Grounding Basics: What is Ground in Electronic Circuits

If you’re working on a circuit and you don’t know where the ground is, the first step is to consult the schematic diagram. The ground is usually (but not always) marked with a symbol that looks like a series of descending horizontal lines (see figure below).

Alternatively, if the schematic isn’t available, you can use a multimeter to identify the ground points. Set the multimeter to continuity mode and probe different points on the circuit to find a common connection to the negative terminal of the power supply. Once you locate the ground, you can proceed with your work.

What is Grounding?

Grounding, or “earthing,” refers to creating a reference point within an electrical circuit. In most cases, this reference point is considered at zero volts, acting as a common return path for electric current.

However, this can vary depending on the system in question. There are typically two types of grounding in the context of electricity: earth ground and circuit ground (common ground).

Earth Ground

Earth ground refers to a physical connection to the Earth, often through a metal rod driven into the soil. It’s different from grounding in electronic circuits or PCB design. This method is commonly used in power distribution systems, outdoor equipment, and wall outlets.

The primary function of an earth ground is safety since they operate at high voltages. It helps prevent electric shock by providing a path for fault or surge current to flow directly into the ground. This minimizes the risk of dangerous voltages on exposed conductive surfaces.

Circuit Ground (Signal Ground or Common Ground)

In electronics, ground refers to “signal ground” or “common ground”, and doesn’t need to be connected to earth.

Battery-powered devices like smartphones, laptops, or portable electronics rely on an internal circuit ground, usually tied to the negative terminal of the battery. These devices typically operate in isolation from earth ground, and their safety features are built into the design, such as in the form of protective housings or fuses.

In circuit analysis, ground is a common point that serves as the return path for current within the circuit. But in practical applications, it serves as a reference for voltage levels and ensures stable and improved circuit operation.

For example, in electronic repairs and troubleshooting, we use the ground as a reference point to measure component voltages and check for short circuits.

However, it’s important to note that not all voltage measurements use the ground as a reference point. For example, when measuring the voltage across the upper resistor in a voltage divider circuit, the reference point would not be ground.

Why is Grounding Important?

The concept of grounding is often misunderstood. It doesn’t just refer to a wire running into the earth or a convenient metal chassis—it’s the backbone of a stable and safe electrical system. Generally, grounding serves several critical purposes in electronics and electrical systems.

• Safety: Grounding helps prevent electrical shock by providing a path for excess current to flow safely into the earth in case of a fault.
• Stability: It establishes a common reference point for voltages in a circuit, ensuring stable operation and reducing noise.
• Protection: Grounding protects equipment from damage by diverting surges and spikes in electrical current away from sensitive components.

How to Ground a Circuit?

Grounding simply means establishing a connection to the ground. In circuits that are powered by a single power supply, we usually refer to the negative terminal as ground.

From the circuit below, the ground symbol is connected to every point that needs to connect to the negative terminal. This not only simplifies the circuit diagram but also makes it much cleaner and more organized, especially when there are many connections to the negative side.

In addition, when prototyping a circuit on a breadboard, you’ll typically connect the grounded leg of the components to the breadboard’s ground rail, allowing all other components to share a common reference.

Grounding is more common in digital circuits like microcontrollers (e.g., Arduino) because it provides a stable reference point for all digital signals. It is typically represented as “GND”.

In a simple setup, like with a 5V power supply, the ground pin is connected to the negative terminal of the power supply (or battery), while the positive terminal provides the power to the microcontroller. The ground pin is also an efficient return path for the current that flows from the power supply to the microcontroller.

What is Shielding (Chassis or Frame Ground)

Shielding is ideal for circuits that deal with sensitive signals, like audio or RF systems. It typically involves connecting metal enclosures or metal parts of an electronic device to the common ground of the circuit. This creates a low-impedance path for unwanted noise to return to ground rather than affecting the sensitive signal lines.

For example, in many systems, such as computers, the metal case is connected to the ground point on the motherboard to shield the internal components from electromagnetic interference (EMI).

What is a Ground Plane

In PCB (Printed Circuit Board) design, using a ground plane is a common practice. By dedicating an entire layer of the PCB to ground, you provide every component with easy access to a low-impedance ground connection. This setup helps to significantly reduce noise and improve signal integrity, which is crucial for the reliable operation of electronic circuits.

Can Grounding Save Energy?

Grounding itself does not directly save energy in the sense of reducing electricity consumption. However, it does ensure electrical systems operate as intended, free of noise and instability, which can prevent inefficiencies at some point.