What is electrical grounding and why is it important – August 2, 2015

What is electrical grounding and why is it important – August 2, 2015

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 and 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 totally necessary appliances and electronic products fill our homes.

Ground wire was added in the 1970’s

In the mid 1970’s a third wire was added to residential electrical wiring.  It’s purpose was to provide an extra level of safety.  Usually a bare grounding wire in permanent wiring. A green colored grounding wire in flexible cords.

Two levels of safety exist with modern appliances.  Those with only two conductors will have non-conductive outer surfaces. Those with metallic outer covers will have three conductors.  The third ground wire directs stray electricity to an earth ground causing the circuit breaker to trip or fuse to blow.

In addition modern two wire receptacles and cords have one prong that is larger than the other.  This insures 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 be able to quickly 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. This should also be corrected by a qualified electrician.

GFCI Protection does not Provide Grounding

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.

Additional protection may be provided with the use of “Arc Fault” beakers.  Arc fault breakers detect unusual sparking activity in the house wiring and trip the breaker when it is detected.  Required now 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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