Electrical wiring according to places such as skyscrapers, towers and other power wiring is currently in the wall, which is hard to verify if any point there is no electrical power.
From observing electrical wiring according to the building is embedded in the wall cabinet and then present a sky electricity monitor AC (AC) By using the Light emitting diode and LED bulbs are known as sound in General, which can be useful in checking the wires according to the different buildings that can't be taken out, such as checking if the power cord was broken in, they will be able to check easily and does not compromise user tools.
The experiment found that a check AC power can check the actual power by checking if there is electricity, there will be loud, but if you don't have the power, there will be no sound.