Power quality refers to the consistency of the electric voltage. Voltage outside the proper range can damage electrical equipment.
In years past, power was used to operate only motors and lights. Today, homes and businesses are filled with computers, televisions, stereos, appliances and other equipment containing microchips. These devices are extremely sensitive to the quality of power.
Problems with Power Quality
These are sudden increases in voltage that last less than 1/60th of a second. They can be small or large — up to thousands of times the normal voltage. Large spikes can burn or melt electronic components causing instant failure. Repeated ‘hits’ from smaller spikes gradually erode components and can shorten their useful life. Most spikes originate inside your home or business. Other electric equipment, such as refrigerators, copy machines, laser printers and large motors, can cause spikes when turned on and off.
A smaller percentage of spikes originate outside your building, caused by lightning strikes, short circuits in electric lines and large equipment used by factories. While these spikes are less frequent, they tend to be more serious. Lightning strikes to a telephone line, cable TV system or satellite dish also carry voltage spikes. Devices that are connected to more than one wire, such as cordless telephones, answering machines, computer modems and TVs are especially vulnerable
These are decreases in voltage that starve machine for the power they need to operate. This is the most common form of power quality problem. Sags usually last less than a second–voltage drops longer than one second are called brownouts. When power returns, spikes often occur as equipment in the system springs back into action.
These are a total loss of power which may last less than a second or up to several hours. You may not notice a split second interruption, but your computer might restart or your digital clock may start flashing.
Noises don’t cause much damage, but it can be a nuisance. You see electrical noise as ‘snow’ on the TV screen or hear it as static on the radio. Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) are two sources of noise.
A surge protection device is designed to reduce the magnitude of a surge, protecting equipment from damaging effects. Common types of surge protection devices include whole-house, point-of-use and uninterruptible power supplies (UPS).
Whole-house units are hard wired into the main circuit breaker panel by an electrician. This type of device typically has indicator lights that quit working if it has taken a surge larger than it can absorb. A hard-wired whole-house unit averages between $500 and $700 installed and can exceed the $2000 range for specialized electronic equipment.
The electricians listed below install whole-house surge protection devices.
Point-of-use surge protection devices are located at or near the equipment and have fax, modem, telephone and cable capabilities. Surge suppressors only work if they are plugged into a properly grounded 3-prong outlet. If your home has 2-prong outlets, have a licensed electrician upgrade the outlets.
UPSs are designed for computer use and allow enough time to exit files and turn off a computer. The devices include batteries that provide enough electricity to keep a computer system operating until it can be safety shut down, 10 – 25 minutes, depending on the device.
What features should you look for in a surge suppressor?
- UL 1449 listed — the unit conforms to Underwriter Laboratory’s standard UL 1449 for transient voltage surge suppressors — a requirement for safety
- Peak Impulse Current — sometimes called maximum surge or spike capacity — 39,000 amperes or more (higher is better)
- UL 1449 suppression rating – sometimes called clamping voltage — 330 volts gives the best protection (higher voltage ratings give less protection)
- Energy Rating — 420 joules or more (higher is better). Because testing methods for energy rating are not standardized, don’t base your choice on energy rating alone.
- Manufacturer’s warranty of at least five years
- Status or warning lights to indicate the device is working, not just that it’s on
- If you are protecting a TV, DVD/VCR player or computer, purchase a surge suppressor with TV cable connectors and/or phone jacks.