How To Ground an Ungrounded Outlet

Improve electrical safety in your home by grounding or replacing old two-prong ungrounded outlets.

If your home was built before the 1960s, you might still have some old two-prong ungrounded outlets. The correct name for an ungrounded outlet is a non-grounding-type receptacle. So here, we’ll use that term.

Non-grounding-type receptacles are called that because they lack a third prong for grounding electrical equipment, appliances and tools. Grounding is important to protect against electric shocks; the third line redirects electric current during a hazardous ground-fault condition in an appliance.

Attempting to plug three-prong appliance and equipment cords into old two-prong receptacles can be a serious electrical hazard and probably violates the manufacturer’s warranty.

The National Electrical Code (NEC) generally does not apply retroactively, so you’re not obligated to replace non-grounding-type receptacles. However, if you do replace them, the new ones must be grounded to conform to the NEC.

Replacing old receptacles used to be simple. But now, like many things, it’s more complicated. The good news is, there are multiple viable options.

Grounding-Type Receptacle Replacement

Where a grounding means exists in the receptacle box, three-prong grounding-type receptacles must be installed as replacements. The green grounding terminal on the receptacle must be connected to the grounding means. The grounding means might be a grounded metal box, or a bare or green copper equipment grounding wire in the box.

With some basic testing, you should be able to determine if a grounding means exists.

Non-Grounding-Type Receptacle Replacement

Where a grounding means does NOT exist in the receptacle box, you have a few options:

Replace with another non-grounding-type receptacle

  • Non-grounding-type receptacles are still manufactured in limited quantities, so you can replace a broken one with a new one. It doesn’t enhance electrical safety, but allows you to make a necessary repair in a pinch.
  • Don’t use three-prong adapters with two-prong plugs. If not installed properly, they can be a serious safety hazard.

Replace with a ground-fault circuit-interrupter (GFCI) receptacle

  • This significantly improves safety. You won’t have a grounding means for your appliances, but the GFCI provides shock protection by tripping and stopping the flow of electricity during a ground-fault condition.
  • If you select this option, the receptacle or cover plate must be labeled “No Equipment Ground.” The labels are included in the package when you buy the GFCI receptacle.

Replace with a grounding-type receptacle

  • If you have a branch circuit with a series of daisy-chained receptacles around a room, you can install a GFCI receptacle in the first receptacle box as mentioned above, then install standard grounding-type receptacles in the downstream receptacle boxes. Say you have a branch circuit that supplies four receptacles in one bedroom, then it jumps over to supply four receptacles in another bedroom. You only need one GFCI in the first receptacle box on that circuit in the first bedroom, and seven standard receptacles in the remaining downstream boxes on that circuit.
  • The GFCI receptacle must be labeled “No Equipment Ground,” and the other downstream standard grounding-type receptacles or their cover plates must be labeled “GFCI Protected” and “No Equipment Ground.” These labels are provided by the manufacturer when you buy the GFCI receptacle.

Are There Other Code Requirements When Replacing Receptacles?

In recent years, the NEC added new rules for replacement receptacles. These are applicable to any type of existing receptacle you replace, two-prong or three-prong.

Ground-fault circuit-interrupter protection (GFCI)

GFCI technology protects people from lethal shocks. If you replace an existing two-prong or three-prong receptacle at a location that must otherwise have GFCI protection in the current NEC — say, next to your bathroom sink — you need to provide GFCI protection.

Arc-fault circuit-interrupter protection (AFCI)

AFCI technology protects people and property from fire hazards. If you replace an existing two- or three-prong receptacle at a location that must otherwise have AFCI protection in the current NEC, like in a bedroom model, you need to provide AFCI protection. Best to install an AFCI circuit breaker at your main panel.

Tamper-resistant receptacles (TR)

A tamper-resistant receptacle has built-in shutters to prevent young children from inserting foreign objects into the receptacle. When replacing existing receptacle outlets, all replacement receptacles must be tamper-resistant.

Weather-resistant receptacles (WR)

Weather-resistant receptacles feature corrosion-resistant components. When properly installed in a weatherproof enclosure, they provide extra durable protection from rain, snow, ice and moisture.

If you replace an existing receptacle at a location that otherwise requires weather-resistant receptacles in the current NEC, the replacement receptacles must be weather-resistant. So if you replace an old outdoor GFCI receptacle, then the replacement GFCI receptacle needs to be marked WR.

John Williamson
John Williamson has been in the electrical industry in Minnesota for over 45 years as an electrician, inspector, instructor and administrator. John is a licensed master electrician and certified building official. John has worked in the construction codes, licensing and inspection industry for over 33 years, with over 27 years at the State of Minnesota. For the past 30 years John has also provided electrical code consultation and writing for various book and magazine publishers. John is retired from the Minnesota Department of Labor and Industry where he was the Chief Electrical Inspector.