ignition source.

Intrinsic safety (often abbreviated “IS”, or “Ex i” in international marking) is a protection concept that limits the energy available in the circuit. Designers use current-limiting resistors, voltage-limiting components, encapsulation, spacing rules and battery protection so that neither a spark nor a hot surface can reach the ignition energy or temperature of the hazardous atmosphere.

For a radio, this affects almost every part of the design:

• Battery pack: usually a dedicated, protected pack that is part of the certification. A standard battery fitted to an IS radio normally removes its IS status.
• Output power: transmit power is often lower than on the equivalent non-IS model to stay within energy limits.
• Housing and materials: materials are chosen to reduce electrostatic charge and impact risk.
• Accessories: speaker microphones, earpieces and headsets must be approved for use with that specific radio. Connecting a non-approved accessory can invalidate the protection.

Hazardous Area Classification: Zones and Divisions

Before comparing certificates, you need to know how your site is classified. There are two main systems in use worldwide.

The Zone system (IEC, ATEX and many other countries)

Areas are classified by how often an explosive atmosphere is likely to be present. For gases and vapours, Zone 0 means present continuously or for long periods, Zone 1 means likely in normal operation, and Zone 2 means not likely and only for short periods. Dust areas use Zones 20, 21 and 22 on the same logic.

The Class/Division system (North America)

The US National Electrical Code (NEC) and the Canadian Electrical Code traditionally use Classes and Divisions. Class I covers flammable gases and vapours, Class II combustible dusts and Class III ignitable fibres. Division 1 means the hazard can exist under normal operating conditions; Division 2 means it is present only under abnormal conditions. North America also recognises Zone classification for many installations.

Zone system (gas)	Zone system (dust)	Rough North American equivalent	Typical equipment protection level
Zone 0	Zone 20	Class I / II Division 1 (most severe part)	Ga / Da (e.g. Ex ia)
Zone 1	Zone 21	Class I / II Division 1	Gb / Db (e.g. Ex ib)
Zone 2	Zone 22	Class I / II Division 2	Gc / Dc (e.g. Ex ic)

The mapping above is approximate. The systems are not identical, and a radio approved for one system is not automatically approved for the other. Always check the certificate against your area classification drawing.

ATEX, IECEx and UL 913 Compared

The three schemes are often mentioned together because they cover similar technical ground, but they have different legal status and scope.

Scheme	What it is	Where it is used	What to ask for
ATEX	EU Directive 2014/34/EU on equipment for potentially explosive atmospheres, supported by harmonised EN IEC 60079 standards	European Union and countries that recognise ATEX, typically required for placing Ex equipment on the EU market	EU-type examination certificate from a notified body, EU Declaration of Conformity, ATEX marking on radio and battery
IECEx	International certification system run under the IEC, based on the IEC 60079 series	Accepted directly or as a basis for national approval in a number of countries; certificates are listed in the public IECEx online database	IECEx Certificate of Conformity number, which you can look up online, plus test and quality assessment reports if needed
UL 913	UL standard for intrinsically safe apparatus for use in Class I, II and III, Division 1 hazardous locations	United States (and referenced in North American practice); Canada uses CSA standards such as C22.2 No. 157 for intrinsic safety	Listing by a Nationally Recognized Testing Laboratory, with Class, Division and Group marking on the product

Some radios hold more than one approval, for example ATEX and IECEx together, because the test standards overlap. However, each certificate is issued for a defined model, battery and accessory combination. A certificate for one variant does not cover a similar-looking model from the same factory.

How to Read the Marking on an Intrinsically Safe Radio

The marking tells you where the radio may be used. An example of the structure of an ATEX/IECEx gas marking is “II 2G Ex ib IIC T4 Gb”. Each part has a meaning:

• II: equipment group (Group I is for mining; Group II for other surface industries with gas; dust groups are marked separately as III).
• 2G: ATEX equipment category and atmosphere type (G for gas, D for dust). Category 1 is the highest level, then 2 and 3.
• Ex ib: protection concept and level. “ia” is the highest intrinsic safety level, “ib” the next, “ic” the lowest.
• IIC: gas group. IIA covers gases such as propane, IIB includes ethylene, and IIC includes hydrogen and acetylene. IIC equipment is also suitable for IIB and IIA.
• T4: temperature class, the maximum surface temperature. T4 means 135 °C; T6 is the most restrictive at 85 °C.
• Gb: equipment protection level, which links to the zone the equipment is suitable for.

North American UL 913 marking follows a different format, typically listing Class, Division and Groups (A, B, C, D for gases; E, F, G for dusts) plus a temperature code. Read the marking on both the radio and the battery. If the two do not match the certificate, do not accept the equipment for hazardous areas.

Where Intrinsically Safe Radios Are Needed

Typical users include oil and gas production and refining, chemical and pharmaceutical plants, fuel storage and distribution, paint and coating lines, grain handling and flour milling, wastewater treatment, mining and some sections of manufacturing sites. Many of these sites also have non-hazardous areas, so fleets often mix IS radios for classified zones with standard rugged radios elsewhere.

Mixed fleets need careful control. Make IS radios visually distinct, keep IS batteries separate from standard batteries in the charging room, and train users not to swap batteries or accessories between the two groups.

Practical Buying Checks Beyond the Certificate

A certificate is necessary but not the whole picture. Buyers should also check how the radio performs and how it will be maintained.

1. Confirm the exact certified model and documentation, including the certificate number, the model code on the certificate and the approved battery and accessory list.
2. Check that the protection level, gas or dust group and temperature class match your area classification.
3. Verify the certificate in the issuing body’s database where possible, such as the IECEx online listing.
4. Review radio performance: audio loudness in high-noise areas, coverage with the reduced transmit power, and the ingress protection rating for wet or dusty sites.
5. Ask about repair policy. Many schemes require that IS equipment is repaired only by authorised facilities using approved parts, otherwise the approval may no longer apply.
6. Plan chargers and charging locations. Chargers are usually not IS-rated and must be kept in non-hazardous areas.

It is also sensible to test samples in the non-hazardous parts of your site first, following the approach in our guide on testing walkie talkie samples before a bulk order.

Accessories, Batteries and Programming for IS Radios

Accessories are where many hazardous-area fleets lose compliance. A standard remote speaker microphone or earpiece may look identical to the approved one but lack the internal components that keep the circuit safe.

Item	Common risk	Good practice
Battery pack	Standard pack fitted to IS radio	Label IS batteries clearly and store them separately
Speaker microphone	Non-approved accessory connected	Buy only accessories listed for the certified radio
Earpiece or headset	Generic audio accessory used in hazardous zone	Confirm IS approval for the specific combination
Charger	Charging inside the classified area	Charge only in non-hazardous locations
Belt clip and case	Material causes static build-up	Use cases specified by the radio maker

For standard radios in the rest of your fleet, our walkie talkie accessories range covers speaker mics, earpieces, batteries and chargers. Keep them clearly separated from the IS equipment. Channel programming, including digital features on DMR radios, should be identical across IS and non-IS radios so users can talk to each other across the site.

What to Send for a Quote/Recommendation

Hazardous-area projects move faster when the supplier receives the right information up front. Please include:

• Your hazardous area classification (Zone or Class/Division), gas or dust groups and required temperature class.
• The certification scheme you need (ATEX, IECEx, UL 913, a national scheme, or more than one) and the destination country.
• Quantity of IS radios and quantity of standard radios for non-hazardous areas.
• Frequency band, analog or digital, and your current radio models if the new units must work with them.
• Accessories needed, such as IS speaker microphones or headsets.
• Documentation requirements for your safety file and import process.

We will tell you honestly which options can meet your requirement and which cannot. Where an intrinsically safe model is proposed, we will ask you to confirm the exact certified model and documentation before ordering, so the approval matches your site and market.

Related Guides

• How Do Walkie Talkies Work
• DMR vs. Analog vs. PoC Two-Way Radios: The Ultimate B2B Sourcing Guide
• OEM & Private Label Walkie Talkie Manufacturing: A Buyer’s Guide

Frequently Asked Questions

Is an ATEX-certified radio accepted in the United States?

Not automatically. The US generally requires equipment listed by a Nationally Recognized Testing Laboratory to standards such as UL 913 for Division 1, or to US Zone standards. Some radios hold several approvals, but you must check that the specific model carries the marking your site and authority require.

What is the difference between ATEX and IECEx?

ATEX is an EU directive that makes certification a legal requirement for placing Ex equipment on the EU market. IECEx is an international certification system that uses the IEC 60079 standards. The technical tests overlap, but the certificates, marking and legal acceptance differ by country.

Can I use a standard battery in an intrinsically safe radio?

No. The battery is part of the certified design. Fitting a standard or non-approved battery usually removes the intrinsic safety protection. Use only the battery models listed on the certificate or in the manufacturer’s approved list, and keep IS batteries clearly separated from standard ones.

What does T4 mean on an Ex radio?

T4 is the temperature class. It means the maximum surface temperature of the equipment will not exceed 135 °C. The gases present at your site must have an ignition temperature above this value. T6 is the most restrictive class at 85 °C.

How do I verify an intrinsic safety certificate?

Ask for the certificate number and check it with the issuing body. IECEx certificates can be looked up in the public IECEx online database. For ATEX, request the EU-type examination certificate and Declaration of Conformity, and confirm the model code and battery listed match the radios supplied.

Talk to Us About Your Hazardous-Area Radio Requirements

If you are planning radios for a plant, terminal or processing site with classified areas, contact our team with your area classification and fleet size. We can help you structure the fleet, check what documentation to request and supply compatible standard radios and accessories for the rest of the site.