The purpose of bonding is to ensure the electrical continuity of the fault current path, provide the capacity and ability to conduct safely any fault current likely to be imposed, and to aid in the operation of the over-current protection device.
As discussed in the section on panel enclosures, they need to be bonded to the grounding system. But there is also a very long list of other components that need to be connected to ground, since they have the potential to become energized to electrical faults. These components include:
interior water piping;
water heaters;
around water meters;
gas lines;
electrical enclosures;
electrical raceways;
electric outlets or junction boxes;
CSST gas piping (manufacturer's compliance); and
telephone and cable TV systems.