Electrical appliances will, of course, stop working if the power goes out. This is inconvenient but not necessarily harmful. When electrical power comes back after an outage, it goes through a surge condition. This “tidal wave” of electricity can damage appliances left turned on.
During normal electrical conditions, appliances use electrical current according to their purpose and rating. The AC line voltage is normal and stable, and the motors, heaters and electronics in an appliance behave the way they were designed. The appliance uses a nominal amount of current.
When the utility restores power to an area, the wires, which were empty of electrical current, experience an inrush called a surge. During the surge, electricity flows in rapidly to fill the empty wires. Momentarily, the current flowing in greatly exceeds the nominal current that appliances were designed to handle.
The line voltage can surge when the current does, spiking the normal 220 volt line with 200 volts or more for brief periods. This can happen after blackouts, from lightning strikes, or for other causes. Severe voltage surges can damage or destroy most electrical equipment.
If the power goes out for an extended time, switch off or unplug electric lights and any appliances, including computers, televisions and refrigerators. When the power comes back on, let the electricity stabilize for a few minutes before turning appliances back on. For computers and expensive electronics, invest in power strips with surge suppressors or similar protective equipment.
You can also invest in surge protectors ahead of time. Some power bars come with built in surge protectors, and it’s a good idea to use these especially in places like your entertainment unit and office where your electronics are being used.
Another option is to have a professional electrician come and install a whole house protector. This type of surge protector is typically wired into your service panel or fuse box. While it is a more expensive option, it can save you thousands of dollars in by protecting your appliances, and it can also give you peace of mind, which is hard to put a price on.