Grounding Metal Boxes

On 2017 06 25 by mod re.

Grounding metal boxes.

All metal boxes conduit etc used in an electrical system needs to be grounded. Don t ground to the electrical box. Most receptacles do need a ground tail. After that you need to ground the devices.

You can hit the box at one grounding screw then hit the devices from the other grounding screw. How you ground them is where it gets interesting. Equipment grounding conductor bond all metal enclosures raceways boxes and equipment grounding conductors into one electrically continuous system. If a metal box is being used best practice is to insert a green grounding screw into the threaded hole in the back of the box or enclosure.

How to ground in metal boxes in a system with metal boxes the pigtail method is considered the most secure. Connecting the ground wire to a metal electrical box will energize the box in the event of a short circuit. Lets make this real simple. You need to ground the box first and foremost.

Ground wires are spliced together and attached with a pigtail to the box and receptacle. In this video i show how a metal box is correctly grounded back to the main panel. In some installations using metal conduit the raceway the conduit boxes and connectors serve as the ground for the circuit. In this video i show how a metal box is correctly grounded back to the main panel.

Consider the installation of an equipment grounding conductor of the wire type as a supplement to a conduit only equipment grounding conductor for especially sensitive equipment. But you still would have to connect any grounding means from a light fixture receptacle etc to the back of the metal box via the pre drilled and tapped hole that is provided. Metal electrical boxes such as junction boxes metal gang boxes or metal receptacle light or ceiling fan mounting boxes all need to be connected to the system ground and of course all 120v and 220v circuit wire electrical splices must be made inside of a properly sized and rated box. Don t rely on metal sheathing or an exposed ground wire.

Metal receptacle outlet boxes must be grounded and one method is to pigtail the ground wire so that it is attached to the outlet and the metal outlet box using a green grounding screw. Metal boxes need to be connected to ground ground wire connectors for wire to wire wire to box. In this arrangement both the receptacle and metal box are grounded. As long as all the ground wires in the box are attached together and to the box.

Grounding with conduit. The box could overheat and start a fire or someone could get a shock from touching it.