Circuit Breakers and Circuit Overload

Circuit Overloads are a common fault on most appliances. The cause of this is excessive current being drawn from the appliance and applied to surplus wires. Circuit breakers are designed to manage this situation and cut the power to the breaker. However sometimes this is not enough and a trip or overload occurs which will result in damage to the appliance and possibly shorting of the circuit.

There are three main types of circuit overloads. The first is conducted load, this is usually caused by tripping of a component which in turn will draw amperage. The second is thermal overload which occurs when thermal insulation melts and draws amperage, this is normally caused by a short-circuiting process within a fuse. Finally there is an overload caused by direct current (DC) that is trying to do work but gets stuck.


You can prevent these potential circuit breakers from happening with some simple precautions. If you have an appliance that requires many power points, one option is to use surge protectors and fuses which can be bought from any good electrical retailer. Make sure that all the wiring in your home is properly insulated as there is no point in plugging multiple appliances into one circuit only to find that it shorts out the breaker.


Circuit breakers will generally be rated based on maximum load (or amperage). This means that the higher the rating the more power supplied to the circuit. It is important to ensure that the correct maximum load rating is entered into your circuit design. In practice this will usually be around double the measured maximum wattage of the appliance.


Circuit loads will vary greatly depending on the appliance and its typical use. For example a hair dryer, which uses a 1,200 wattage bulb will generate three amps of electricity. Assuming the circuit is designed to handle this load, then one potential problem would be overload. The rule-of-thumb for calculating a potential overload is: The current required to run one amp of load multiplied by the maximum allowable load on the breaker’s opening. Unfortunately a lot of people make this mistake, which leads to a lot of failed appliances and costly accidents.


One of the best protections available for circuit breakers is a combination of fuses and circuit breakers. Fuses can often be placed on the outside of the circuit breakers where they cannot be reached by small hands. Fuses can also be placed inside the circuit breakers but be careful as power boards containing these often suffer damage when touching other fuses and fuse holders.


To detect an overload you should pull a voltage from your wall outlet and measure the measured current against the maximum safe current (or amperage). If the current is too high, it could indicate a trip to a breaker or fuse that has either tripped or blown out. Common reasons for an overload are insufficient amperage or poor wiring. Sometimes appliances can overheat, which can lead to burnt fuses or breakers.


It is important to understand the relationship between amperage and load rating when evaluating circuit breakers and fuses. The amperage is expressed in amperes or amps and a load rating expresses the maximum achievable voltage that the circuit can safely handle. To calculate a load rating, divide the amperes by the total voltage the circuit can safely handle. The rating is usually written on the circuit in reference to amperage. For instance, a five ampere circuit can handle one hundred thousand amperes and a five-watt circuit can handle two hundred thousand amperes. These figures can only be used for approximate calculations.


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