While most people have experienced static shocks in everyday life, few realise how dangerous they can be in ATEX Zoned environments. In these hazardous areas, the electrostatic discharge ignition risk becomes a critical safety issue, especially when flammable gases or dusts are present. Even a seemingly harmless spark can ignite a catastrophic event.
What Causes Static Discharge Ignition Risk?
Electrostatic discharge (ESD) occurs when a person or object accumulates electric charge—often from walking across low-conductivity flooring or interacting with synthetic materials. When that charged person comes into contact with a conductive surface, the charge may discharge in the form of a spark.
These sparks can carry energy up to 10 millijoules (mJ), which is significantly higher than the minimum ignition energies (MIE) of many flammable substances:
- Petrol: 0.8 mJ
- Hydrogen Gas: 0.019 mJ
- Resin Dusts: as low as 3 mJ
This makes static discharge ignition risk a serious concern in hazardous areas.
Control Measures to Mitigate Static Discharge Ignition Risk
Mitigating the static discharge ignition risk requires a combination of personal protective equipment and facility engineering.
- Static Dissipative Footwear in ATEX Zones
Personnel working in ATEX zoned areas with flammable atmospheres with a MIE of less than 10mJ should wear static dissipative footwear. These shoes safely discharge accumulated static through conductive soles. Best practices include:
- Regular on-site testing at zone entry points
- Visual inspections to ensure integrity
- Maintaining resistance to earth between 100 kΩ and 100 MΩ
- Use of Conductive or Dissipative Flooring
Flooring should also dissipate static charges. The combination of dissipative shoes and compliant flooring ensures a complete path to ground, eliminating build-up and uncontrolled discharges.
- Establishing Routine Compliance Checks
Routine testing of both footwear and flooring ensures that static control remains effective. Monitoring resistance levels helps detect early signs of equipment degradation or contamination.
Final Thoughts: Why It Matters
The static discharge ignition risk in ATEX Zoned areas is often underestimated, yet it poses a very real danger. The good news is that with proper risk assessment and reliable control measures, this hazard is entirely manageable.
Want help reviewing your site-specific electrostatic hazard controls? Contact our team today or access the official guidance on explosive atmospheres and electrostatic risks from the HSE.
Look out for Part 2: How to protect against electrostatic risks in processes, coming soon.