Grounding Wire?

Question

I assume the wiring in Britain is similar to the United States that in simple house circuits, a hot, a neutral and a ground wire exists in modern wiring. That is, for a regular wall outlet.

The believe the ground is there to provide the least amount of resistance and hopefully, in the event of a short, the electricity will travel through it and not you.

The gournd and neutral wire are two different wires but go to the same bar. Why? I'm sure there must be a reason, otherwise, a same neutral wire could be cross-wired into a three-prong outlet to to supply the neutral and ground at that level rather than all the way back to the bus bar. There's obiously a reason to do it with three wires.

Answer 1

In the UK, the neutral (blue/black) is NOT connected to or regarded as part of the earthing system. That is down to the yellow-green striped/green wire ! ! !

Answer 2

The best way is to have the ground other than the neutral. The ground is connected to the body of the applience for safety purpose. So that due to some fault, if the hot wire inside the applience touch the body, even then the person should not experience lethal level of electric shock. The earth point does not carry any current normally.

However, the neutral point does carry the current and so, at the applience end, the neutral point has some voltage more than the ground potential. If the ground point is connected to the neutral, then it is likely that the person using applience may feel shock when the short circuit / overloading is elsewhere.

As a practice, the neuatral and ground are connected, but at far end, like sub station or distribution transformer end to avoid problem as mentioned above.

Answer 3

it is similar but not identical. we call the "Hot" the "Live" and the "Ground" the "Earth" but as you have realised the neutral is connected differently.

the ground is connected to be of a route for the current to take during a short circuit (thus preventing the user from being the path of the current).

depending on the type of installation the ground and neutral may be combined or seperate upon incoming to the distribution board, this varies depending on the supply system for each building (but mostly areas will all be wired the same way).
sometimes supplementary earthing measures are required and the building owner has to provide a earth rod (which gets buried deep into the ground).
The reason for keeping the earth seperate from the neutral is to allow operation of RCD's and to prevent backfeeding if the neutral becomes disconnected at the distribution board.

Answer 4

With many installations now incorporating an RCD it is important to keep neutral and earth wires separate as the RCD compares the current of the live and neutral circuits and trips if there is a difference. If some or all of the current was diverted to earth through the earth wire the RCD would keep tripping. However you are right that at some point in the supply the earth and neutral are connected, this guarantees that the neutral is always at zero potential, it is not meant as a current carrying connection.

Answer 5

You never want to cross wire the ground and neutral wires. The both go to the same bar at the meter. This bar also goes to the ground-rod or water pipe and puts the ground wire at zero volts.

The reason you don't want to cross these wires is the ground wire is for safety, the neutral wire carries current. Outlets are wired poiny to point. There could be several other outlets between you and the meter. If the ground wire is carring current thwre is IR losses in that wire, That makes the ground wire at some voltage above zero volts. This can cause shock or death!

Answer 6

You are right the neutral does end up in the earth to provide a return to the power station and make the circuit. The earth does the same but it is a safety device so gets to earth the quickest way possible while passing through the minimum of joints and other fittings. A lot of modern equipment is double insulated so does not require a earth wire and you only get the two connections

Answer 7

in canada & america the national electrical code ruled that the supply side of main disconnect, the neutral and system ground wire shall be connected to the main water pipe. the reason is for safety, to limit the voltage to ground to below 150 volts. only that point is connected to ground, the rest of neutral is floating to avoid current circulation.