Hazardous Area Earthing Requirements as per International and Philippine Standards
Hazardous areas-locations with explosive atmospheres due to gases, vapors, or dust-require meticulous earthing and bonding practices to ensure electrical safety. This article outlines the requirements for hazardous area earthing per international standards and the Philippine Electrical Code ( PEC ) 2017 , including a clause-by-clause summary and a compliance checklist.
2. Objectives of Earthing in Hazardous Areas- Prevent sparking due to potential differences
- Safely discharge static electricity
- Provide a fault current return path
- Ensure lightning protection
4. Philippine Electrical Code ( PEC 2017) Clause-by-Clause Summary
Clause Title / Reference Key Requirement Rule 8.0.1.1 (Art. 500) Classification of Hazardous Areas Areas must follow NEC -type classification; electrical systems to be grounded accordingly Art. 2.50.4.3 (A) Equipment Grounding Conductor (EGC) Exposed metallic parts of equipment must be bonded to the grounding system Art. 2.50.4.5 (A) Continuity of EGC EGC shall be continuous and securely connected Art. 2.50.122 Minimum Size of EGC Ground conductor sizing based on overcurrent device rating Art. 3.0.3.10 Bonding & Grounding of Equipment Non-current carrying conductive parts (piping, vessels) must be bonded for static discharge Art. 504.50 Grounding of Intrinsically Safe Systems Intrinsically safe systems must be bonded to earth with low resistance path ( < 1 Ohm) Art. 4.20.2.4 Hazardous Locations Earthing All conductive parts of the electrical system in hazardous locations must be earthed and inspected5. Technical Implementation Requirements
Requirement Specification Ground resistance ≤ 1 Ohm (typical for Ex environments) Bonding conductor size ≥ 6 mm² copper or per PEC Table 2.50.122 Static bonding resistance ≤ 1 Ohm to earth Conductor material Copper, corrosion-resistant Lightning protection Use IEC 62305 or IEEE 998 standard design6. PEC -Based Compliance Checklist for Hazardous Area Earthing
# Requirement PEC Reference Compliant (✓/✗/N/A) Remarks 1 Hazardous area classified (Class I/II/III, Div or Zone) Rule 8.0.1.1 2 All non-current carrying metal parts bonded 2.50.4.3(A) 3 Continuity of equipment grounding verified 2.50.4.5(A) 4 Grounding conductor sized appropriately Table 2.50.122 5 Process vessels and piping bonded for static control 3.0.3.10 6 Grounding of intrinsically safe circuits provided 504.50(A) 7 Resistance to earth measured ≤ 1 Ohm 504.50(A)(2) 8 All bonding connections mechanically secure 2.50.4.3(A) 9 Lightning protection system designed & earthed Refer to IEC 62305 10 Periodic inspection and testing documented 4.20.2.47. Conclusion
The Philippine Electrical Code ( PEC 2017) integrates grounding and bonding principles aligned with international standards like IEC 60079 and NEC . For hazardous areas, strict compliance with these codes ensures personnel safety, equipment protection, and regulatory acceptance. The clause-by-clause summary and checklist provided here support engineers in ensuring full code adherence in Ex-rated installations.
See also Philippine Electrical Code - Objectionable Current
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8. Abbreviations Acronym Definition PEC Philippine Electrical Code NEC National Electrical Code (NFPA 70) IEC International Electrotechnical Commission Ex Explosion-proof EGC Equipment Grounding Conductor ATEX Atmosphères Explosibles TN-S / TT Earthing system typesLatest Posts
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