Grounding Vs Bonding

As the name suggests, grounding is a process to connect an electrical system to the ground. This can be termed as a safe passage for electric current. Any stray electric current in the system can safely dissipate into the ground through this passage. Following this process helps to avoid any buildup of extra current across the system and prevent risks of electrical faults. Grounding is useful in averting overcurrent situations like lightning strikes, electricity buildup or power surges.

Grounding is also helpful in case you connect faulty electrical equipment. The electric current goes straight into the earth and does not cause any shocks or fires. This is another reason why this process is popularly termed as earthing. Additionally, the process of grounding helps you to maintain stable voltage across your property.

Bonding refers to ​connecting together metal objects that do not carry current, such as metal junction boxes or gas lines. This process is necessary to prevent any potential electrical energization of these metal equipment. Even if a live wire accidentally touches any metal equipment, the bonding triggers a fuse to shut off power.

While the fuse shuts off, the current from the live wire gets directed to the electrical grounding system. This ensures that the current does not transfer from one metal equipment to the other. In the absence of bonding, such cases can develop into a hazardous situation.

The areas for grounding are specifically planned in a home’s electrical system. Grounding wires are bundled from all locations and one main grounding wire is formed. Grounding wires are either bare copper wires or green-colored wires. This grounding wire is further connected to a grounding electrode outside the home. The grounding electrode generally comes in the form of metal rods. Here are some common parts of the electrical system that need grounding:

• A main electrical panel is formed in any electrical system. This panel consists of bonded neutral wire and grounded wire.  
• In modern homes, you will find outlets with three prongs. One of these prongs connects to the grounding system.

In homes, bonding is generally done by connecting together all the metallic connectors, gas and water pipelines, metallic enclosures, any machinery equipment or exposed electronics. It is necessary to understand that bonding alone is not enough to keep the home safe. The processes of grounding and bonding work together to create a safe electrical system. Once the necessary equipment is bonded, it needs to be grounded with the help of a grounding conductor. While constructing a home, you can expect professionals to create bonding at the following locations:

• Metal water pipes 
• Metal sprinkler system
• Cables  
• Metal building frame
• Metal brackets and boxes
• Electrical raceways
• Metal gas piping
• Other metal equipment  

Article 250 of NEC directs that all AC systems of 50 to 1000 Volts must be grounded. It further outlines the type of grounding electrodes and grounding systems that should be used.

• NEC section 250.50 mandates all grounding electrodes to be bonded together. These can include grounding rods, metal water pipes and building steel. 
• The electrical service must be grounded where it enters the building. A grounding electrode conductor (GEC) is used to connect back electrodes to the building’s electrical service.
• The basic grounded systems included in NEC are electrical system grounding, electrical equipment grounding, electrical equipment bonding and bonding of conductive materials.

Article 2500 of the NEC delivers key requirements for bonding. This is necessary because bonding complements the process of grounding to decrease the risk of electrical shocks and fires.

• While bonding metal piping, such as water or gas pipes, you must bond jumpers across the piping. This will keep the whole piping system from carrying any electrical current.
• In section 250.28, NEC mandates the use of a main bonding jumper. This further ensures that any metal enclosure is bonded to the electrical grounding system.
• As per NEC, bonding is necessary to eliminate any difference in the potential of metal equipment. In case this happens, current will flow from one metal equipment to another. Bonding keeps the potential of all metal equipment the same and, hence, prevents any current flow between them.