In explosive atmospheres, a single spark from poor grounding or static discharge can be enough to ignite gas or dust. Proper grounding and bonding protect personnel, ensure flameproof (Ex d) and increased safety (Ex e) integrity, and control static electricity. This guide covers what standards require and what to verify in the field.
Grounding provides a low-resistance path for fault current so protective devices trip and exposed metal does not stay live. Bonding connects metal parts to the same potential so that no voltage difference—and thus no spark—can develop between them. In hazardous locations both are mandatory: equipment must be grounded per the applicable electrical code, and metallic enclosures, conduit, cable armour, and sometimes process equipment must be bonded to prevent incentive sparks.
IEC 60079-14 and NFPA 70 (NEC) Article 501, 502, 503 specify grounding requirements for Class I/II/III and Zone installations. Use the correct conductor size and type (e.g. green/yellow, or green in North America), and ensure terminations are tight and corrosion-resistant. Loose or missing ground connections are a common audit finding.
Bonding jumpers are required where flexibility or isolation could leave metal parts at different potentials—for example between flange joints in conduit runs, across flexible couplings, or between fixed equipment and moving parts (e.g. tank trucks, loading arms). Bonding conductors should be short, robust, and sized per the applicable code so they carry fault current if needed and do not become the weak link.
In hazardous areas, static discharge can be an ignition source. Bond conductive and semiconductive parts to the plant grounding system. For non-conductive elements, consider ionization, humidity control, or conductive coatings where the risk assessment justifies it. Document bonding points and inspection frequency in the same way as other Ex installation records.
Flameproof enclosures rely on metal-to-metal flame paths. Corrosion or paint on flanges can increase contact resistance and create spark risk during fault conditions. Ensure mating surfaces are clean and that the enclosure is bonded to the grounding system so that fault current does not create arcing at the joints. Follow the manufacturer’s instructions for gland and cover bolt torque; overtightening can distort flame paths.
Correct grounding and bonding are non-negotiable in hazardous locations. If you need help reviewing installation drawings, aligning with IEC 60079-14 or NFPA 70, or preparing a grounding and bonding checklist for your site, HazloLabs can support your design and audit readiness.