The statements posted by the gentleman from New Zealand, are a good example for my questioning some of the terms, we in the US, use in referring to various electrical systems. My limited education in the various countries, I have worked, and examining their technology approach, has revealed a sharp contrast in definition. Countries using the system described as a (MEN) multi earthed neutral system, include all conductors that are electrically connected. Our terms of neutral, grounding electrode conductor, bonding, and equipment ground conductor, imply that each is a different system. Their purpose may be for different reasons, but they are one system, and considered a direct connected circuit conductor, in most countries, except here in the US, as defined in the NEC when addressing separately derived systems. The definition of the term neutral is that it a component of the MEN system, intended to carry load and fault current. Ground electrode conductor is a component of the MEN system, intended for carrying parallel fault current, and transient surge current. Equipment ground conductor is a component of the MEN system, intended to carry fault current. I have no problem with these definitions. Remember Europe had transmission, distribution, and secondary voltage transformers before the US. This MEN concept was established, as the safety grounding system. We use this concept in our utility application as a MGN system. I have never seen reference to MGN in the NEC code book.
We in the US, usually end up with the same system as the MEN concept. My problem is in the educational and learning process the system conductors are referred to as individual systems, and not as components of only one system. Defining as one system, individual definitions of each component is not necessary, only its function needs to be known. The identification of its function is done by color marking. I view a multi grounded neutral system as a single circuit network, it includes all neutrals, ground electrode, bond and equipment ground conductors. At least one conductor, of this system, will connect at every electrical device in a facility. The points of connection, ampacity, and identification, is dependant on its function. This is the European approach, which I can understand easier than our multiple definitions, exceptions, references, exclusions, and fine print notes explaining grounding and bonding.
#76844 - 03/25/0108:03 PMRe: International Technology
i am not saying our system is any better than anyone elses. We have a POM that works with us ocassionally he has said and i remember from living in London there system is somewhat different than ours, they ring main there sockets also they are indiviually fused behind the socket faceplate, voltage,HZ the same but its not called a MEN system i will ask him to explain again.
#76845 - 03/25/0108:15 PMRe: International Technology
Appy: I did not take your responses to imply a better system. It is the same system as used in the US. The point I was trying to make, is that the different terms we use, create confusion, and misunderstanding of the purpose, of a grounding system. We have different terminology by "stump jumpers" and "narrowbacks" in the electrical trade, here in the US.
#76846 - 03/25/0109:16 PMRe: International Technology
""stump jumpers""narrowbacks" Are these different types of trades people in the US. it must make it very difficult to understand what people are talking about when visiting or working interstate, I must admit i had trouble understanding people when i had to deal with a supplier from Salinas CA and they had no idea what i was talking about. Maybe a nationwide book of terms instead of codes would be advantageous
#76847 - 03/25/0109:33 PMRe: International Technology
This is how i understand it A fused feed out that rings the entire installation with all the socket outlets connected to it that comes back to the same fuse. "A Ring"... i suppose they save on cabling and easy to fault find etc. supposedly We do our street lighting the same way incase one end gets whacked by a misdirected car the other side will carry on working but you gotta be careful when isolating to work on them!!!
[This message has been edited by old Appy (edited 03-25-2001).]
#76849 - 03/25/0110:23 PMRe: International Technology