Neutral and Ground are two important conductors in AC Electrical Systems. Most people often confuse between them as they are essentially connected to the same bus bar in the main circuit breaker panel. Even though Ground and Neutral wires are closely related, they are not the same. We will understand the difference between ground vs neutral, learn the importance of each wire in a typical residential AC Electrical System.
We already discussed a little bit about grounding and different types of grounding in a previous guide. Check that for more info on grounding.
A Brief Guide on Electricity Distribution
We can divide the electric power system into a) Generation b) Transmission and c) Distribution. Generation stage consists of generating Electric Power at the power plants (power stations, generating stations, etc.). These are usually located far from urban population or near the resources such as dams (for hydroelectric power) or near coal mines (thermal electric power).
After electricity is generated at the power plant, it travels hundreds of kilometers using a vast network of transmission lines and reaches local substations. From these substations, it is supplied to our street transformers (known as distribution transformers), which then step down the voltage to a safe level (either 120V or 230 – 240V, depending on where you live).
From these transformers, we get the hot, neutral and ground wires to our homes.
Importance of Neutral
For electric current to flow, an electric circuit must be a closed loop between the source and the load. In a typical residential electrical wiring, electric current flows through the “hot” wire to the load (an electrical appliance or device) and returns to the source (which is the distribution transformer in this case) through the neutral wire.
So, Neutral is a current carrying conductor that acts as a return path for the current in AC circuit. Physically, neutral wire is taken from the center tap of the secondary of the transformer, which is usually in a Star (or WYE formation).
The main reason for the confusion between Ground vs Neutral is because, the Neutral Wire is connected to Ground (Earth) at the transformer (which is the source) and also at the main circuit breaker panel on the consumer side (which is the load). The reason for this connection is to make the Neutral wire the same potential as Earth, which is zero.
Importance of Ground
Ground or Earth is a safety mechanism to divert the current in case of an accidental contact of hot wire to any metal part. The Ground wire acts as a low impedance path for faulty currents to flow to ground. Hence, every house must have a ground wire connected to a ground rod.
Usually, we connect this ground wire to the ground bus in the main circuit breaker panel. From this panel, we supply the ground wire to all individual branch circuits and is connected to the metal parts of appliances, metal pipes, receptacle boxes and other metal conductors that are not supposed to carry current.
An important point to note here is that at the main service panel, the neutral bus bar and the ground bus bar are bonded together so that neutral is referenced to earth.
Back to the ground wire, it is normally not a current carrying wire. But if the hot wire makes contact with the metal frame of an appliance due to some accident, the current flows through the ground wire to the ground (earth) and avoid electrical shock by tripping the circuit breaker.
If the ground wire is absent and if we contact the metal part/frame of the appliance, then the current flows from the hot wire flows through the metal body, then through your body and finally to ground. This causes a severe electrical shock to us and could be fatal.
Differences: Ground vs Neutral
Let us now see the differences between Ground and Neutral wires.
|It is normally a current carrying conductor.
|Normally, it is not a current carrying conductor.
|Neutral acts as a return path for current to flow from load (appliance) to source (transformer).
|Ground acts as a low resistance path for fault current to flow to ground.
|It is usually White or Grey in color.
|It is usually Green or Yellow – Green in color for conduit wiring or just bare copper wire.
|Neutral originates from the star point of the secondary of the distribution transformer which is in a Wye or Star configuration.
|We insert a ground rod near our house into earth and connect Ground wire to this ground rod.
|Size of neutral wire is same as that of the hot wire as they both carry the same current.
|Size of ground wire in individual branch circuits is dependent on the capacity of circuit breakers. In case of grounding wire at the main circuit breaker panel, its size is dependent on the incoming service wires.
|If wired properly, we can use neutral as ground wire.
|We cannot use ground as neutral as it doesn’t provide the normal return path for the current.
Ground and Neutral are two important conductors apart from the hot (or phase or live) wire in a typical mains AC Supply. Neutral wire acts as a return path for the main AC while Ground acts as a low impedance path to “ground” fault current. Neutral is normally a current carrying conductor whereas Ground is normally not a current carrying conductor. We learned the differences between Ground vs Neutral and understood the importance of both these conductors in our electrical system.