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When using manual wire-numbering, it is important that you do this in a correct manner. If the wire-numbering contains errors, those must be corrected before you can produce any meaningful wire-lists. Otherwise, you will inevitably end up in a situation with serious errors in the wire-list, for obvious reasons.

 

There are several requirements, basic rules, which must be obeyed for the wire-numbering to be correct. These are described in the following.

 

In connection with wire-numbering, the terms “node”, and especially the variation “sub-node”, are used frequently. These terms are used in a way that is somewhat different in cadett ELSA from what might be common elsewhere.

 

In principle, a node is several connections (wires or cable cores) that are directly connected with each other so that they belong to the same electrical potential. A sub-node is almost the same thing. The main difference is how terminals and connectors are treated.

 

•On the other side of a terminal, you are still in the same node, but in a different sub-node.

 

•Terminals and connectors are treated as breaks for sub-nodes, but as connections for nodes.

 

Within a sub-node, all involved connection points are connected in a chain, a so-called "wire-chain". They are so to say “sewn” together, one after the other. First, the chain begins with an outgoing wire from the first connection point. This wire ends in connection point number 2 in the chain, where it therefore constitutes the ingoing wire. From there, the wire-chain continues with a new wire to connection point number 3, and so forth until all the connection points in the sub-node have been connected.

 

A consequence of what is said above, is that "sub-node" and "wire-chain" in principle are two words for the same thing.

 

Within a sub-node, there are never more than two wires connected to each connection point, one ingoing and one outgoing.

 

To symbols for conventional devices, you typically draw one line to each connection point in a circuit diagram. Normally, this means that you will have a maximum of two physical wires connected to each connection point. In most cases, this corresponds well with practical limitations.

 

For terminals, the situation is however quite different. To a terminal symbol, you can draw lines in multiple directions at once, and each line may represent up to two physical wires. The theoretical limit is therefore 8 wires to one single terminal, if you draw four orthogonal lines to it. By introducing lines in a 45 degree angle, its is even possible to extend this to 16 wires, but that would be a violation of both the IEC standard, and of good practice. It would also be associated with many other disadvantages and is therefore not recommended.

 

Besides from all that, terminals are also divided in an internal and an external side. That is, however, a chapter of its own.

 

Please note that what is said above still primarily refers to the physical reality, not to the circuit diagram. Two physical wires do not need to be drawn as two lines. A single line in a circuit diagram may very well represent two physical wires in reality.

 

Each wire (electrical connection, conductor) has a unique wire-number.

 

This means that a connection point of a symbol, can have no wires connected, one wire connected, or two wires connected. In a circuit diagram this is always drawn as one single line, but that line can represent up to two wires.

 

Below, the simple basic rules which define a correctly wire-numbered sub-node are stated:

 

1.Connection points which are not connected to anything, should not have any wire-number symbols.

 

2.In the beginning of a wire-chain, there must be a connection point with one outgoing wire-number only.

 

3.In the end of a wire-chain, there must be a connection point with one ingoing wire-number only.

 

4.In all other connection points of a wire-chain, there must be both an ingoing and an outgoing wire-number, where the ingoing and outgoing wire-numbers must differ.

 

5.Each outgoing wire-number must have a corresponding ingoing wire-number in the same wire-chain.

 

6.There must never be two or more identical ingoing wire-numbers or two or more identical outgoing wire-numbers in the same wire-chain. Expressed differently, it is forbidden to have several wires with the same wire-number in the same wire-chain.

 

The lines that you draw in the circuit diagram to define which symbols are connected to each other are only there to define the electrical connection. They have nothing to do with the wiring sequence. They should not have that either, since a circuit diagram primarily defines the function of a design, not the physical realisation of it. The wiring sequence is completely controlled by wire-numbers.

 

It can however be noted here, that other document types can exist, such as connection diagrams, where the connection sequence is shown graphically. Such a document can be seen as a graphical wire-list and should not be confused with a circuit diagram, which is a function describing document.