A bond is a permanent electrical connection between metal parts: a bonding jumper around concentric knockouts, a bonding bushing on a service conduit, or a conductor from the panel to the water and gas piping. Bonding gives fault current a low-impedance path back to the source so the breaker trips, and keeps anyone from touching two metal objects at different voltages. The main bonding jumper at the service and the system bonding jumper at a transformer are the only places neutral and ground are tied together.
Put a bonding bushing on that service conduit and jumper it to the ground bar, the concentric KOs don't count.
Grounding connects to earth; bonding connects metal to metal. Mixing the two up is the fastest way to lose an argument with an inspector.
Also heard as
- bonding jumper
- bonding
Related terms
Pigtail
Short length of wire spliced to several conductors so only one lead goes to a device terminal.
Bug
Split-bolt connector used to splice or tap heavy conductors, then wrapped in tape.
MLO
Main lugs only: a panel with no main breaker, fed through lugs from a breaker or fuse somewhere upstream.
Hot
Ungrounded, voltage-carrying conductor of a circuit, and as an adjective anything that is live.