Answer:
1) Electrical surges
It can be occurred due to poor wiring in the house or lightning strikes or faulty appliances or damaged power lines. Surges are common and last for a microsecond but if you experience frequent surges lead to equipment damage that degrade life expectancy particularly.
Check the device that connects to the home grid or the wiring and try disconnecting the poor quality powerboards or devices from the outlet. If the surges don’t occur again, your problem is solved. If it is not, you must call an electrician.
2) Overloading
Sometimes your light fixture has a bulb or other fitting with high watts than the designed fixture. This is a code violation and the risk level is quite high. The high heat from the bulb can melt the socket and insulation present in wires of the fixture. This results in sparks from one wire to another and causes electrical fires. Even after the bulb is removed, the socket and wires will still be under damage.
It is always better to fit a bulb or any other fittings by staying within the wattage. If the fixtures are not marked with wattage, it is advisable to use a 60-watt bulb or even smaller ones.
3) Power sags and dips
Sags are dips usually occur when the power grip is faulty and electrical appliances are connected to it. It also occurs when the grid is made of low-quality materials. When this is the case, it draws more power when switched on.