Power Issues: Brownouts, Blackouts & Surges
Brownouts, blackouts and surges are three of the most common power issues. To protect against their potentially damaging effects, let’s look at common causes, risks they pose and actions you can take.
Brownouts or power sags occur when there are temporary drops in the power supply. These drops may cause lights to dim or flicker and appliances and computers to hiccup.
Controlled brownouts are deliberate reductions in voltage implemented by power utilities in response to problems with the distribution grid or excessive demand that threatens to overload the system. In a controlled situation, the utility typically reduces voltage by 10% to 25% to prevent a complete outage. Uncontrolled brownouts occur without warning when demand exceeds supply, creating a brief voltage drop.
Brownouts may last a few minutes or a few hours. Most standard appliances are designed to function normally on 115 to 125 volts so they can withstand these variances, but computers and electronic devices are more vulnerable. To reduce the risk of damage and help prevent an outage, shut down all electronic components and turn off as many lights and appliances as possible.
Blackouts occur when power is completely disrupted, creating an outage. Unplanned blackouts may be caused by animals, car accidents, human error, power equipment failure and severe weather.
Planned or rolling blackouts are controlled outages implemented by utilities to offset excess demand, system problems, or maintenance and repair activities. They are usually announced in advance, last 30 to 90 minutes and are staggered across service areas in a region.
Severe storms tend to cause more extended blackouts, since damage is widespread and sometimes difficult to access and repair. In spite of this, power companies are often able to restore power to 60% to 80% of customers in about 48 hours, but it may take 10 days or more to finish restoring power to the rest. To ensure a steady supply of electricity during rolling blackouts or power outages, invest in an automatic standby generator.
Surges or spikes occur after something disrupts the power supply. While many surges are imperceptible, some cause lights to dim or brighten.
External surges may be caused by tree limbs brushing a power line, lightning striking equipment or animals getting into transformers, but they also occur when power is restored after an outage or controlled blackout. Internal surges happen when power-hungry equipment such as furnaces and central air conditioners turn on.
You can safeguard sensitive electronics by using surge protectors. To protect your electrical system from external surges, have a whole-house surge suppressor installed at the main panel, but continue to use individual protectors to defend against internal surges