Computers, printers, fax machines, stereos, calculators, copying machines, you name it - if it has an electric cord it very likely has one or more computer chips that control some function. Chips are everywhere and they are multiplying like rabbits. They make our lives less complicated but when a chip burns up because of a voltage surge, our lives can become miserable about as fast as the surge roared down the power line.
One reason electric surges are becoming more of a problem is because computer chips are becoming more efficient. In other words, the distance between the electrical pathways on the chips is shrinking. This means that it takes less electricity to arc across the borders between the pathways.
Surges are also becoming a problem because of the deregulation of the electric industry. Electric utility companies are now having to deal with electric coming from many different sources. This wasn't such a problem years ago when just your electric company generated power. If they needed more juice they would simply make the buy and prepare for the delivery. I believe it is much more complicated today with the net result being an increased possibility of electrical surges sneaking into your local electric distribution network.
Lightning and Ground Wires
Lightning strikes near your house or in your neighborhood can cause all sorts of problems. The huge voltage surge can travel down electric lines, telephone and cable TV lines. This rush of current is hunting for a place to go. It wants to go to the ground, but if it can't get there quickly enough, it will search out and destroy things in its path until it does find adequate pathways to the ground.
You can stop much of this damaging current with protection at your electric panel. This protection may include a surge protector, sacrificial lightning arrestors, oversized grounding wires and ground rods to dissipate the massive quantities of electricity. Think about it - imagine trying to drain a swimming pool through a drinking straw. That is not a good fit. Standard sized ground wires work fine for regular dead fault short circuits. They are no match for the massive amounts of amperage / voltage contained in a lightning strike. Never, ever underestimate the power of Mother Nature.
Plenty of Protection
If you want solid protection for your household electronic equipment, I feel you need to install two levels of protection. A whole house surge suppressor will absorb many - if not all - surges that originate outside your home. The point-of-use surge protectors that connect behind your computer and stereo will do that as well. They will also capture larger surges the might originate inside your home.
The surge suppressors you buy must have the highest joule rating possible. These ratings represent how many metal oxide varistors (MOVs) are inside the suppressor. The MOVs are sacrificial. Each surge no matter how large or small eats away at the MOVs. Eventually, the MOVs inside the suppressor will be destroyed. You want as much protection for as long a period as possible.
I have always been a Doubting Thomas. I have used surge protection equipment for years, but in the event of electrical storms, I always unplug my protector from the wall outlets. This automatically isolates all of my computer equipment from any possibility of damage.
I suggest you think about doing this as well, especially if you plan on leaving your house for vacation or some other reason. It seems to me that this plan offers the highest level of protection. I know what lightning can do as my house suffered a strike or near strike 10 years ago. We came home and all of the smoke detectors were blaring, the garage door openers were fried, the VCR was toasted, 5 circuit breakers were ruined, and all of the GFCI outlets were burned up as well.
Virtually every surge suppressor sold today comes with a connected equipment warranty. This is good coverage, but be sure you know what is covered and how you can make a valid claim. I urge you to create a file folder that you keep all product packaging, receipts, instructions, etc. You may need these things to make a claim.
Also keep in mind what the warranties don't cover. Think how many hours you might have invested in electronic files on your computer. You need backup data storage for this, not a warranty! Don't forget, tapes in computer tape backup drives can be fried if they are left inside your computer!