Ungrounded Electrical Receptacles

Grounding of electrical receptacles (which some laypeople refer to as  outlets) is an important safety feature that has been required in new  construction since 1962, as it minimizes the risk of electric shock and protects  electrical equipment from damage. Modern, grounded 120-volt receptacles in the  United States have a small, round ground slot centered below two vertical hot  and neutral slots, and it provides an alternate path for electricity that may  stray from an appliance. Older homes often have ungrounded, two-slot receptacles  that are outdated and potentially dangerous. Homeowners sometimes attempt to  perform the following dangerous modifications to ungrounded receptacles:

  • The use of an adapter, also known as a “cheater plug.” Adapters permit the  ungrounded operation of appliances that are designed for grounded operation.  These are a cheaper alternative to replacing ungrounded receptacles, but are  less safe than properly grounding the connected appliance;
  • Replacing a two-slot receptacle with a three-slot receptacle without  re-wiring the electrical system so that a path to ground is provided to the  receptacle. While this measure may serve as a seemingly proper receptacle for  three-pronged appliances, this “upgrade” is potentially more dangerous than the  use of an adapter because the receptacle will appear to be grounded and future  owners might never be aware that their system is not grounded. If a building  still uses knob-and-tube wiring, it is likely than any three-slot receptacles  are ungrounded. To be sure, InterNACHI inspectors may test suspicious  receptacles for grounding.
  • Removal of the ground pin from an appliance. This common procedure not only  prevents grounding but also bypasses the appliance’s polarizing feature, since a  de-pinned plug can be inserted into the receptacle upside-down.

While homeowners may be made aware of the limitations of ungrounded  electrical receptacles, upgrades are not necessarily required. Many small  electrical appliances, such as alarm clocks and coffee makers, are two-pronged  and are thus unaffected by a lack of grounding in the building’s electrical  system.

Upgrading the system will bring it closer to modern safety standards,  however, and this may be accomplished in the following ways:

  • Install three-slot receptacles and wire them so that they’re correctly  grounded.
  • Install ground-fault circuit interrupters (GFCIs). These can be installed  upstream or at the receptacle itself. GFCIs are an accepted replacement because  they will protect against electric shocks even in the absence of grounding, but  they may not protect the powered appliance. Also, GFCI-protected ungrounded  receptacles may not work effectively with surge protectors. Ungrounded  GFCI-protected receptacles should be identified with labels that come with the  new receptacles that state:  “No Equipment Ground.”

Homeowners and non-qualified professionals should never attempt to modify a  building’s electrical components. Misguided attempts to ground receptacles to a  metallic water line or ground rod may be dangerous. InterNACHI inspectors may  recommend that a qualified electrician evaluate electrical receptacles and  wiring.

In summary, adjustments should be made by qualified electricians — not  homeowners — to an electrical system to upgrade ungrounded receptacles to meet  modern safety standards and the requirements of today’s typical household  appliances.