What is Grounding & Bonding?

Grounding and bonding ensures that 120V circuits function properly and that accessible conductive materials in the house (pipes, faucets, slab floors on earth, and metal cases of electric appliances) cannot become a shock hazard to people, nor an electrical fire hazard to materials. Bonding maintains a zero voltage condition between all the local grounded parts within the building, as well as with the ground(s) provided by the utility on its electrical distribution system. In the occasional event of a utility ground failure, local grounding can prevent burned out electrical/electronic equipment, electrical shock or electrocution, and electrical fire that might otherwise result from an open (failed) ground connection.

PROTECTION FROM INDUCED TRANSIENT HIGH VOLTAGES FROM NEARBY LIGHTNING

Proper local grounding and bonding also enhances the discharge of induced high voltage currents from nearby lightning strikes. The better the grounding, the less likely these high-voltage induced currents are to harm electronic components connected to the building electrical system (i.e.: your computer, motors, power adapters and electronics will tend to last longer).

EQUIPMENT GROUNDING CONDUCTOR

On distribution feeder trunks and individual branch circuits, equipment grounding conductors provide a path for current to flow on in the event of a circuit fault (such as a short-circuit). The very high currents that flow on a properly-installed equipment grounding fault path are usually sufficient to trip the circuit breaker before serious damage to the circuit wiring can occur, and before heat generated due to other resistive paths in the short circuit, or arcing shorts, can generate enough heat to start a fire. Ideally, such direct shorts cleared via the equipment grounding conductor will trip the circuit breaker before any people have a chance to touch the shorted equipment and receive a shock or get electrocuted. Without this grounding conductor (or GFCI protection), equipment could become energized without tripping any breaker, waiting for some person to provide a fault-current path to earth (thereby receiving a shock, and risking electrocution for high-energy circuits). Unlike the high currents flowing on copper grounding wire to trip the circuit breaker, lethal currents flowing through resistive people will most often be too small to trip a breaker and limit the duration of the shock event.

See also:

• 2012 Cost Guide: clean up your electrical breaker panel

Related Pages

• Are your 3-prong receptacles really grounding?
• Bonding building metal piping systems
• What is a non-grounding type receptacle?
• What is Ground Fault Circuit Interrupting (GFCI)?