Light switches have been required to be grounded since the 1999 edition of the National Electrical Code. So any light switch installed since your local AHJ (Authority Having Jurisdiction or, in other words, the building department) adopted the 1999 NEC should be grounded. Because each new edition may take several years to be adopted, it might not have gone into effect in your area until a few years later than 1999. 

Confirming grounding is easy with a tic-tracer. If you touch one of the screws on the faceplate with the tic-tracer while the switch is in the “ON” position, it will not be activated if the switch is grounded. The tic-tracer senses the electromagnetic field given off by live alternating-current wires, but the metal parts of a grounded switch will absorb the magnetic field, whereas an ungrounded switch will allow it to radiate outwards and make the tic-tracer sound off. See our blog post How does a home inspector use a tic-tracer (non-contact voltage tester) for safety when doing electrical inspections? to learn how to use one.

    The requirement for grounding is located at 404.9(B) of the NEC, and states that “snap switches, including dimmer and similar control switches, should be connected to an equipment ground conductor.” It further says that the switch "shall provide a means to connect metal faceplates to the equipment grounding conductor."

    An exception is allowed if you are replacing an exisitng switch in an older two-wire (pre-1960) electrical system that does not have a means of grounding at the box. However, an ungrounded switch must have a non-metallic faceplate that is also nonconducting and noncombustible—unless the switch mounting strap is nonmetallic or the circuit is protected by a ground-fault circuit interrupter (GFCI).

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Here’s links to a collection of our other blog posts about ELECTRICAL WIRING:

• Which house appliances need a dedicated electrical circuit?

• Can a short circuit cause a high electric bill?

• What is the maximum spacing requirement for securing NM-cable (nonmetallic-sheathed cable)?

• Is it alright to just put wire nuts on the end of unused or abandoned NM-cable or wiring?

• What causes copper wires to turn green or black in an electric panel?  

• What are typical aluminum service entrance wire/cable sizes for the electrical service to a house?

• Why is it unsafe to bond neutral and ground wiring at subpanels?

• Should I get a lightning rod system to protect my house?

• Why is a strain relief clamp necessary for the cord connection to some electric appliances?  

• Does a wire nut connection need to be wrapped with electrical tape?

• What is the minimum clearance of overhead electric service drop wires above a house roof?

• What are the requirements for NM-cables entering an electric panel box?

• What is the color code for NM cable (Romex®) sheathing?

• Why is undersize electric wiring in a house dangerous? 

• What causes flickering or blinking lights in a house?

• Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

• How can I find out the size of the electric service to a house?

• Can old electrical wiring go bad inside a wall? 

• What is an open electrical splice?

• What are the most common electrical defects found in a home inspection? 

    Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.