Devices Intended for Explosion Hazard Zones

Electrical Devices Designed for Use in Explosive Atmospheres

Electrical devices designed for use in explosive atmospheres are products that incorporate construction solutions to eliminate or mitigate the possibility of igniting explosive mixtures outside these devices, both during normal operation and in fault conditions.

Electrical devices designed for use in explosive atmospheres are constructed, manufactured, tested, and marked according to the requirements of:

• Directive 94/9/EC ATEX of March 23, 1994;
• Regulation of the Minister of Economy of December 22, 2005, on essential requirements for devices and protective systems intended for use in explosive atmospheres;
• Multi-part standard EN 60079 regarding various types of construction for explosion-proof devices.

By definition, any electrically powered device—whether it uses AA/AAA batteries, 12/24V power supplies, mains power, or other sources—is capable of generating sparks that could potentially be effective sources of ignition during normal operation. Therefore, to use them in explosive zones, proper protection or construction according to the appropriate technology is necessary.

Explosion-Proof Device Construction

The construction of explosion-proof devices should ensure that the surface temperature of the enclosure and external elements is lower than the temperature of the explosive mixture in the surrounding space. Additionally, measures should be taken to prevent the formation of explosive mixtures inside the device. Explosion protection in electrical devices intended for use in the presence of gas mixtures can be achieved through:

• Protection against sparking
• Energy limitation in the circuit
• Separation of the ignition source from the explosion hazard zone
• Avoidance of flame ignition
• Use of non-flammable materials
• Temperature limitation

If an electrical device or Ex component must withstand particularly adverse working conditions—such as improper handling, moisture effects, temperature fluctuations, chemical influences, or corrosion—it is recommended that the user specifies these conditions to the manufacturer.

Special precautions should be taken if vibrations affect terminals, fuse holders, lamps, and electrical connections, potentially compromising safety, even if they meet the requirements of specific standards.

Electrical devices can only be used in hazardous locations if they meet the requirements of Annex II to Directive 1999/92/EC. In all zones, new devices must be selected based on the categories established in Directive 94/9/EC. According to explosion protection documents, working devices, including warning devices, must be designed, used, and maintained with proper attention to safety principles.

Device Groups for Ex Zones According to ATEX Directive

I – devices intended for use in mining operations where there is a methane or coal dust explosion hazard.
II – devices intended for use in locations with explosive atmospheres other than mining operations.

Device Categories

1 – a device designed to ensure a very high level of protection in atmospheres where explosion hazards are present continuously or frequently over long periods. In explosion hazard zones 0 (gases, vapors, mists) and 20 (dusts)

2 – a device designed to ensure a high level of protection in atmospheres where explosion hazards are present occasionally during normal operation. In explosion hazard zones 1 (gases, vapors, mists) and 21 (dusts)

3 – a device designed to ensure a normal level of protection in atmospheres where explosion hazards are unlikely, and if they occur, they are rare and only for short periods. In explosion hazard zones 2 (gases, vapors, mists) and 22 (dusts).

Work Atmosphere

G – device for use in explosive atmospheres created by flammable gases, vapors, mists
D – device for use in explosive atmospheres created by flammable dusts

The use of explosion-proof devices in explosive atmospheres is essential to the extent that improper construction or incorrect operation is considered one of the potential sources of effective ignition according to the PN-EN 1127-1:2011 standard. Given their widespread occurrence, this is a factor that must be strictly considered.

You should also be aware of the sources of ignition and the regulations for Ex zones. Learn more about them on our blog.