Positive earth, 6 volt batteries, funny colored wires? What the heck is it with Lucas wiring?These are the most common questions we get about the wiring on vintage Brit bikes. From all the jokes about Joe Lucas a.k.a. “The Prince of Darkness” Brit bike wiring has gotten a lot of fun poked at it and an overall bad rap.
Let’s start with the “Positive Earth” debacle or debate. Although the negative charged electrons move through the wire toward the positive (+) terminal of the source of electricity, the current is indicated as going from positive to negative. This is an unfortunate and confusing convention.
Ben Franklin originally named charges positive (+) and negative (−) when he was studying static electricity. Later, when scientists were experimenting with electric currents, they said that electricity travels from (+) to (−), and that became the convention.
This was before electrons were discovered. In reality, the negative charged electrons move toward the positive, which is the opposite direction that people show current moving. It is confusing, but once a convention is made, it is difficult to correct it.
What does this mean to a vintage Brit bike? Well, the frame becomes the cathode in the circuit, the cathodic reaction is then directed at the frame rather than the components within the circuit, i.e. the sacrificial element.