When you ground metal boxes in a remodel, the main goal is to make sure every metal box is electrically connected to the grounding system so that if a hot wire ever touches the box, the breaker trips instead of energizing the box. The exact method depends on the type of wiring entering the box.
If the cable includes a bare or green equipment grounding conductor, that wire should be connected to the metal box with a grounding screw or approved clip, and it should also continue on to the device or splice through to the next box if needed. In a typical box with a receptacle or switch, you usually tie the incoming ground, outgoing ground, and a short pigtail together, then land the pigtail on the green grounding screw on the device and bond the box with another short pigtail if the device itself is mounted in a metal box. That way, both the box and the device are grounded.
If the box is fed by metal conduit or armored cable that qualifies as an equipment grounding path, the box may already be grounded through the raceway, but you should not assume that automatically means every connection is solid. The fittings have to be tight and listed for the purpose. In remodel work, I’d still verify continuity rather than guessing, especially if the box is old, rusty, or has been disturbed.
A common mistake is thinking the mounting screws alone are enough. They are not a reliable ground path by themselves unless the device and box are specifically designed for that purpose and installed correctly. Another mistake is leaving the ground wire loose in the back of the box because the device “doesn’t need it.” If the box is metal, the box needs to be bonded too, not just the receptacle.
If you’re using a plastic box instead, grounding is different, because there is no metal box to bond. But with metal boxes, treat grounding as part of the box installation, not an extra step you can skip later. Also make sure the grounding screw is a proper green grounding screw, not a random wood screw or sheet metal screw.
If the box is in a kitchen, bathroom, basement, or other location with extra code requirements, it’s worth checking the specific rules that apply in your area. In older remodels, it’s also smart to test with a meter or continuity tester after everything is installed, because paint, corrosion, loose fittings, or old wiring can interrupt the ground path. When in doubt, have a licensed electrician verify it before you close up the wall.
