Grounding + Bonding
Also known as: GroundingbondingGECEGCequipment groundmain bonding jumper
Grounding and bonding are the two related safety systems that protect you from electrical shock and protect equipment from fault currents. Grounding connects the electrical system to the earth (literal earth, via ground rods, plates, or the metal water service pipe). Bonding connects all metal parts that could become energized in a fault (panels, conduits, junction boxes, gas piping, water piping) to each other and to the grounded conductor.
The Grounding Electrode Conductor (GEC) runs from the main service panel to the grounding electrode (ground rod, water pipe, etc.). The Equipment Grounding Conductor (EGC) is the third conductor in every modern branch circuit (the bare or green wire) that bonds outlet boxes, light fixtures, and appliance frames back to the panel. The Main Bonding Jumper (MBJ) is the connection inside the main panel that bonds the neutral bus to the ground bus.
Older homes (pre-1960) often have inadequate or missing grounding. Sometimes there's a single ground rod and no GEC at all. Sometimes the GEC connects to a water pipe that's been partially replaced with plastic. K&T homes have NO equipment grounding at branch circuits. Adding grounding to an older home is usually part of a panel upgrade or whole-house rewire scope.
Grounding is invisible safety. You'll never see it work — but the moment a hot wire shorts to a metal box, the proper ground path is what trips the breaker before the box becomes lethal. We test grounding on every panel upgrade and document it (resistance measurement, electrode type, GEC routing). Documented grounding is a quiet quality signal that separates careful work from rushed work.
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