Grounding Products and Systems - Elec.ru

Equipotential BondingEquipotential BondingIntroductionAlthough closely related to grounding, bonding is a distinctdiscipline that is essential to the overall facility electricalprotection scheme. Grounding provides the actual physicalconnection to earth used for establishing and maintaining itspotential, theoretically 0 volts. Bonding is the practice ofestablishing an equipotential plane by permanently joiningtogether metal parts of the wiring system as well as tyingtogether all of the electrical service grounds. Proper bondingestablishes a low impedance fault return path that allows for theproper operation of over-current devices. Additionally, bondingof all ground electrode systems (main power, telecommunications,and lightning protection) eliminates dangerous potential differencesthat can arise during fault and transient voltage conditionsjeopardizing people and equipment. Bonding of separate groundelectrode systems is required by the NFPA (The NEC ® ) as well asother international electric codes.The Importance of a Correctly Bonded Ground SystemFigure 26. Figure 27.Figure 26 shows an example of a well-designed grounding systemwith a "single point" connection of equipment power, lightningprotection, and communication ground wires to the ground-ring.If lightning hits the air terminal on the facility, the lightning protectionearth would rise equipotentially with all other ground points as theyare closely bonded together. Bonding provides little opportunity forpotential differences between ground points creating ground loops orcausing sparking or sideflashing.A non-ideal system can include multiple connection points to theground-ring and / or poor bonding connections. Figure 27 shows acase where an incoming power feed was effected by lightning.Adequate protection equipment on both power and communicationsinterface was provided, however the separate electrical andcommunications earths are located some distance apart.Figure 27. A non-ideal grounding system uses multiple connectionpoints.Regardless of how good each individual ground is, for a very shortperiod of time the potential of the electrical ground will be higherthan the communications ground. As a result the excess energy hastwo paths to follow to reach the lower potential communicationsground, thus creating a dangerous ground loop that will damage thesensitive electronic equipment in the equipment room. ERICO ®provides a number of technologies to assist in the construction ofeffective "best practice" equipotential grounding systems includingthe Transient Earth Clamp and the Insulated Joint Protector.Ph: 1-800-677-9089www.erico.com31