Answer to Question #291083 in C++ for jay

Question

A. With the use of a suitable diagram explain how a person can get an electrical shock from touching an unearthed isolator. State ONE (1) precaution that can be taken to prevent a reoccurrence

Answer 1

The case goes live when a fault develops in an un-earthed metal cased gadget. When you touch it, a circuit is formed. You'd assume current couldn't flow through solid wood or something like that. That would be true in the case of DC, but not in the case of AC. You see, you're a capacitor component. You're essentially one of two capacitor plates, with the ground being the other. The dielectric insulator between the two is formed by the floor, your boots, and other items. The capacitor would block any DC current, but it allows the AC to flow quite happily. The resistance of your body, and the resistance of the ground both limit the amount of current, but it only takes a tiny amount to kill you.

When a problem occurs with the case grounded, which usually entails a wire connecting the ground direct back to the ground point, which is also linked to neutral, the electricity will travel straight down the earth wire back to the neutral. Because this is a much lower resistance connection than any human could make, a lot more electricity can pass. The circuit is isolated as a result of the fuse blowing.

Furthermore, if the fuse fails to blow for whatever reason (too high a rating? ), the low resistance path effectively shorts out the person, decreasing the current available to shock you to a negligible amount. The equivalent circuit would be the on shown above