How to Choose Surge Protection for Your Home
You may not realize it, but your stereo system, home computer, television, VCR, microwave oven -- anything with internal electronic circuits -- is under attack every day. The attacks are silent, but destructive.
The culprit -- POWER SURGES. Power surges are extremely brief spikes in electrical power that burn up the electrical circuits inside appliances and electronics. For more detail about what power surges are and where they come from, read Facts about Power Surges.
Not only can power surges destroy appliances and electronics, they can ruin electrical outlets, light switches, light bulbs, air conditioner components, and garage door openers. How can you protect yourself?
Surge protection devices can prevent the damages from most power surges.
There are two types of residential surge protectors:
For the typical home, many experts recommend a minimum surge protection network consisting of:
For home office or special medical needs, additional and different protection from other types of electrical power interruptions may be appropriate as well.
There is no surge protection device or system that can protect against all power surges. A direct lightning strike to the house's electrical system may be too great for the surge protector(s) to handle. Using a "two-stage" surge protection system should protect against most of the power surges.
Why is it Better to Have a Two-Tiered Surge Protection System?
By combining a service entrance surge protector with point-of-use surge protectors located at all sensitive electronics, a better protection system is created.
Examples of Service Entrance Surge Protection Devices
There are service entrance surge protection devices that mount in or on your main electrical panel, or at the base of the electric meter. Several examples are shown below. Only one service entrance surge protection device is needed if it protects all incoming lines, including electrical, telephone, and cable TV lines. As an alternative, separate devices can be installed on each incoming line.
Point-of-Use Surge Protection Devices - an alternative to whole house protectors
There are also several types of point-of-use surge protection devices:
Point-of-use surge protection devices (plug-in type): You may be familiar with the plug-in type surge protectors. They look like plug strips, having several plug-in locations on one device. A regular plug strip, unless it specifically says so, does not provide surge protection. Be careful when buying such items to make sure that you are getting the surge protection you need.
Surge protection electrical outlets: Special electrical outlets contain surge protection in those places that you don't have room for or don't want a plug-in type surge protector, such as at a countertop microwave oven.
Surge Protection Terminology
Surge protection and the associated protection devices on the market can be confusing to a homeowner. Understanding the terminology can help.
Surge Protection Devices have several names: surge protectors, surge suppressors, transient voltage surge suppressors (TVSS), or secondary surge arresters. But they essentially have the same function of protecting against power surges. Other common terms you may hear when shopping for surge protection devices are listed below.Surge Protector: For the type of products one would find around the home, this a general term that can refer to TVSS or secondary surge arresters. These devices are designed to protect equipment "downstream" against power surges by reducing the amount of voltage they let through.
Many electric utility companies also use secondary surge arresters and devices called lightning arresters throughout their electrical grid to protect their equipment from lightning damage. The devices they use are more durable, but can't reduce the power surge down to the lower voltage levels that in-home products can.
However, the utility company's surge protection measures can help the homeowner by reducing the energy level of a power surge before it gets to the home.
Secondary Surge Arrester: These devices are designed to go on the inside or outside of the house. If tested, they are tested according to the recommendations of the Institute of Electrical and Electronics Engineers (IEEE) standard C62.11, Metal Oxide Surge Arresters for Alternating Current Power Circuits, with a 10,000-volt, 5,000-amp power surge. IEEE C62.11 is not a test and does not assign a clamping voltage for secondary surge arresters. This makes it difficult to compare the capabilities of one product to the next.
These devices include the meter-mount surge protectors and the plug-on surge protectors that snap into the electrical panel.
Transient Voltage Surge Suppressor: TVSSs are generally designed to go on the inside of the house. If tested, they are tested according to Underwriters Laboratory (UL) standard UL 1449 with a 6,000-volt, 500-amp power surge. UL 1449 assigns a clamping voltage to the TVSS which can be used for comparison from one product to the next. These devices include the point-of-use surge protectors and service entrance surge protectors mounted on the electrical panel.
Clamping Voltage: TVSSs should have a clamping voltage specified. Clamping voltage is the voltage at which a surge protector begins to work by redirecting the power surge to ground. The lower the clamping voltage of the surge protector, the lower it will reduce the power surge voltage.
UL 1449 2nd Edition: This is a test standard that was developed by UL in conjunction with industry to certify product ratings and ensure proper markings on TVSS products. Through this test, the clamping voltage is determined.
IEEE C62.11: This standard, written by the Institute of Electrical and Electronics Engineers, has recommendations on how to test secondary surge arresters. [IEEE C62.11: Standard for Metal-Oxide Surge Arresters for AC Power Circuits (>1 kV)]
Let-Through Voltage: This is the residual surge voltage that passes through a surge protector after the protector has "clamped" in response to the power surge.
Metal Oxide Varistors (MOVs): MOVs are a common technology (not the only type) and are at the heart of the surge protector's (TVSSs) ability to protect against power surges. Generally, the larger they are and the more there are equates to better protection and a more durable, longer-lasting surge protection device.
Thermal Fuse Protection: Because MOVs heat up when handling a power surge, there is a potential for the surge protection device or material surrounding the surge protection device to catch fire. The 2nd Edition of UL 1449 tests the fire safety of the TVSS surge protection devices by requiring severe overvoltage tests, causing the MOVs to fail.
L-N, L-G, & N-G Protection: The electrical system in your home is typically a three-wire system. The wires are the ground, line (hot), and neutral. A power surge can exist across any of these wires. The surge protection should protect against surges coming through any of these wires. When a surge protection device indicates the following, you know all wires are protected: Line to Neutral (L-N), Line to Ground (L-G), and Neutral to Ground (N-G). Secondary surge arresters installed at the service entrance have only Line to Neutral (L-N) protection because there is no ground wire in the locations where they are installed.
State Farm® believes the information contained in this article is reliable and accurate. We cannot, however, guarantee the performance of all items demonstrated or described in all situations. Always consult an experienced contractor or other expert to determine the best application of these ideas or products in your home.
Thanks to our friends at State Farm Insurance from allowing us to reprint this article.