Older Two Prong Outlets
Grounding electrical receptacles (which some laymen refer to as outlets) is an important safety feature that has been required in new construction since 1962 because it minimizes the risk of electric shock and protects electrical equipment from damage. Modern, grounded 120-volt outlets in the United States have a small, round ground slot centered below the two vertical hot and neutral slots, providing an alternate path for electricity that can escape from the appliance. Older homes often have ungrounded two-slot outlets, which are outdated and potentially dangerous. Homeowners sometimes attempt the following dangerous modifications to ungrounded outlets:
using an adapter, also known as a "cheater". Adapters enable unearthed operation of devices that are designed for earthed operation. They are a cheaper alternative to replacing ungrounded sockets, but are less safe than properly grounding the connected appliance;
replacing a two-slot outlet with a three-slot outlet without rewiring the electrical system to provide a path to ground to the outlet. While this measure may serve as an apparently correct outlet for three-prong appliances, this "upgrade" is potentially more dangerous than using an adapter because the outlet will appear grounded and future owners may never realize their system is not grounded. If the building still uses knob and tube wiring, chances are that all three-slot outlets are ungrounded. To be sure, InterNACHI inspectors can test the grounding of suspect outlets; and
removing the earth pin from the appliance. This common procedure not only prevents grounding, but also bypasses the polarizing function of the appliance, as the unplugged plug can be inserted into the outlet in reverse.
While homeowners may be aware of the limitations of ungrounded electrical outlets, upgrades are not strictly necessary. Many small electrical appliances, such as alarm clocks and coffee makers, are two-pronged and therefore unaffected by insufficient grounding in the building's electrical system.
However, modernizing the system will bring it closer to modern security standards, which can be achieved in the following ways:
Install three-slot outlets and wire them so that they are properly grounded.
Install Ground Fault Circuit Interrupters (GFCI). These can be installed before or at the outlet itself. GFCIs are an acceptable substitute because they will protect against electric shock even in the absence of grounding, but may not protect the energized appliance. Also, ungrounded GFCI-protected outlets may not work effectively with surge protectors. Ungrounded GFCI-protected receptacles should be marked with labels supplied with new receptacles that state: "No Equipment Ground."
Replace three-slot sockets with two-slot sockets. Two-slot outlets correctly represent that the system is ungrounded, reducing the likelihood of them being misused.
Homeowners and unqualified professionals should never attempt to modify building electrical components. Improper attempts to ground containers to a metal water pipe or ground rod can be dangerous. LiteHouse Inspect inspectors may recommend that electrical outlets and wiring be evaluated by a qualified electrician.
In short, modifications should be made by qualified electricians—not homeowners—to the electrical system to upgrade ungrounded outlets to meet modern safety standards and the requirements of today's typical home appliances.