ammeter

[Stuart Giles]

If you have a Lucas SM5 switchpanel, reversing the ammeter connections "B" and "A" will not result in correcting the ammeter reading -the reading being the wrong way round on a positive earth car. If you look at this diagram of the SM5 switch panel you can see why. The "A" side has hard wired connections with the brass trace to the two switches and so, the entire vehicle electrical load -lights, ignition etc. By connecting the "B" wire to this "A" terminal you would ensure that the ammeter will not respond to any item switched by the panel, because it now has a direct battery feed. Conversely, connecting the "A" wire to the "B" terminal will mean that the ammeter will show the Dynamo's charge; but not the nett charge after loads like the ignition etc.