What "Intrinsically Safe" Actually Means
Think of an explosion as needing three ingredients in the same place at the same time: fuel, oxygen and an ignition source. You cannot easily remove flammable gas from a wellhead or combustible dust from a grain silo, and you certainly cannot remove oxygen from the air. So the only ingredient left to control is the ignition source, and a standard electronic device is a genuine candidate for that role.
A normal handheld radio uses a battery, a speaker coil and switching circuits that can, under fault conditions, produce a spark or generate enough heat to ignite a flammable atmosphere. An intrinsically safe radio is engineered from the circuit board up to limit the electrical and thermal energy it can ever release, even if a component fails, to a level too low to cause ignition. That is the whole concept in one sentence: not ruggedness, not waterproofing, but a hard energy ceiling built into the design.
This is why "rugged" and "intrinsically safe" are not interchangeable. A radio can survive being run over by a forklift and still be entirely unsuitable for a hazardous area, because intrinsic safety is about internal energy limitation, not external toughness. Do not take a supplier's word for "explosion proof" at face value. Ask for the certificate.
Intrinsic Safety Isn't the Only Protection Method
Intrinsic safety (Ex i) is the approach almost every handheld radio uses, but it's one of several recognised methods for making equipment safe in explosive atmospheres. Knowing the alternatives helps a spec sheet make sense at a glance, especially if your site also has fixed equipment like junction boxes or lighting.
| Method | How It Works | Typical Use |
|---|---|---|
| Intrinsic Safety (Ex i) | Limits electrical and thermal energy so a spark capable of ignition simply can't form, even under fault conditions | Handheld radios, sensors, portable instruments |
| Flameproof (Ex d) | Allows sparking inside a robust sealed enclosure, designed to contain any internal explosion and stop it spreading outward | Fixed equipment, junction boxes, motors |
| Increased Safety (Ex e) | Uses design and construction techniques to prevent sparks and excessive surface temperatures arising in the first place | Terminal boxes, lighting fittings, some motors |
For something a person carries, wears and operates by hand all day, intrinsic safety is almost always the practical choice. A flameproof handheld radio would need a sealed, heavy enclosure, which defeats the point of a portable device. That's why nearly every certified handheld radio on the market, regardless of brand, uses the Ex i approach.
How NZ Classifies Hazardous Areas: Zones, Groups and Temperature Class
New Zealand and Australia classify hazardous areas under AS/NZS 60079, the joint standard adapted from the International Electrotechnical Commission's IEC 60079 series. If you have ever heard someone in the US talk about "Class I, Division 1" equipment, that is a different system entirely, built around National Electrical Code rules and Nationally Recognised Testing Laboratories such as Factory Mutual. It is not the framework that applies on a New Zealand site, and equipment certified only to the American system is not automatically compliant here.
Under AS/NZS 60079, hazardous areas are split into Zones based on how often the explosive atmosphere is actually present.
| Zone | What It Means | Typical NZ Example |
|---|---|---|
| Zone 0 (gas) / 20 (dust) | Explosive atmosphere present continuously or for long periods | Inside a fuel storage tank |
| Zone 1 (gas) / 21 (dust) | Likely to occur during normal operation | Around a tanker loading gantry, inside a grain handling plant |
| Zone 2 (gas) / 22 (dust) | Not likely, and if it occurs, only briefly | The wider yard around a fuel depot or processing plant |
Beyond the zone, two other markings matter just as much. The gas group tells you which substances the equipment is rated to be near. Group IIA covers propane-type atmospheres, IIB covers ethylene, and IIC is the most demanding, covering hydrogen and acetylene. Equipment rated IIC is also acceptable for IIB and IIA sites, but the reverse is not true. The temperature class, T1 through T6, sets the maximum surface temperature the device can reach, since some hazardous mixtures will ignite well below what you'd assume is a safe surface temperature.
Equipment Protection Levels
You will also see equipment marked Ga, Gb or Gc (gas) or Da, Db or Dc (dust). These Equipment Protection Levels line up directly with the zones: Ga and Da for the highest-risk Zone 0/20 areas, down to Gc and Dc for Zone 2/22. Matching the EPL to your zone is not optional extra credit. It is the core of getting the specification right.
IECEx, ATEX and Why the US System Doesn't Apply Here
Two certification schemes matter for New Zealand buyers, and a third is worth knowing about even though it is not the local requirement.
IECEx
IECEx is the international scheme run by the International Electrotechnical Commission and is recognised across more than 30 member countries, New Zealand and Australia included. An IECEx certificate is the closest thing to a globally portable approval, which matters if your business or your equipment ever moves between here and Australia.
ATEX
ATEX is the European Union's directive covering equipment for explosive atmospheres. It is not a New Zealand legal requirement, but most reputable manufacturers certify their hazardous-area radios to both IECEx and ATEX together, since the technical requirements largely overlap. Seeing both markings on a radio is a good sign of a properly engineered product, not a red flag of irrelevance.
The US System: Class, Division and FM Approval
The United States and Canada use a different logic built around Class (I, II or III), Division (1 or 2) and Group (A through G), typically certified by a Nationally Recognised Testing Laboratory such as Factory Mutual (FM) or UL. This system predates the international IEC approach and is still the standard in North America. Some manufacturers, Tait included, certify certain radios to both frameworks so the same hardware can be sold into US and international markets. But a Class I Division 1 FM certificate on its own does not satisfy an AS/NZS 60079 requirement here, and asking a NZ supplier for that specific rating is asking for the wrong paperwork.
Choosing the Right Intrinsically Safe Radio for Your Site
Once you know your zone, gas group and temperature class, the rest of the decision comes down to matching a genuinely certified radio to your day-to-day operational needs, not just the safety rating on the box.
Tait TP9361 IS
We stock the Tait TP9361 IS across three bands: VHF (136–174MHz), UHF1 (380–470MHz) and UHF2 (450–520MHz). It is a DMR portable built on the same Tait Tough chassis as the standard TP9300 series, IP67 rated and tested well beyond MIL-STD specification, but with the internal energy limitation and IECEx/ATEX certification that make it legal for hazardous areas. It comes in the internationally recognised blue housing used to identify IS radios at a glance, supports Man Down and GPS location, and covers conventional and trunked DMR alongside analogue FM. For most Bay of Plenty and wider NZ hazardous-area users already on Tait infrastructure, this is the straightforward, verified option.
Other Certified Options
Motorola's intrinsically safe option runs through the R7-TIA range, available in VHF and UHF, paired with a certified IECEx/ATEX battery. It's worth flagging clearly: the standard MOTOTRBO R7 is a rugged, waterproof commercial radio but is not itself intrinsically safe, so if Motorola is your existing platform, specify the TIA variant fitted with the certified battery rather than assuming the standard model qualifies.
Entel's certified range runs through their ATEX-rated handhelds, including the DT985M with digital and analogue modes and a display, and the higher-power DX582M-IS at 4W. These are built and certified to marine ATEX standards, but the same certification and construction hold up equally well on an onshore hazardous site. Whichever brand you're leaning towards, insist on seeing the actual IECEx or ATEX certificate for the specific model, not just marketing language that mentions "hazardous environments."
Buying the System, Not Just the Radio
This is the part that trips up even experienced buyers. Intrinsic safety is a whole-system property. The radio, the battery, the antenna and every microphone, headset or earpiece connected to it must all carry matching certification. Fit a non-certified battery to a certified radio and you have voided the entire intrinsic safety rating, regardless of what the radio's own label says.
For accessories, we stock certified options such as the Sensear SM1P-EX headset and Tait's SAVOX HC-2 skull microphone headset for the TP9361 range, so you are matching a genuinely certified accessory to your radio rather than guessing from a generic product listing.
- Confirm the battery is specifically certified for that radio model, not just "compatible"
- Use only IS-rated speaker microphones, headsets and earpieces sold for that radio
- Never charge an IS battery inside the hazardous area itself, even with a certified charger
- Keep the whole accessory chain from the same certified range when you expand a fleet
Get the system right once, and your team has communications they can rely on in the exact environment where a dropped signal or a wrong assumption carries the highest cost.
Servicing, Accessories and the Rules That Actually Matter
An intrinsically safe radio is not a device you send to any local repair bench. Certification bodies require IS radios to be serviced only by an agency audited and approved by both the manufacturer and the relevant certification authority. Unauthorised repair, or substitution of parts that look identical but aren't the certified part number, invalidates the intrinsic safety rating on the spot, even if the radio still works perfectly.
This matters practically as much as it matters legally. A radio that has lost its IS certification through unauthorised repair looks and functions exactly like a compliant one right up until the moment it doesn't. Always confirm with your supplier where warranty and non-warranty IS servicing is actually carried out, and keep records of it. If you're buying secondhand IS equipment, ask for evidence of its service history before it goes anywhere near a hazardous area.
Who Actually Needs This
Intrinsically safe radios are a genuine requirement, not a precaution to consider, for teams working around:
- Fuel storage, tanker loading and fuel depot operations
- Oil and gas exploration, processing and pipeline sites
- Grain handling, milk powder processing and other combustible-dust environments
- Chemical storage and processing facilities
- Any confined space where flammable vapour could accumulate
If you are unsure whether your site or a specific area within it counts as hazardous under AS/NZS 60079, that classification should be documented by a suitably qualified engineer, not guessed at from a product page. Once you have that classification, choosing the right certified radio becomes a straightforward matching exercise rather than a guess.
