Last updated on Nov 25, 2024

What are the differences and similarities between grounding and bonding in AC and DC systems?

Grounding and bonding are two essential concepts in electrical safety, but they are often confused or misunderstood. In this article, you will learn what grounding and bonding are, why they are important, and how they differ and resemble each other in AC and DC systems.

1 Grounding basics

Grounding is the process of connecting an electrical system or equipment to the earth or a conductive body that serves as a reference point for voltage. Grounding provides a path for unwanted or fault currents to safely dissipate, preventing shocks, fires, and damage to equipment. Grounding also stabilizes the voltage level and reduces electrical noise and interference.

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Susanta Bemal

Lead HSE Professional | ISO 45001 Lead Auditor | REC Certified Trainer | Six Sigma Green Belt | IMS | ISO 14001 | ISO 9001| ESG | CEM 1&2 | IOSH
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Grounding connects an electrical system to the earth, providing a safe path for fault currents to dissipate, preventing shocks, fires, and equipment damage. It stabilizes voltage levels and reduces electrical noise and interference, ensuring safe and efficient operation of electrical systems.

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2 Bonding basics

Bonding is the process of connecting all exposed metal parts of an electrical system or equipment to ensure electrical continuity and conductivity. Bonding creates a low-resistance path for fault currents to flow back to the source, allowing protective devices such as fuses or circuit breakers to operate and isolate the fault. Bonding also prevents potential differences between metal parts that could cause sparks, shocks, or corrosion.

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3 Grounding and bonding in AC systems

In AC systems, grounding and bonding are usually combined in a single system, called the equipment grounding conductor (EGC). The EGC connects the metal parts of the electrical equipment to the grounding electrode system (GES), which is a network of conductors and electrodes that connect to the earth. The EGC and the GES form a closed loop that carries the fault currents back to the source and provides a common reference point for voltage. The EGC also serves as a bonding conductor between the metal parts of the equipment.

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Sam Pherwani P.Eng CESCP, CUSP, MIAEI

E&I Engineer Instructor Technician, Founder Member ESIPAC, Entrepreneur - Sonsu Controls. Canadagauge. Afranfranto. Perpetual Student. Semi retired (disability)
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Bonding in AC systems, especially those where harmonic frequencies exist due to non-linear loads or power factor correction, AC skin effect is a major player on bonding conductor. The use of plate verses wire versus plate versus even foil for an inductive current carrier is to be considered for both ampacity and frequency.

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4 Grounding and bonding in DC systems

In DC systems, grounding and bonding are usually separate systems, depending on the type and configuration of the DC source. Some DC sources, such as batteries or solar panels, are inherently isolated from the earth and do not require grounding. Other DC sources, such as generators or rectifiers, may have one or more terminals grounded to the earth for safety or performance reasons. In either case, bonding is still required to connect all the metal parts of the DC equipment and ensure electrical continuity and conductivity.

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Sam Pherwani P.Eng CESCP, CUSP, MIAEI

E&I Engineer Instructor Technician, Founder Member ESIPAC, Entrepreneur - Sonsu Controls. Canadagauge. Afranfranto. Perpetual Student. Semi retired (disability)
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Grounding and bonding is performed for 2 reasons ... 1. to have a low impedance path to ground 2. to set up an equipotential zone Often times, distance between earth points causes a few volts potential difference between the two. Attempting to bond them can create a ground loop with a continuous current flow that interferes with communication and small signal devices. These situations are mitigated by isolation of signal and power ground, establishing ground grids at high fault current installations

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5 Similarities and differences

Grounding and bonding have some similarities and differences in AC and DC systems. Both grounding and bonding are intended to provide a safe and reliable electrical system by preventing shocks, fires, and damage to equipment. Both grounding and bonding require proper installation, maintenance, and testing to ensure their effectiveness and compliance with codes and standards. However, grounding and bonding also have some differences in AC and DC systems. Grounding in AC systems is usually part of the EGC, while grounding in DC systems is optional and depends on the source. Bonding in AC systems is also part of the EGC, while bonding in DC systems is a separate system. Grounding and bonding also have different effects on the voltage, current, and impedance of the electrical system.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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Luis Ortiz 🇻🇪, P.Eng.🇨🇦, P.E.🇺🇸, IntPE

Building the next generation of electrical engineers in safety, empowering future leaders, and sharing every lesson learned along the way.
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It should be considered the impact on old installations and how to deal with them in AC or DC, what the differences are, and how we can provide solutions. Grounding and bonding is an extensive subject that needs to be discussed more regularly. Any approach based on codes and standards can be different depending on the point of view of each individual doing the analysis.

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What are the differences and similarities between grounding and bonding in AC and DC systems?

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1 Grounding basics

2 Bonding basics

3 Grounding and bonding in AC systems

4 Grounding and bonding in DC systems

5 Similarities and differences

6 Here’s what else to consider

Electrical Safety

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