What is Grounding?
Grounding is connecting your home’s electrical system to earth in a manner that will limit the voltage caused by lightning, line surges, or unintentional contact with higher-voltage lines, and that will stabilize the voltage to earth during normal operation.
Put another way, the purpose of grounding is to maintain a constant voltage of your home’s electrical system by dissipating voltage spikes caused by outside influences such as a lightning strike or a voltage spike on the transmission lines. The reason you don’t want voltage spikes on your home’s electrical system is because voltage spikes or surges can damage electrical equipment/components in your home.
Grounding is normally accomplished by connecting the electrical service of your home to a ground rod. This ground rod is normally an 8-foot long solid copper rod that is driven into the ground. This provides a path for any voltage spikes to travel to and dissipate into the ground.
What is Bonding?
- The purpose of bonding is using a normally non-current-carrying conductor to connect devices together to keep them at the same voltage. An example of this is swimming pool equipment which must be electrically bonded together so that all equipment such as pumps and heaters will be at the same voltage. This will prevent possible electrocution in the event that someone was touching two different pieces of pool equipment at the same time if one of those pieces of equipment happened to be at a different voltage than the other. When they are properly bonded, they cannot be at different voltages.
- In regards to our home’s electrical system, bonding is creating a path for ground-fault current to travel back to the panel in order to clear the fault. Put another way, bonding provides a path for current to flow in order to trip a breaker if there is faulty or damaged equipment plugged in. This has been called grounding for many years. Most electricians and home inspectors call it grounding, but it is NOT grounding. Grounding is what I described above. Arguments will continue over what to call it. I am not here to debate that. For the purposes of this discussion, I will call it bonding which I believe more accurately describes what is truly happening.
What is the Difference Between Grounding and Bonding?
Grounding is designed to protect your home’s electrical system and equipment from external stray voltages during normal operation.
Bonding is designed to protect people from normal voltages (and currents) when a problem exists with a piece of electrical equipment (such as the damaged refrigerator) in your home.
What is a Two-Wire System?
Can You Ground Ungrounded Outlets by Adding a Ground Rod?
How Much Current Will Flow Through a Ground Rod at 120 Volts?
Using Ohm’s law (voltage = current x resistance OR current = voltage ÷ resistance), I calculated that if I were to connect a 120-volt wire directly to my ground rod, nine amps would flow through the ground rod and into the ground (120 ÷ 13.22 = 9.08). Those nine amps would travel through that wire to the ground rod and be dissipated into the earth, and would continue to do so virtually forever. Nine amps will not cause a breaker to trip, but nine amps is much greater than the amount of current required to electrocute someone. Based on this, it should be obvious that a ground rod will not protect you from electrocution.
In summary, grounding and bonding can be confusing – especially since the terminology that has been used for years and continues to be used is confusing. Just remember that the purpose of grounding is to minimize the effect of voltage spikes caused by outside influences such as a lightning strike. The purpose of grounding is to protect equipment. Bonding on the other hand is used to clear ground faults by tripping breakers. Its purpose is to protect people.
Learn about grounded vs. ungrounded outlets.
© 2020 Mike Morgan
This article was co-written by Mike Morgan, owner of Morgan Inspection Services, and Kayla Perdue, Digital Marketing Manager. Morgan Inspection Services has been providing home, septic and well inspection services throughout the central Texas area since 2002. He can be reached at 325-998-4663 or at email@example.com. No article, or portion thereof, may be reproduced or copied without prior written consent of Mike Morgan.