we know,there is parallel connection in power supply.but sometimes we find low voltage in some insruments at home.why

oltage drops are temporary and usually only last for a few seconds. Often this is a consequence of an older home with bad wiring, the transformer being too far away from the home, bad connections in junction boxes. This also happens in homes where there are large appliances. A large appliance makes a large draw on electricity. In electrical terms the higher the resistance the higher the voltage drop.