Equipotential Bonding – Complete Overview
Equipotential bonding or simply bonding is a technique for minimising the danger of equipment damage and personal injury. It entails connecting all metals and conductive goods to an earthing system (also known as a grounding system) so that they all have the same potential energy (voltage).
Earthed materials are materials that are connected to the conductive surface of the Earth usually for the safety purpose of routing defective current into the ground (blowing a fuse) or dissipating potentially hazardous static discharges.
When numerous earthed items are connected, the magnitude of their voltages is limited, and a harmful potential difference gets avoided. This eliminates the possibility of a worker being shocked by a dangerous electric charge travelling from one earthed object through the worker and onto another earthed item of a different voltage.
When two separate things have different potential energies, it might be dangerous for a worker to come in contact with both at the same moment. This is since when a circuit is formed between two places of differing potential energy/voltage, the energy will flow as quickly as possible from the higher potential point to the lower potential one. This energy flow causes a current to flow through the worker, which, if large enough, can be fatal. The equipotential bonding of earthed equipment protects workers in equipotential zones by ensuring that the electrical potential between all the places of the body is virtually the same.
Why Equipotential Bonding?
Equipotential bonding is essentially an electrical connection that keeps the potential of several exposed and extraneous conducting elements close to the same.
An earthed equipotential zone is one in which exposed conductive parts and extraneous conducting parts are kept at nearly the same potential by bonding so that the potential
difference between simultaneously accessible exposed and extraneous conductive parts does not occur under fault situations. Bonding is the process of connecting any available metalwork to the system earth, whether it is part of the system (known as exposed metalwork) or not(known as extraneous metalwork).
Source - Lightning & Surge Technologies
Equipotential bonding is used to connect incoming water and gas supplies to the switchboard (also known as the fuse box, breaker box, or distribution board). It's also done in bathrooms, where all exposed metal (including metal pipes and electrical circuit earth) must be linked together to ensure they are always at the same potential.
What is the difference between equipotential bonding and earthing?
In its most basic form, earthing and equipotential bonding is intended to prevent electric shock.
As an example, consider a kitchen. If a dishwasher develops an electrical problem, the current is removed and sent down the earthing path of the electrical equipment. Without the earth connection, the dishwasher's metal exterior casing might become live. The goal of earthing is to keep this from happening by reducing the time that contact voltages are present.
Equipotential bonding is the use of a protective bonding conductor to connect all at-risk metallic (conductive) pieces. If you touched a malfunctioning dishwasher and then an un-bonded metal tap connected to un-bonded metal pipes in your kitchen, you may become an alternative earth path and receive a potentially fatal electric shock.
The lack of bonding (as well as earthing) would result in a chain reaction in which all metallic items in the kitchen become live. It's a frightening scenario which is why earthing and bonding are so critical, and knowing the difference between the two is crucial. The purpose of bonding is to limit the magnitude of contact voltages.
EPB vs Earthing
EPB is simply a low-resistive path to the ground that connects all metal/conductive pieces together. In an earthing system, all equipment or other current-carrying parts are connected to an earthing network. Whereas in an EPB, even non-electrical metallic equipment such as building columns, reinforcing, roofs, pipes, enclosures, gates, and so on are connected to the earthing system through a low-resistance path EPB is a component of the earthing, lightning, and surge protection systems. EPB reduces the level of touch and steps potential from an electrical standpoint.
• Grounding systems: test joint, disconnection, and potential compensation It can be placed in a register box or affixed to the wall directly.
• A potential difference can occur due to faulty equipment, such as a geezer or water cooler, which increases the potential level of pass current via pipes/faucet to increase. By connecting the pipe network to the earthing system, the potential difference can be neutralised allowing earth leakage devices to operate.
• Static charges can form in fluid-carrying pipes, mechanical equipment, and other industrial equipment, and static charges in the workplace, particularly in hazardous areas, can be extremely dangerous. One can ground them with suitable bonding.
• Assume that in one industrial shed, the bonding of metal building components (roof and cladding sheet) is not connected to other building components such as pipe racks, pipes, and so on. In the event of a lightning strike on a metal roof, the potential difference between the Metal shed and other components within the building that is close to the building envelope will be enormous. Sparking between building sheets and other equipment is a possibility in such a situation.
Industry standards certification
• Individuals working with power generating, transmission, and distribution equipment must employ equipotential bonding zones, according to OSHA standard 1910.269. The IEEE Guide for Protective Grounding of Power Lines, published by the Institute of Electrical and Electronics Engineers is one example of a method authorised by OSHA (IEEE Standard 1048).
• In the worst-case scenario, an equipotential work zone should safeguard an individual.
According to IEEE Standard 524a, an equipotential work zone is one in which all equipment is coupled by jumpers or grounding devices, resulting in an acceptable potential difference between all areas of the zone in the worst-case scenario.
Features of EPB:
• Copper bar and connecting terminals in the Cu/Zn alloy.
• Connecting 2 to 5 round conductor models.
• Valid for circular conductors with a section of 50 to 120 mm2.
• For wall mounting, the bridge is supplied with insulated connectors.
• Installation is simple.
• A secure connection is established.
Facts and Requirements of EPB:
• The purpose is to prevent indirect contact with exposed conductive parts and extraneous conductive elements that have become life due to an electric failure.
• The signalling power supply system is linked to earthed equipotential bonding within apparatus housings.
• External electrical systems are associated with equipotential bonding of extraneous conductive elements that are not within equipment housings.
• All location cases within 2.0m of each other, one of them is earthed, must be bonded together as a direct requirement. This is to avoid the possibility of a potential difference between two metal works creating a current flow if anybody mistakenly comes into contact with both cases at the same time.
• A single main earth terminal or a busbar should be provided at each point, to which the equipotential bonding should be linked where earthing systems are provided.
• Conductors for earthing and equipotential bonding should be shown on circuit diagrams and designed in such a way that they may be evaluated for effectiveness (like by provision of disconnection links).
• To protect against traction faults in AC electrified locations, equipotential bonding to the traction return system should be used. As a result, all line-side metal works should link to the traction return system rather than the real ground.
• Metalworks should avoid joining the traction return system in DC powered locations, nor should the traction return be bonded to any earth system. Since this could give an alternate return channel. These stray currents may potentially cause damage to structures.
Advantages of EPB:
• Exceptional ductility is achieved by annealing lugs and connectors.
• Ease of entry for conductors, smooth edges.
• It is economical, safe and high graded in use.
• Featuring safe and economical construction, all copper components are electro-tinned
to BS standard to prevent corrosion and oxidation.
• There are shock-proof areas for entering the wire barrel, or the entrance is bell-mouthed so the conductors can be inserted more quickly.
The equipotential standard shall be tested and marked according to the following standards and their last known amendments:
• IEC/EN 62305-3 for lightning equipotential bonding and IEC 60364-4-41/60364-5- 54 (DIN VDE 0100-410/540)
• DIN VDE 0618-1 for testing practice
• DIN VDE 0609 for testing practice
• AS/NZS 3000:2007 and AS/NZS 3000:2018 for earthing conductors and earthing arrangement practice
• NEC 250.8: Equipotential bonding for the grid
• IEC 62305
• NFC 17-102:2011
• UNE 21186:2011
• REBT- IEC 62561/1
• DIN VDE 0618-1:1989-08
• BS 7671:2018; Electrical Installations Requirements
• Main equipotential bonding according to DIN VDE 0100 and lightning protection equipotential bonding according to DIN EN 62305 equipotential bonding strip
• Code of practice for protective earthing of installations, BS 7430:2011+A1:2015
• BS IEC 60479-1:2018 IET Guidance Note 8 Earthing and Bonding Current's effects on humans and livestock.
• Underwriter Laboratories Inc. (UL): Grounding and Bonding Equipment
• Power grid corporation India limited
• NFC standards
• NTPC: National thermal power corporation
• NSIC CRISIL: SE 1A
• AEO: Indian Customs
•Star Export Hose Government of India
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