Basics of electrical power
Electric power is the product of two quantities: current and voltage. These two quantities can vary with respect to time (AC power) or can be kept at constant levels (DC power).
Most refrigerators, air conditioners, pumps and industrial machinery use AC power whereas most computers and digital equipment use DC power (the digital devices you plug into the mains typically have an internal or external power adapter to convert from AC to DC power). AC power has the advantage of being easy to transform between voltages and is able to be generated and utilised by brushless machinery. DC power remains the only practical choice in digital systems and can be more economical to transmit over long distances at very high voltages (see HVDC).1415
The ability to easily transform the voltage of AC power is important for two reasons: Firstly, power can be transmitted over long distances with less loss at higher voltages. So in power systems where generation is distant from the load, it is desirable to step-up (increase) the voltage of power at the generation point and then step-down (decrease) the voltage near the load. Secondly, it is often more economical to install turbines that produce higher voltages than would be used by most appliances, so the ability to easily transform voltages means this mismatch between voltages can be easily managed.14
Solid state devices, which are products of the semiconductor revolution, make it possible to transform DC power to different voltages, build brushless DC machines and convert between AC and DC power. Nevertheless devices utilising solid state technology are often more expensive than their traditional counterparts, so AC power remains in widespread use.
Work on the home electricity
Although many people isolated attempts to control the domestic installations, usually professional help is highly desirable especially in more complex cases. As far as changing a light bulb or perform other similar tasks require more visits electrician so much already in the case of laying wires or installation of distribution are more complicated. Isolated executed electrical installations can make later, at the stage of operational problems arise, for example, through the inclusion of too many devices to the power supply circuit may occur. So let's take care of it, to the more complex work carried out specialist, because working with electricity can be dangerous for inexperienced employee.
Most electrical services during the construction of the house
When it comes to houses, many electrical work is needed at the stage of construction. At the appropriate time work is carried out in respect of manual excavation in which the wires are subsequently stacked. Then, when the walls have been rebuilt there is a need to distribute the system throughout the house. He then are assembled separately, and all kinds of electrical outlets, of which the inhabitants of the house will later use. Of course, they are responsible for bringing the electrical system to the possibility of exploitation. Often electricians are also involved in installing electrical systems, such as intercom systems, which are quite useful, especially when dealing with a compact architecture.