A good grounding system is essential for all building types, be it residential, commercial, or industrial. You may have heard of ground rods and water pipes used as grounding electrodes. So we researched what's the difference between them, and here is what we found.
One of the key differences between a ground rod and a water pipe is that water pipes need to be "bonded" and needs to be in contact with the earth for at least 10 feet for it to qualify to be a grounding electrode. Additionally, When using water metal pipes as an electrode, the NEC mandates that you should place at least one additional electrode.
Ground rods, on the other hand, must be at least 8 feet long, in touch with the Earth, and at least trade size 5/8 when they are rod-type electrodes and 3/4 inch when they are pipes or conduit.
Keep reading as we elaborate more on why you need an electrical grounding system and the characteristics of these grounding electrodes. We'll also cover the requirements to consider a water pipe as a grounding electrode and how to bond a water pipe so you can use it as a grounding electrode. Moreover, we'll also provide other grounding options accepted by the National Electrical Code.
Why Does Your Electrical System Need A Ground?
To safeguard both building inhabitants and equipment from the threat of excessive voltage, grounding your electrical systems is essential. A conductive surface, such as metal, can carry enough voltage to deliver a lethal shock when it is not grounded and electrically activated.
Although it receives little attention, grounding is one of the most important aspects of modern construction and equipment upkeep.
An effective grounding system guarantees that:
- Circuits feature a functional return channel that connects the power source to the device.
- Gives low resistance to trip or short circuit a breaker in the case of an electrical malfunction.
- To prevent a voltage connection from forming between metallic components, they are electrically connected.
- Establishing and maintaining a zero-voltage reference point
What Is A Ground Rod?
The grounding system of an electrical system is connected to the ground using ground rods. Although you can use many different materials to make ground rods, most homes frequently install copper.
Ground rods are excellent electrical conductors that allow any potentially hazardous voltage to flow to the ground, removing it from you and the electrical panel.
Ground rods typically need to be at least eight feet long and shouldn't be chopped down. They are occasionally piled and linked with a specific clamp to allow them to extend further into the earth in very dry ground, which offers more resistance than damp soil.
Most local governments and power providers demand the 2-ground rod approach to pass inspection. For a new building, a footing or foundation ground connection may also be permitted or necessary in some counties.
How Does A Ground Rock Work?
Ground rods protect your circuit from blowing up by providing a path for the electricity to flow back to its source.
Take lightning for example. The Earth is essentially the source of lightning. Therefore, lightning is constantly attempting to return to its Earth-based source.
When lightning strikes power lines, it will travel along the wires until it reaches the ground rods of the transformer and your main panel. It will attempt to re-enter the Earth by doing this.
Without ground rods, all of our circuits would be destroyed, and there would be home fires. Now, if the hot wire made direct contact with the ground rod, energy would flow back to the transformer through the soil, but the current would be very low due to the high resistance.
To further understand how ground rods work, you can watch this video below:
What Are The Requirements For A Water Pipe To Be Considered As Grounding Electrode?
Aside from being in direct contact with the Earth for 10 feet, here are some of the additional requirements for a water pipe to be considered as a grounding electrode:
- Electrically continuous joints.
- Don't rely on water meters to become a grounding path.
- Use bonding jumpers around any insulating pipe, joints, and meter.
- The water pipe and meter primary connection must be on the street side.
- Water pipe primary connection shall be within 5 feet of the building's entrance point.
Why The Need To "Bond" The Water Pipe?
Metal water pipe systems must be bonded back to the electrical system under Section 250.104(A) of the NEC if they are installed in or connected to a building.
The grounded conductor at the service, the grounding electrode conductor when it is big enough, the electrical service enclosure, one or more grounding electrodes for the service, or the metal water pipe can all be bonded to.
This bond's primary goal is to make sure that the service grounded conductor and the metal water pipe are both at zero voltage to the ground. A backup goal is to make sure that, if the metal water pipe electrifies, there is a way for electrical current to travel back to the service.
What Are Bonding Jumpers?
To guarantee the necessary electrical conductivity between metal components that must be electrically connected, a bonding jumper is used. It must be done in a way that will provide an efficient grounding line when connecting a grounding electrode conductor or bonding jumper to one.
Bonding must be established around insulated joints and any equipment that might need to be disconnected for repairs or replacement to guarantee the grounding channel for a metal piping system utilized as a grounding electrode.
Bonding jumpers must be long enough, usually 20 feet or longer, to let you remove the device while still maintaining the integrity of the grounding path.
What Are Other Grounding Electrodes Accepted By NEC?
The NEC specifies a list of materials that may serve as grounding electrodes and mandates their usage if any are available to create a grounding electrode system. The list of permitted grounding electrodes in Section 250.52 includes the following additional items:
Metal In-Ground Support Structure
Although the term "building steel" is frequently used to describe the metal in-ground support structure electrode, not all steel building frames fall under this category.
Direct contact with the ground or a concrete enclosure that has direct contact with the earth is required for an electrode to be considered a grounding electrode.
Often, bolts installed in the concrete foundation that is not in direct touch with the Earth's surface are used to secure steel structure frames.
Building metal frames, whether or not they are enclosed in concrete, must be at least 10 feet vertically in contact with the ground to be considered electrodes. If more than one metal piling satisfies this requirement, only one needs to be wired into the grounding electrode system.
However, nothing would impede the use of several metal in-ground electrodes as a component of the building.
This is an electrode that connects to the Earth by using the concrete structural elements of a structure.
You can create this using two methods. This electrode may be:
- unencapsulated reinforcing steel rods with a minimum diameter of 12 inches; or
- a minimum #4 AWG bare copper wire.
Either approach needs to be at least 20 feet long and covered in concrete that is at least 2 inches thick and in contact with the ground.
When reinforcing steel is what makes this electrode, it is acceptable to link several shorter rod sections together using the customary techniques, but the assembled length must be at least 20 feet long.
An encircling grounding electrode is referred to as a ground ring electrode.
This consists of a bare copper conductor with a minimum conductivity of #2 AWG and a minimum length of 20 feet. Just like the others, you must erect this type of electrode because it is not a component of the building or structure.
You can create a grounding connection using a conductive plate. You must expose a minimum of 2 ft² of the plate's surface for contact with the ground.
Given that the grounding plate has two sides in contact with the Earth, this could imply that it can be 12" × 12" in size.
The minimum thickness of the plate for uncoated iron or steel plates is 14 inches to allow for corrosion over time. Plates made of non-ferrous metal are only allowed to be 1.5 millimeters thick.
The authority having jurisdiction (AHJ) may approve the use of an electrode of a type not previously described if it is classified as a grounding electrode by a nationally renowned testing facility.
You can also use other local subsurface metal constructions and systems, like piping networks, well casings not attached to metal water lines, and underground tanks.
However, keep in mind that you can't use some systems as grounding electrodes, such as metal subterranean gas lines and the equipotential bonding grid necessary for in-ground pools. If such an item satisfies the criteria for a grounding electrode, the AHJ must decide.
Although ground rods are the more commonly known grounding electrode, you can use water pipes as one. Given that you fulfill the additional requirements for it to be one.
Should you decide to use a water pipe as your grounding electrode, you still need to add one more as mandated by the NEC. You can choose from the options mentioned above, depending on what best suits your need.
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