# Why is earth pin longer than other two in a plug top?

• Abhishakes
In summary: Normal plugs have two pins: the Earth pin and the live pin. The live pin is the one with the metal part that goes into the wall and the Earth pin is the one with the plastic part. The two pins are different lengths because the live pin is shorter so it can go into the wall first.
Abhishakes
Why is Earth pin longer than other two in a plug top?

By "plug top" do you mean a regular electrical plug, like this:
http://www.worldofstock.com/slides/BEN2097.jpg
If so then the reason the ground (or earth) prong is longer is simply so that it is connected before the live prongs. That way if there is a short you know you are grounded before there is a circuit.

Sorry if I misunderstood and you meant something more complex.

Last edited by a moderator:
A byproduct of this is the use of shuttered sockets. Here in the UK (presumably in other countries too) many wall sockets have shutters on the live and neutral connectors to prevent children (well, electricians too!) from sticking various objects into the socket and shocking themselves. By taking advantage of the longer pin and using it to open the shutters, you ensure that the live and neutral ports are only open just before the relevant pins are inserted.

Of course there's still a flaw with this. Electricians amonst others are prone to holding open the shutters through the ground port with a screwdriver; if they can do it so surely can children! Plus as the shutters open before the pins are fully engaged, you can fit small objects such as paper clips into them.

Both of the above

I think the three pin shuttered design is remarkably good for it's simplicity.

Ok, I think you know little Electrical stuff. In Electrical, current always flow through the easiest path that is lesser resistance. if you study about resistivity you can understand that resistivity is inversely proportional to the area (if area increases - resistivity will decrease). When you have short circuit the resistivity of the Earth pin is lesser (area is more) so the current will flow through this pin and will reach the ground. you can avoid shock.

To an extent, the Earth pin is only slightly longer.

## 1. Why is the earth pin longer than the other two pins in a plug top?

The earth pin is longer to ensure that it makes contact with the earth socket first when the plug is inserted into an outlet. This is a safety measure to prevent the live and neutral pins from making contact before the earth pin, which could potentially cause a dangerous electric shock.

## 2. Is the length of the earth pin standardized in all countries?

No, the length of the earth pin may vary slightly between different countries. However, the general principle of having the earth pin longer than the other two pins remains the same for safety reasons.

## 3. Can the length of the earth pin affect the performance of an electrical appliance?

No, the length of the earth pin does not affect the performance of an electrical appliance. Its primary purpose is for safety and to prevent electric shocks.

## 4. Are there any other safety features of the earth pin?

Yes, the earth pin is also thicker and has a larger diameter compared to the live and neutral pins. This allows it to carry more current and provide a low resistance path for any potential electrical faults, further reducing the risk of electric shock.

## 5. What should I do if the earth pin is missing or broken?

If the earth pin is missing or broken, do not use the plug and have it replaced by a qualified electrician. Without the earth pin, the appliance may not be properly grounded and can pose a safety hazard.

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