Date: September 27, 2023 9:07 am

Working in Hazardous Zone Areas

Working in Hazardous Zone Areas

The need for understanding and caution when working in hazardous areas.

A hazardous area is classified where there is a risk of an explosive atmosphere.

Hazardous areas, found in industrial settings, pose a unique set of challenges, and require specific safety measures to prevent accidents. These areas are classified into zones based on the likelihood of the presence of potentially explosive atmospheres.

The different hazardous zones are Zone 0, 1, 2, and Zone 20, 21, and 22. These zones have been established to identify to personnel the potential risk, so they can better understand and take the required safety precautions associated with each area.

There are various specifications to influence how an area is designated as a hazardous area, this is based upon flammable, explosive gasses, vapours, dust and mists being present.

What zone an area is then classified, depends upon the level of risk posed. This is based upon the frequency and duration of the occurrence of an explosive atmosphere.

The Zones classifications are 0, 1 and 2 for gas, vapour, and mist atmospheres, whereas Zones 20, 21 and 22 are based upon dust atmospheres.

Any work or installation of equipment into such areas, has strict procedures to adhere to and only professionally accredited and qualified personnel can work and sign-off installations.

With any hazardous area, some form of electrical design and installation works are required. Obviously, in such hazardous areas, the design, electrical items used, and installation layout needs to comply with the DSEAR (Dangerous Substances and Explosive Atmospheres Regulations) and BS 7671 Electrical Inspection and Testing.

The Hazardous Zones

Zones 0, 1, and 2 are classified for flammable gases, vapours, and mists.

  • Zone 0: Is the most hazardous of all the zones. It refers to an area where an explosive atmosphere is present continuously or for long periods. In Zone 0 areas, the risk of explosion is always high. As such, special equipment and strict safety protocols are necessary. Only equipment specifically designed for Zone 0 conditions should be used here. Personnel should have thorough training and adhere to strict safety procedures.
      • Can be designated as: Explosive atmosphere for more than 1000hours/year.
      • In such an environment no electrical operations or installations are possible, as a spark would cause an explosion.
  • Zone 1: An area in which an explosive atmosphere is likely to occur in normal operation. While not as dangerous as Zone 0, Zone 1 still demands vigilance. Electrical and mechanical equipment used in this zone must be designed to prevent the ignition of potentially explosive atmospheres. Workers in Zone 1 areas should be trained to recognize and respond to potential hazards.
      • Can be designated as: Explosive atmosphere for more than 10, but less than 1000hours/year.
  • Zone 2: An area in which an explosive atmosphere is not likely to occur in normal operation and, if it occurs, will only exist for a short time. Obviously, this is a less critical area, however, equipment should still meet certain safety standards. Adequate ventilation and hazard awareness are crucial for personnel working in Zone 2.
      • Can be designated as: Explosive atmosphere for less than 10hours/year.

The hazardous Zone areas 20, 21 and 22 are classified for combustible dusts.

  • Zone 20: An area in which an explosive mixture of dust is continuously present or present for long periods.
  • Zone 21: An area with a release of primary grade dust into the atmosphere. It is associated with areas where combustible dust is likely to be present in the air during normal operation.
      • Combustible dust can be ignited by sparks or high temperatures, so it’s crucial to use equipment designed to minimise these risks. Regular cleaning and maintenance of equipment are also essential in Zone 21 areas.
  • Zone 22: An area with a release of secondary grade dust into the atmosphere. It is the least hazardous of the zones concerning explosive dust atmospheres. It involves areas where combustible dust may be present but is unlikely to form a cloud in sufficient quantities to cause an explosion.
      • While the risk is lower than in other zones, safety measures should still be in place to prevent the buildup of combustible dust and the ignition of potential hazards.

Obviously, electrics are incredibility volatile in such environments and therefore requires a lighting design and any electrical control system to conform to all Hazardous Zone regulations. All electronic equipment and lighting systems must be designed to suit these requirements to prevent the possibility of any spark occurring and igniting an explosion.

Capabilities to work in Hazardous Areas

Delta Rock has the capability and appropriate qualified and accredited CompEx engineers to provide support in the design and installation of electrical and control systems for Hazardous Areas, (Zone 0, 1, 2, 20, 21 and 22), which will comply with all regulations.

We have managed and worked on a variety of projects, under Hazardous Zone Area conditions, across a range of industry sectors, including Food & Beverage, Petrochemical and Manufacturing.


Type of hazardous material

Frequency and duration of presence

0 Flammable gases, vapours, and mists

Continuously or for long periods of time

1 Flammable gases, vapours, and mists

Likely to occur in normal operation

2 Flammable gases, vapours, and mists

Unlikely to occur in normal operation, but still sufficiently likely as to require controls over ignition sources

20 Combustible dusts

Continuously or for an extended period of time or frequently

21 Combustible dusts

Frequently during normal working operations

22 Combustible dusts

Frequently during normal working operations


If you are need of the help to undertake the installation of electrical work in a Hazardous Areas, contact us now to discuss your requirements and gain the technical guidance and support of our qualified and experienced team.

It is important to note that the classification of hazardous areas is a complex process and should be carried out by a qualified professional.

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