Tag: Self-Grounding Outlets and Switches
How To Ground An Outlet
Dear Mr. Electrician: Tell me how to ground an outlet.
Answer: Learning how to ground an outlet depends significantly on your wiring methods. For instance, plastic outlet boxes have different grounding requirements than metal outlet boxes.
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Table of Contents:
HOW TO GROUND AN OUTLET WITH NON-METALLIC CABLE
GROUNDING SWITCHES AND OUTLETS WITH BX AND MC ARMORED CABLE
GROUNDING WITH METAL CONDUIT
SELF-GROUNDING SWITCHES AND OUTLETS
OTHER GROUNDING METHODS
Anything made of metal in your home that has electricity flowing through it must be grounded. Some methods below can add a ground wire when changing from a two-prong to a three-prong outlet. Photos below show how to ground an outlet or a switch under various wiring conditions.
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HOW TO GROUND AN OUTLET WITH NON-METALLIC CABLE
The uninsulated equipment grounding conductor inside the Type NM-B Non-Metallic Cable (Romex) must be connected to the grounding terminal bar at the power source, such as the main electrical panel.
The other end of the equipment grounding conductor must be connected to all metal boxes, switches, outlets, appliances, or equipment to create safer operating conditions while using electricity.
Only one wire can go under an outlet or switch's green grounding screw terminal. All other equipment grounding conductors must be spliced with a grounding pigtail wire using an approved wire connector.
Crimp sleeves are used by many electricians when working on new installations to connect all of the equipment grounding conductors together along with a pigtail. When installed correctly, the crimps are a perfect ground connection.
Wires must be twisted tightly together before crimping. I use my Klein Linesman Pliers with the built-in crimping notch to make good solid crimps, and I don't need to carry an extra tool.
The downside to crimped ground wires is that they are challenging to take apart if needed.
No code requirements exist to attach a ground wire to a non-metallic electrical box. Only metal boxes need to be grounded. However, the grounding wires in a plastic outlet or switch box should not be cut back so short that they are challenging to work with.
You must allow enough slack so that all wires in an electrical box are at least six inches (150mm) long (Article 300.14).
A metal electrical box must have a separate grounding pigtail connected to it, then connected to all the ground wires in that box. Looping the feed wire ground around the grounding screw and using the end for a pigtail connection has been disallowed, beginning with the 2020 National Electrical Code (NFPA 70) article 250.148(C).
The green twist-on wire connectors are for grounding conductors only due to the pigtail hole in the top. They are very convenient for splicing wires with a pigtail.
One grounding conductor is left much longer than the others. The shorter wire ends are twisted around the longer wire using pliers, about six inches from the long end. Then, the green wire connector is twisted...