Proper Ground Is ImportantPosted: January 8, 2016
By Bill Stamm.
What is Ground?
In a home electrical system, “ground” is literally the earth. Electrical equipment and receptacles are grounded to prevent personal injury and equipment damage. In modern house wiring there are three wires. One of the wires is a ground wire, which runs back to the main service panel and is connected to the earth with ground rods. If there is an electrical surge, lightning strike or damaged wires and appliances, a properly installed grounding system provides a path for stray electricity to go to ground rather than shock someone or burn up appliances. When electricity goes to ground it will usually cause circuit breakers or fuses to trip, preventing the flow of electricity to the damaged circuit.
The earth can absorb a lot of electricity and dissipates it very quickly. But in order for a ground system to work there has to be a good connection to the earth.
The ground rods are important
Ground rods are typically copper-coated steel rods that are driven into the earth and connected to a ground system with bare copper wire. To be effective it is important that ground rods are driven completely into the ground and have tight connections to the ground wires.
An important factor in how well the ground system works is what type of soil the ground rods are in. Dry sandy gravel does not conduct electricity as well as wet top soil. One benefit to the consistently wet soils in much of Alaska is that it provides good electrical conductivity when it is not frozen. Unfortunately when the soil freezes the conductivity drops off dramatically. That is why it is important to drive the ground rods all the way below the surface. It may get some of the rod below the frost layer and if you are in permafrost it will provide the most surface area for electricity to pass into the frozen soil.
Remember- when you want your electrical service to be connected to the AVEC system – an AVEC employee will ask, “Is your service properly grounded?” Your home electrical system is attached to the earth at the meterbase on the side of your house. The National Electrical Code requires a resistance to ground to be less than 25 ohms or the use of at least two ground rods, at least six feet apart.
If your service is not properly grounded the plant operator and/or travelling AVEC personnel will not hook up your service.
Electricity works without a ground
Just because the lights and appliances in your home are working it doesn’t mean they are properly grounded. For electricity to work all it needs is a complete circuit; a path to get from the power source to the appliance and a path to get from the appliance back to the source. That’s what the other two wires in modern house wiring are, typically referred to as the “hot” and the “neutral” wires.
Switches in your home and on appliances close and open the circuit made by the hot and neutral wires and turn things on and off. The ground wires are for safety and equipment protection. Electricity will take any path it can find. If electricity tries to leave the normal circuit the ground wires are there to provide a path to earth, away from you and away from appliances.
Many of today’s modern appliances, computers, refrigerator compressors, and anything with electric circuit boards, can be easily damaged by power variations. AVEC strongly recommends that consumers protect their valuable appliances with plug-in surge protection devices. Unfortunately, plug-in surge protectors cannot work without a proper ground system in the home. Make sure your ground rods are properly driven and connected, and that your receptacles are properly wired.
Older Systems and GFCI
Prior to 1962, residential wiring in the U.S. was not required to have the third grounded wire at every outlet. Since then it has been required for all new construction. The best fix for updating older systems is to install ground wires to all electrical outlets, switches and appliances, but this can be an expensive retrofit.
If you have a system with only a hot and neutral, a “quick-fix” that will provide some level of protection is to install a GFCI outlet or GFCI breaker to protect the circuit. It will not provide the same protection as a ground but it will monitor the power going out on the hot leg and back on the neutral. If the power is not the same going out and coming back the GFCI (ground fault circuit interrupter) opens the circuit to stop the flow of electricity.
GFCI’s are also required in any wet location, in bathrooms or near sinks to prevent electricity from traveling through water to ground. Even with grounded three-wire systems, water (and you) can provide another path for electricity. GFCI’s provide another level of protection by opening the circuit whenever they detect electricity has left the normal circuit.