Electronics Schematics: Crossing Your Wires

The lines in all but the simplest of electronics schematic diagrams will at some places need to cross over each other. When they do, it's vital that you can tell whether the lines that cross represent actual connections (also called junctions) between the conductors or the lines cross over each other but don't actually connect.

Unfortunately, there isn't one clear and universally used standard that dictates how to indicate whether crossed lines represent a junction. Instead, there are a number ways for showing crossed wires with or without junctions.

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The most common way to indicate a junction is by placing a conspicuous dot at the point where the wires cross. Any time you see a dot where two lines intersect, you know that the two lines form a junction. The vertical lines can also be angled to avoid coming together at the same spot on the horizontal line. With or without the dot, junctions are clearly indicated.

Lines that cross but don't connect to form junctions are most commonly shown as one line “hopping” over the other or as one of the lines broken at the spot where it crosses the other.

On occasion, you will see the lines cross each other. There's no hop or break to indicate that no junction is present, nor is there a dot to indicate that a junction should be present. So is there a junction here or not? The answer is, in most cases, no.

You can usually assume that a junction is not present when lines cross but there's no dot. However, you should examine the rest of the diagram to make sure. If you find other places in the diagram where nonjunctions are indicated by a hop or a break, the crossed lines without the hop or break may indeed indicate a junction.

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