Grounding & Bonding
CSI Division 26, Electrical
The system of conductors connecting a building's electrical system, equipment, and metal components to the earth, grounding, and to each other, bonding, a code-required safety system that gives fault current a deliberate, low-resistance path back to its source so a circuit breaker trips quickly instead of energizing exposed metal during a fault.
Why it matters
Grounding and bonding are what actually make overcurrent protection devices, like circuit breakers, work correctly during a ground fault, without a proper low-resistance path back to the source, a fault current might not be large enough to trip the breaker, leaving energized metal that a breaker was supposed to protect against.
On a real project
An electrician bonds a building's metal water piping, structural steel, and equipment grounding conductors all together and back to the electrical service's grounding electrode, giving any fault current a clear, low-resistance path back to the source.
Who this matters most to
An Electrician installs the grounding and bonding system, work that's inspected closely since it's essentially invisible once concealed but critical to how the rest of the electrical system actually protects people.
Where this goes wrong
An electrician misses bonding a piece of metal ductwork back to the building's grounding system during rough-in, assuming its connection to grounded structural steel elsewhere is sufficient. Months after occupancy, a maintenance worker touching that ductwork section during a minor repair gets a noticeable shock from a small ground fault upstream that never had a low-resistance path to trip the breaker, and only then does a continuity test trace the gap back to the missed bonding jumper.
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