[Amps] Electrical Distribution Methods

[peter chadwick]

>In nearly all countries, neutral is connected to the 
 ground wire, but WHERE and HOW it is connected varies widely from one 
 country to another. In North America,.neutral must be bonded to the 
 "green wire" (ground) where power enters a building, and again at the 
 secondary of any transformer.<

While in the UK, neutral is connected to earth at the transformer secondary and a number of points along its run. If the building is on a system known as Protective Multiple Earthing (PME - which for some of us causes as much trouble as PMS!) the neutral is bonded to all metalwork such as sinks, heating and water pipes, gas pipes etc. in the house and also to the earth pins of all the sockets. Then you are not allowed to have anything connected to an earth in the outside world  within 6 feet of any of the bonded metalwork in the house. The argument is that it gives a better earth for most people and allows the use of 'advanced technology'(i.e. cheaper!)LV distribution cables......

Fortunately, you can refuse to have PME and have a local earth, but it has to be less than 10 ohms. Not many people know that, even in the electricity suppliers. The whole thing can be a pain for amateurs.  

Note: phase to neutral volts = 220, phase to phase volts 381
      phase to neutral volts = 230, phase to phase volts 398
      phase to neutral volts = 240, phase to phase volts 415

73

Peter G3RZP