Maybe you know this story: There’s a thunderstorm. Lightning strikes nearby. The power cuts out for a moment, then returns.
But when you try to switch on the TV, it doesn’t seem to work.
In the United States, power surges are responsible for hundreds of millions of dollars of property damage every year. Surges can instantly overload and short out the circuitry of home electronics. Over time, surges can also cause cumulative damage to your property, incrementally decreasing the lifespan of televisions, computers, stereo equipment, and anything else plugged into the wall.
Learning more about surges – what causes them and how to prevent them – can help save money and keep your property safe.
How Does A Power Surge Cause Damage?
In the United States, most homes use electrical power in the form of 120-volt, 60 Hz, single phase, alternating current.
However, the voltage is not delivered at a constant 120 volts. With alternating current, the voltage rises and falls in a predetermined rhythm. The voltage oscillates from 0 to a peak voltage of 169 volts. Most appliances and electronics used in the United States are designed to be powered by this form of generated electricity.
During a power surge, the voltage exceeds the peak voltage of 169 volts.
A spike in voltage can be harmful to appliances and electrical devices in your home. An increase in voltage above an appliance's normal operating voltage can cause an arc of electrical current within the appliance. The heat generated in the arc causes damage to the electronic circuit boards and other electrical components.
Smaller, repeated power surges may slowly damage your electronic equipment, too. Your computer or stereo may continue to function after small surges occur until the integrity of the electronic components finally erode and your television, cordless phone, or answering machine mysteriously stops working. Repeated, small power surges shorten the life of appliances and electronics.
Where Do Power Surges Come From?
There are several sources of power surges. They can originate from the electric utility company during power grid switching. A common cause of power surges – especially the most powerful surges – is lightning. Power surges can originate inside a home when large appliances like air conditioners and refrigerator motors turn on and off.
Power surges can enter a home through several pathways. In the case of lightning, it can take the path of the cable TV or satellite dish cable, through the incoming telephone lines, or through the incoming electrical service line.
How Can I Protect My Property?
Point-Of-Use Surge Protection Devices (SPDs), combined with a good grounding system, should protect your electronic and electrical appliances from most electrical surges. An SPD does not suppress or arrest a surge; it actually diverts the surge to the ground.
One familiar point-of-use surge suppressor looks like a regular plug strip. However, unless it specifically says so, don’t assume your plug strip offers surge protection.
You can also install special electrical outlets that offer surge protection. Surge protection outlets are useful in locations where there isn't room for a plug-in surge protector, such as near a countertop microwave oven.
The Two-Tiered Approach
Point-of-use devices can protect particular appliances in your home, but a more comprehensive approach to surge protection is to combine point-of-use devices with another device, like a service entrance surge protector or an electrical panel surge protector. By installing two tiers of surge protection, you’ll be able to protect your home from all but the most powerful surges.
Service Entrance Surge Protection Devices usually mount in or on your main electrical panel or at the base of the electric meter. Using a service entrance surge protection device provides protection for your entire electrical system; they protect things such as motors, lights, outlets, light switches, and all the other "hard wired" items in the house that do not plug into an electrical outlet and can't be connected to a point-of-use surge protection device. And if the power surge is created by a lightning strike or power fluctuation on the utility lines, the service entrance surge protection device can reduce the power surge to a lower level before it gets to the point-of-use surge protection device.
Service entrance surge protection devices will either be Transient Volt Surge Suppressors (TVSSs) or secondary surge arresters. It’s difficult to compare the capabilities of a TVSS to a secondary surge arrester because the two are tested differently. Consult an electrician for further advice on how to install a service entrance surge suppression device.
More To Consider
- Make sure any surge protectors you purchase are listed as UL Standard 1449. This is a national benchmark and means the product has been thoroughly tested.
- Select a point-of-use surge protector that has an indicating light and/or audible alarm to show when it needs a replacement.
- Look for SPDs that come with a manufacturer's warranty. Some warranties cover only the device; others also cover any damaged equipment connected to the device.
- Direct lightning strikes are powerful enough to overwhelm even the best surge protection; that said, the ultimate surge protection is to unplug equipment from the wall if you suspect a surge might be coming.