Electrical safety for both people and property is an significant consideration is using electricity. For instance, in household circuits, as more and more appliances are turned on, more and more current flows and the wires get hotter and hotter. At what time too much current flows, the fuse gets so hot that it melts and acts as an open switch. The damaged fuse stops any current from flowing until the fuse is replaced.

A circuit breaker has the equivalent function as a fuse. When the current gets too high, the circuit breaker triggers a switch to open, halting any kind of current from flowing. When the trouble is repaired, the circuit breaker can be pushed in to close the switch, and current can again flow in the circuit.

Switches, fuses, and circuit breakers are always placed in the hot or high-voltage side of the line so that when they are opened, current flow is disconnected. However, fuses and circuit breakers may not always give safety from electrical shock. A hot wire inside an appliance or power tool may break loose and come in touch with a housing or casing, putting it at a high voltage. The fuse does not blow if there is not a large current flow, suchlike when being shorted to ground (zero potential).

You have presumably noticed that some plugs have one blade larger then the other and will only fit into a wall outlet in one way. Polarized plugs are an older type of safety mark. Being polarized or directional, one side of the plug is all the time connected to the ground side of the line. The casing of an appliance can be connected to ground by this means, with a like effect as the three-wire system. However, a dedicated grounding wire is better, because the polarized system depends on different components of the circuit being wired or connected properly.

An electrical shock can be very dangerous, and touching exposed electric wires should constantly be avoided. Numerous people are killed every year though electric shocks. The danger is proportional to the measure of electric current that goes through the body. Ohm's law as described below gives the amount of current going through the body.

Where = resistance of the body.

A current of 0.001 A (amp) can be felt as a shock, and a current as low as 0.05 A can be fatal. A current of 0.1 A is almost always fatal.

The amount of current, as indicated, is very dependent on the body's resistance. The body's resistance varies considerably, mostly due to the dryness of the skin. Because our bodies are generally water, the skin resistance makes up most of the body's resistance.

A dry skin will have a resistance as high as 500,000 , and the current from 110-V (volt) source will be 0.00022 A. The hazard occurs when the skin is moist or wet. Then the resistance of the body can do as low as 100 , and the current will rise to 1.1 A. Injuries and death from shocks generally occur when the skin is wet. Therefore, appliances such as radio should not be operated near a bathtub. Should a plugged-in radio happen to fall into a bathtub, then the whole tub, as well as the person in it may be plugged in to 110 V.

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