brownout, which accounts for most power problems. Anything higher than 132V is called a spike. It might seem like your electricity is reliable, but chances are that your home endures many short brownouts and spikes every day.
Your computer should never be plugged directly into the wall socket. At minimum, it should be plugged into a surge protector, not just a power strip, regrettably they look the same. Power strips are basically just a series of electrical sockets combined that enable you to plug in multiple devices, they do not offer any protection. Get a surge protector with at lease 1500 joules protection.
Every computer component, including the printer, external drives, hubs and cable modem, should be plugged into a surge protector. Don’t plug the PC into an outlet that’s on the same electrical circuit as high demand equipment such as an air conditioner or refrigerator. The sudden power draw that occurs when the appliance turns on can cause small brownouts for other gadgets on that circuit (e.g. your main home PC).
If you are home during an electrical storm, the best way to protect your equipment against sudden damage is to unplug your computer from the electrical outlet. It's always better to be safe than sorry.