To properly protect your sensitive electronic equipment you must construct a barrier around it much like you would put a fence around your home. Since you usually can't prevent the things like lightning that damage your home electronics, you must keep these conditions from getting to your important equipment. Every piece of electrical equipment in your home needs a barrier.
Just as it would be silly to dead bolt your front door, then leave the windows wide open, the same is true of your electrical equipment. Every avenue to the outside world must be protected - power, phone, cable, data and control lines must all be protected or your equipment will be vulnerable to damage.
Begin power protection at the main power entrance, the point where your power, cable and phone lines enter the house. By installing a high-energy surge protection device at this location, you can knock down the first wave of high voltage spikes entering your home.
Most contractors call these lightning arrestors. But, don't confuse these devices with a lightning rod. Lightning rods are installed to protect the house from physical damage in case of a direct hit. They won't protect electrical equipment inside the home. The lightning arrestor is a device that helps divert damaging surges away from your electrical system and out through your ground rod.
The cable TV line will probably enter your home near the main power entrance as well. It's best to have all of your utilities enter your home at one point because it allows you to tie all of their ground rods together to form a single grounding system. This is required by some codes but it's often overlooked by cable installers. Unless all of your equipment ties into a single ground, protection against surges won't be as effective.
Moving inside your home, the television, DVD, DVR, CD player and stereo system represent a considerable investment, and they can be easily damaged by spikes. Each should be plugged into a plug-in surge protector. Use a protector that has multiple outlets allowing one device to protect your entire entertainment center. If you have cable service, the lead into the house should be surge-protected as well.
Everything should be protected. If you protect your stereo but leave the CD player unprotected, the connection between the two devices provides a path for spikes. Some appliances containing electronic controls (i.e. microwave ovens) may also require surge protection. Make sure you use a surge protector designed for "heavy duty use". There are surge protectors designed especially for microwaves.
Telephones and answering machines are some of the most commonly damaged devices in the home. A plug-in surge suppressor should be used to protect the power and phone line inputs. A common mistake is protecting only the power line. This does not provide adequate protection. Using a device that contains both protection elements in a single package is best and ensures system compatibility. These devices will have inputs for the phone line and the electric plug. If either line goes directly to the equipment, the equipment is not completely protected.
To prevent the flashing "12:00" problem, look for clocks and DVD players with built-in battery back-up. Battery back-ups are not designed to keep the unit operating during a power outage, but it will preserve the memory and settings so they will still be there when the power comes back on.
*Source – US Energy Information Administration