Why is Earth Pin Thicker and Longer in a 3-Pin Plug?
We know that electricity is our best friend as well as the worst enemy because if you give it a chance to kill you, remember, it will never disappoint you. Now you know that it’s all about safety and protection.
We also know that all the electrical appliances with metal bodies should be properly earthed and grounded. The reason behind this logic is that in any case, the Live (Line) wire touches the appliance metallic body, or in case of short or leakage current inside the appliance, and someone touch the metallic body of the machine, current will flow through the human body to the earth i.e. electric shock.
This is why proper earthing (grounding) is necessary to protect you and the person who touch the metallic body of the machine don’t get electrocuted.
In a 3-pin plug ( as shown in the above fig)
- The Green & Yellow Wire is Earth (IEC & NEC)
- Brown is Live / Line (Black in US)
- Blue is Neutral (White in US)
Now to the points, why the earth pin is bigger and thicker?
Why is it Longer?
The earth pin should be the first to connect and the last to disconnect with electric supply. This is why earth pin is longer than the live and neutral pin on 3-pin plugins. Below are the the reason to do so,
- When we insert a 3-pin plugin into a 3-pin socket, the earth pin is the first to make a contact with the socket as compared to the Live and Neutral Pins.
- The earth pin is the last to disconnect from the socket when removing the plug from the socket. i.e. Line and Neutral disconnect first and then the earth pin.
This way, earthing is well maintained during the operation for proper safety and protection. Now we know this is why the earth pin is longer as compared to Line and Neutral Pin on a three pin plug.
Why is it Thicker?
First reason, to prevent the wrong way to operate a 3-pin plug and connected electrical machine for the safety purpose. In other words, 3-Pin plug wont be connect to the socket upside down as the earth pin is thicker, so it won’t adjust and fit in another slot made for Neutral or Live Pin in the socket.
In short, The earth pin is bigger and it can not be inserted in the live or neutral slot of the socket even by mistake.
Second reason for thicker pin is that the law of resistance.
R = ρ (L/a) … [ Law’s of Resistance)
Where:
- R = Resistance
- ρ = Resistivity
- L = Length of the Conductor
- a = Area of the conductor
It clearly shows that the resistance is inversely proportional to the area of the conductor. i.e. thicker of the conductor, lesser is the resistance. In this case, when a wet body (Keep in mind that wet body has very low resistance) touches the metallic body of the machine where leakage current exist. Current will flow through it as it find easiest way (having very low resistance) to complete the path. So there is still a chance of electric shock in the above mentioned case.
Third reason, modern 3 pin wall sockets have safety shutter (as shown in below fig) on the Line and Neural lines to prevent someone (especially children) to insert conducting materials in it which cause electric shock. In this case, the longer earth pin help to open the shutters for Line and Neutral pins i.e. without longer earth pin, The shutters for Line and Neutral remains closed for better safety.
Now we know another reason, that’s why the Earth Pin on a 3-pin plug is bigger than the Neutral and Live pins.
FAQ
Why the earth pin is thicker and longer in three pin plug?
Note: Whenever such types of questions appear then first know about the three pin plugs, about the pins and their names. Then as mentioned in the solution, the earth pin is made longer and thicker to ensure our safety if any fault occurs. This increases the efficiency
Why does a 3pin socket have diameter and length more for an earthing pin?
Its longer than the other two pins because when you insert the plug,the earth pin will first come in contact with the power supply before the other two(live and neutral) so that any unwanted charges which may be in the circuit will be removed(grounded) before the other two pins go inside the terminals
Why is the earth hole size biggest in plug points?
The diameter of the earth pin is larger so that it can carry major portion of current(causing shock ) as it’s going to be in contact of earthing wire. This is a important safety measure
Why does a three pin plug include an earth pin?
Without the earth wire, if a fault occurs and the live wire becomes loose, there is a danger that it will touch the case
What is earthing in 3-pin plug?
Third pin provides an earth connection. When we insert the plug in a socket, the earth pin is the first to come in contact as compared to the rest two. As earth is directly connected to the metallic body and then to the ground, it creates a safe a short route for the device in case of any short circuit
Why all three pins are splitted in a 3-pin plug?
Why are there cuts/splits on the tongs of a three pin plug? To make pins slightly flexible in thickness and allow to fit in socket properly n avoid and loose contact
Why is the earth pin bigger on a 15amp plug?
1 Answer. Generally the ground pin is a bit longer and can carry more current than the other pins because it’s more important in case of a failure of insulation in the device for the ground connection to remain connected long enough for the fuse or circuit breaker to open the circuit
Which plug has a bigger earth pin?
The 15 A outlet has a wider Earth pin than the 10 A outlet. The 20 A outlet has a wider Earth pin and wider Line and Neutral pins. The 25 A outlet has an inverted L-shaped Earth pin and wider Line and Neutral pins
Why do sockets have 2 earth terminals?
Often there are two earth terminals, but both are not needed they are just there for ease of wiring
Why is the earth pin longer in a 3 pin plug?
Earth pin is thicker so that it does not enter into the live or neutral sockets. It is made longer so that it gets connected to the earth terminal earlier than the live and neutral pins. This ensures the safety of the user
