A wiring diagram shows the detailed wiring and connections between components or items of equipment and in some cases the routing of these connections.
It also shows the approximate position of the components in the actual equipment.
It may be shown completely or simply represented by a block with the necessary terminals clearly marked.
Lines of different thicknesses can be used to differentiate between the power and control connections.
It might be of a fairly simple circuit but it is quite difficult to use it to work out the sequential operation of the circuit. It is mainly to guide the wireman how to construct and connect the equipment. It is of little use in trouble shooting apart from identifying the exact position of suspect components and terminals.
Every piece of equipment generally has a wiring diagram etched / printed on one of its covers (on the inside).
Locate fault using wiring diagram
To locate a fault using this it might save a great deal of time and trouble to convert the wiring diagram to a much simpler and more useful circuit diagram.
When converting a wiring diagram into a circuit diagram, certain basic rules and conventions should be followed:
Converting ships diagrams
1. Every sequence / stage should be drawn from left to right and from top to bottom (where possible).
2. All contacts and components, which are in series, should be drawn in a straight line with the component they control (where possible).
3. All contacts and components, which are in parallel, should be drawn side by side and at the same level to emphasise their parallel function.
4. All major components operating at bus bar voltage should be drawn at the same level (or aligned horizontally) to help identify the required components quickly.
5. All contacts should be shown ‘open’ or ‘closed’ as in their normal or de-energised condition (N/O contacts will be indicated as ‘open’ while N/C contacts will remain ‘closed’).