The ease and convenience of having appliances and other electronic devices is a hallmark of the modern home. For the most part these are now becoming intelligent devices which are able to learn from constantly interacting with humans. Most modern devices have high durability that exceeds the warranty by a wide margin. This is not to say that they do not break; instead, what happens is that they are designed to be more resilient and capable of taking punishment.

For instance, a lot of appliances which use an electric motor have built-in controls to make sure that they operate within expectations and a wide range of operating environments. These appliances can be used continuously for longer periods of time, without any danger of overheating. As long as they are working within allowable operating environments, no problem should arise.

What has changed a lot is that these same appliances no longer use internal fuses. They now use what is called a miniature circuit breaker. Simply put, it works like a circuit breaker, but miniaturised to handle the stresses and smaller voltage requirements of an appliance. You might not notice what it looks like, except for the switch which is used to reset the device.

A built-in miniature circuit breaker (also called an MCB) works like a trip wire in case of voltage overload. When there is a big power surge, a large amount of electricity passes through the wires and can destroy running electrical devices. Usually, this is caught by the home’s circuit breakers. Sometimes, however, the circuit breakers or fuses don’t trip fast enough and the electrical surge goes through the plugged-in appliances. They have their own circuit breakers that get triggered by the heat generated by the surge. The switch opens, and the extra power does not reach the sensitive parts of the appliance.

The MCB is a small piece of equipment, which is used to protect electrical devices. The regular homeowner does not need to concern himself about it. The only thing he has to know is to push the reset button when an appliance dies, and to start diagnostics from there.

In case your appliance does not have an MCB, there is a danger that the electrical surge will pass through the appliances components. These are not capable of handling electrical surges, and can burn out due to the energy which passes through. When this happens, the appliance will not turn on properly. It is practically dead and will typically require fixing by qualified technicians or repair personnel.

Electrical surges are not really very common. Most of these are arrested by the home’s circuit breakers. One source of electrical surge is when you have a 110 volt AC device plugged into a 220 volt outlet. The home’s circuit breakers will not be able to help in preventing any damage. Another instance is when lightning strikes. By design, a house is well capable of channeling the static electricity to the ground. However, in some cases, the power surge may enter the electrical system and go through the appliances. Some might survive, while a minority will not. In most cases, the appliances can survive a lightning strike on homes. It is for the minority of cases which the MCB was designed for.