Bonding vs Earthing in Hazardous Areas: Buyer Checks

Last reviewed: September 26, 2026

Bonding vs earthing in hazardous areas: the practical difference

The OSHA Technical Manual makes the distinction in its discussion of flammable-liquid operations: bonding equalizes the potentials of connected conductive objects, while grounding provides their connection to earth. That explanation is useful beyond the vocabulary, but the manual's process examples are not universal design instructions for every installation.

For example, connecting two isolated conductive objects together does not automatically give them an earth path. The documentation should show the whole intended arrangement, including interfaces supplied or installed by others.

Define the function before choosing the hardware

Do not use the word ground as a complete engineering specification. A connection may relate to electrostatic charge control, protective earthing for electrical safety, a functional requirement or more than one purpose. Those purposes need an appropriate design basis; they are not automatically interchangeable.

A static-control lead must not be assumed suitable for carrying electrical fault current. Likewise, an electrical protective conductor does not, by its existence alone, show that every relevant process item is included in the electrostatic-control arrangement. The responsible designer must identify the functions, interactions and acceptance criteria.

Ask the supplier to identify the intended terminal or connection provision and its controlled instructions. Ask the installation designer to identify the site-side connection. A purchase description that merely requests an earth lug leaves the interface and responsibility unresolved.

Use the electrostatic guidance within its scope

The current IEC listing for IEC TS 60079-32-1:2013 with Amendment 1:2017 identifies the consolidated publication as Edition 1.1. Its scope addresses electrostatic ignition and shock hazards, including equipment, process properties and operational conditions. It describes approaches such as earthing conductors, reducing charging and limiting chargeable insulating areas.

That scope matters because adding a connection is not a universal remedy for every electrostatic hazard. A competent assessment must first identify the materials and process involved. An insulating surface, a flowing material and an isolated conductor may require different considerations.

This guide does not select resistance limits, conductor sizes, test voltages, clamp designs or operating sequences. Those decisions require the applicable licensed standards, risk assessment and installation context. A numerical limit copied from a different process can give a misleading pass result.

Prepare a connection schedule that someone can verify

A useful purchasing deliverable is a concise schedule of the connections relevant to the supplied package. This is a suggested documentation method, not a new mandatory form. Each entry should allow another competent person to identify what has been designed and what remains to be done.

1. Name both ends. Identify equipment tags or connection references rather than writing only bonded or earthed.
2. State the purpose. Record whether the connection serves static control, protective earthing, a functional requirement or a documented combination.
3. Define the boundary. Separate factory provisions, installation work and owner-supplied infrastructure.
4. Reference the design. Link the drawing, instruction and applicable revision instead of repeating an uncontrolled sketch in an email.
5. Name the verification record. Identify the inspection or test evidence required by the responsible designer and the acceptance basis.
6. Assign responsibility. State who completes the connection, who verifies it and who receives the record before use.

Use the IEC 60079-14 buyer checklist to place this schedule within the broader installation handover. A product supplier's boundary and an installation contractor's boundary should meet without leaving an undocumented gap.

Treat connection condition as an operating issue

HSE's explosive-atmospheres guidance identifies bonding conductors together and to earth as a static-control measure. It also includes monitoring static earthing and maintaining the relevant installation within the wider ignition-risk controls.

The Canadian Centre for Occupational Health and Safety discusses how dirt, paint, rust or corrosion can obstruct electrical contact in conductive-container transfer arrangements. Its example illustrates why a connection can look present without providing the intended contact. It should not be read as permission to remove a coating or alter an Ex product contrary to its controlled instructions.

For procurement, ask how the intended contact is preserved under the actual environment and use. Request the manufacturer's restrictions and the site's maintenance responsibilities. Do not substitute a photograph of an attached lead for the required verification evidence.

For recurring checks, use the separate inspection-grades guide to discuss inspection planning with the responsible professional. This article does not prescribe a universal inspection interval.

Close evidence gaps before handover

Consider a hypothetical skid purchase in which the vendor identifies a package earthing point, while the site contractor's drawing stops at a nearby structure. Neither drawing alone demonstrates the completed interface. The buyer's useful action is to request a coordinated drawing and responsibility record, not to decide that proximity proves continuity.

At handover, check whether the approved connection references appear in the completed records. Record outstanding work explicitly. If the arrangement changes, return the change to the responsible reviewer instead of carrying forward an earlier acceptance automatically.

The antistatic versus explosion-proof FAQ explains the separate equipment-evidence question. A successful continuity check does not turn an unsuitable product into explosion-protected equipment or establish compliance for an entire process.

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