What is it?
Intrinsically Safe (IS) Circuit Design ensures electrical systems in hazardous areas cannot release enough energy to ignite an explosive atmosphere. Designs are carried out in compliance with IEC/BS EN 60079-11.
Who it’s for?
Design, engineering, and maintenance teams installing or upgrading equipment in hazardous zones.
Why it matters
DSEAR Regulation 7 requires equipment to be suitable for the classified zone. IEC60079-11 explains: “Intrinsic safety ‘i’ is a type of protection in which spark or thermal effect is incapable of causing ignition of an explosive atmosphere.” Poor IS design creates ignition risks and compliance failures.
How this is done
- Review of electrical design drawings and IS loop calculations.
- Verification of equipment against zone classifications.
- Advice on barriers, isolators, and wiring.
- Documentation for regulators.
- Support during commissioning.
Typical industries & processes
- Oil & Gas: refineries, offshore.
- Chemicals: bulk handling.
- Utilities: wastewater, pumping stations.
- Food & Drink: breweries, mills.
- Hydrogen production and refuelling.
Deliverables
- Verified IS design pack.
- Compliance recommendations.
Benefits
- Safe installations.
- Reduced redesign costs.
- Demonstrates compliance.
Typical timeframe
- 1–2 weeks per project phase.
Who delivers it
Our team of qualified engineers with hazardous area expertise.
Example application
We reviewed IS loop design for a hydrogen refuelling station, ensuring compliance with IEC60079-11 and IGEM/SR/25 hydrogen standards.
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Related Services
- Classroom
- Certified
- On-site
- Classroom
- Certified
- On-site
Benefits for Learners and Managers
- Foundation for safety culture: Establishes a common language and awareness of process safety across the workforce.
- Improved compliance: Supports regulatory requirements and industry standards set by the PSMCPB.
- Flexibility in delivery: Choose between direct delivery or train‑the‑trainer licensing to suit organisational needs.
- Reduced risk of incidents: Ensures staff understand their role in preventing accidents and responding effectively when things go wrong.
Course Content
- Introduction to process safety – definitions, key concepts and differentiation from occupational safety.
- Legislation and standards – overview of health and safety legislation relevant to high‑hazard industries.
- Hazard and risk identification – tools and techniques for recognising hazards and assessing risks.
- Mitigation measures and emergency response – understanding available mitigation measures and the role of emergency response.
- Consequences of process safety failures – case studies and workshop activities illustrating real-world impacts.
Key Information
Useful Information
- Service: DSEAR Risk Assessment & Hazardous Area Classification
- Standards: HSE L138, EI 15, IEC 60079-10-1 / -10-2, IEC 60079-14
- Outputs: DSEAR risk report, hazardous area classification drawings, and action plan
- Linked Regulation: DSEAR / ATEX
- Review Frequency: Every 3–5 years or following process modification
Who We Work With
- COMAH and high-hazard site operators
- Engineering and process safety teams
- Electrical, instrumentation, and control engineers
- Project and maintenance teams requiring verification and compliance
Common Triggers for Review
- Process or plant modification
- New or substituted substances
- Ventilation or containment changes
- Audit findings or equipment upgrades
- Regulatory or insurer requests
Deliverables
- Combined DSEAR and HAC report
- Zone drawings and supporting data
- Clear, traceable justification for classification decisions
- Recommendations for compliance improvement
FAQs
Intrinsic safety (IS) is a protection concept ensuring electrical equipment in hazardous areas cannot release enough energy — by spark or thermal effect — to ignite an explosive atmosphere. It is widely used in low-power control, instrumentation, and telemetry systems where continuous operation and safety are critical.
A Design Safety Document (DSD) is a formal record demonstrating that an intrinsically safe system complies with IEC/BS EN 60079-11, -14, and -25.
It compiles loop drawings, energy calculations, equipment certificates, and cable data to prove that the system remains intrinsically safe under normal and fault conditions.
DSDs are a key deliverable for verification and are routinely reviewed during DSEAR or Ex inspections.
Whenever an IS system or loop is designed, modified, or verified, a DSD should be produced or updated. It provides documented assurance that all components—barriers, isolators, field devices, and wiring—remain within certified energy limits.
Verification involves:
- Reviewingloop calculations and energy parameters.
- Checkingequipment certification for compatibility.
- Confirmingcable length and capacitance/inductance
- Ensuring segregation between IS and non-IS wiring.
Ecfio engineers can independently verify or compile DSDs to meet audit and regulatory standards.
- IEC/BS EN 60079-11– Intrinsic safety “i” protection method.
- IEC/BS EN 60079-14– Installation requirements for hazardous areas.
- IEC/BS EN 60079-25– IS system design, documentation, and verification process.
IS systems limit electrical energy at its source, preventing ignition. Explosion-proof (Ex d) systems contain any ignition within an enclosure. IS design is typically preferred for low-voltage, maintenance-accessible control systems.
Each IS circuit is cross-checked against the zone classification (Zone 0, 1, 2 / 20, 21, 22) defined in the HAC. The DSD confirms that all devices and wiring meet the protection level required for that area.
Yes. We routinely review and update legacy DSDs to ensure alignment with current standards and to close documentation gaps before inspection or audit.
- IS loop and wiring diagrams
- Equipment datasheets and Ex certificates
- Cable schedules and capacitance data
- IS system verification reports
- Maintenance and inspection records (BS EN 60079-17)
It provides a traceable record of compliance, supports modification control, and simplifies future verification. Insurers and regulators increasingly request DSDs as evidence of due diligence for hazardous area systems.
IS systems and DSDs are standard practice in:
- Oil & Gas (refineries, terminals, offshore platforms)
- Chemical manufacturing and storage
- Utilities (water, wastewater, pumping stations)
- Hydrogen production and refuelling
- Food & Drink (mills, distilleries, breweries)
Get in touch
To discuss your current DSEAR and HAC status or schedule a site review:
📧 support@ecfio.co.uk | 📞 +44 (0) [insert number]