Grounding is the term loosely used to describe the built-in safety for residential electrical service.
As the electrical industry ages, the safety level improves with each passing year. Electrical Grounding is one of those improvements. Originally residential wiring was knob and tube, only 110 volts, and usually fed by a 60 amp service. Today the standard is a 200 amp 220-volt service with many larger homes requiring 300 and 400 amp services.
Unfortunately, as your house ages, the electrical system does not improve. Even worse, the demands on the system increase annually as new improved and essential appliances and electronic products fill our homes.
In the mid-1970s, the National Electrical Code (NEC) added a third wire to residential electrical wiring. Its purpose was to provide an extra level of safety. Usually, In permanent wiring, a bare grounding wire is used. A green-colored grounding wire is standard in flexible cords.
Two levels of safety exist with modern appliances. Those with metallic outer covers will have three conductors. Those with only two conductors will have non-conductive outer surfaces. The third ground wire directs stray electricity to an earth ground causing the circuit breaker to trip or fuse blow.
In addition, the current two wire receptacles and cords have one prong that is larger than the other. This ensures that the hot wire is disconnected when a switch is turned off.
A dangerous condition called “reverse polarity” exists when the house wiring is incorrectly connected to a receptacle. When reverse polarity exists, the circuit is still energized even though the switch is off.
Two of the most common deficiencies we find during a home inspection include; three-prong receptacles installed on a two-wire ungrounded circuit and reverse polarity. Both are serious safety issues and should be corrected when identified.
A qualified electrician should correct the reversed polarity by correctly connecting the wires on the receptacle. Ungrounded three-prong receptacles can be replaced with two-prong receptacles or provided with GFCI protection. A qualified electrician should also correct this.
Please note GFCI protection on a two-wire circuit does not provide Grounding. Some electronic products depend on grounding for the release of static electricity. Your electrician can help you determine where you may need the actual grounding wire.
“Arc Fault” beakers may provide additional protection. Arc fault breakers detect unusual sparking activity in the house wiring and trip the breaker when arcing is detected. Arc fault protection is required in most new homes.
These breakers may be a wise addition to protect the wiring in older homes. Check with a qualified electrician to verify if your system can be upgraded to arc fault breakers.
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