Receptacle outlets have been required to be the grounded, three-slot type since the 1962 edition of the National Electrical Code (NEC). So any new or replacement receptacle must be three-slot and a have a connection to ground from the round slot at the face, with the following exceptions for replacement of an older two-slot receptacle on a two-wire circuit (no ground available):

1) A non-grounding receptacle can be replaced with another non-grounding type (two-slot) receptacle.

2) A non-grounding receptacle can be replaced with a GFCI receptacle (three-slot), provided that a “NO EQUIPMENT GROUND” sticker is attached to the face plate.

3) A non-grounding receptacle can be replaced with a grounding type receptacle (three-slot), where the circuit is GFCI-protected at another location, such as a GFCI breaker in the panel or a GFCI receptacle upstream in the circuit. There must be a “NO EQUIPMENT GROUND” and a “GFCI PROTECTED” sticker attached to the face plate.

    All of this is per NEC 406.4(D)(2). Also, see our blog posts Is an ungrounded electric receptacle outlet dangerous? and How do you test for GFCI protection at an ungrounded receptacle outlet? and Is there an adapter that can be placed on a two-slot receptacle to make it safe? and What is a false ground, bootleg ground, or cheated ground receptacle? 

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  To learn more about electrical wiring, devices, and receptacles, see these other blog posts:

 • What is the difference between what trips a GFCI (ground fault) receptacle and a circuit breaker?

• What is the code requirement for GFCI protection for receptacles near a wet bar sink? 

• What is the requirement for a service receptacle outlet for heating, air conditioning, and refrigeration (HACR) equipment? 

• Why is an opening in the wall around the side of an electrical receptacle outlet a safety defect?  

• When was GFCI-protection for kitchen dishwasher receptacle outlet first required? 

• What is allowable voltage range at a wall receptacle outlet in a house?

• When should I replace electric receptacle outlets? 

• Does an electric receptacle outlet in a storage shed require GFCI protection? 

• What are "self-contained" electrical receptacle outlets and switches?

• What is the difference between an electrical receptacle, an outlet, and a plug?

• Does a washing machine receptacle outlet require GFCI protection?

• What is the building code requirement for receptacle outlets at stairs and stair landings?

• Can I remove a 240-volt range receptacle and hard-wire the range? 

• What is a "backstab" receptacle outlet? 

• Why are some electric receptacle outlets upside down (ground slot up) in a house?   

• What is the height requirement for an electric receptacle outlet? 

• Where are GFCI receptacle outlets required?

• When were GFCI receptacle outlets first required?

• Does a home inspector remove receptacle outlet cover plates?

• What is the minimum height for an exterior receptacle outlet? 

• How can adding wood paneling or a wainscot create an electrical safety hazard?

• How can I figure out what a mystery wall switch does?

• How far apart should kitchen counter receptacles be spaced?  

• How far above a kitchen countertop do electrical outlets have to be?

• What is reversed polarity at an outlet/receptacle? Why is it dangerous? 

• How high above the floor do electric outlets/receptacles in a garage have to be?

• How far apart should electric receptacles be spaced in a bathroom? 

• My bathroom electric receptacle/outlet is dead and there are no tripped breakers in the electric panel. What's wrong?   

• How do the new tamper-resistant electric outlets work?

• What are the most common problems/defects found with electric receptacle outlets during 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.