"Short circuit"

[Barry Wolk]

As a newbie here I've been reading a number of posts here that use the term "short circuit". It is most often misused as a short circuit is a direct connection between the power source and a ground that causes a wire to burn or a fuse to blow.

There are a number of reasons for blown fuses and a short circuit is only one of them. One is the direct connection to ground and the other is consumption of electricity beyond the capacity of the filament in the fuse.

If some device isn't getting current it could be due to an "open circuit" like a blown fuse or a loose connection. In the case of the horn the horn button is an intentional "open circuit" that gets completed to ground when the button contact closes.

Many electrical automotive problems come from loose ground connections. This will cause intermittent operation and can result in fires as loose connections create resistance and resistance causes heat. It's very important that the ground strap from the engine to the body has a good metal to metal connection as it is the return path for the power to return to the battery.

Many other problems come from substituting battery cables that were designed for 12-volt cars. Those cables can only carry half the current of a cable designed for 6-volts and will heat-up substantially during heavy current draw. That heat actually makes the problem worse.

I am an electrician by trade and love problem solving on old cars. Let me know if I can help. And, thanks for the warm welcome here.