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What Is A Power Surge And Why Do They Happen?

If you are familiar at all with home electrical systems, then you are no doubt familiar with the concept of a “power surge.” They are also sometimes (but not often) referred to as “power spikes.” As you can probably tell from the name, a power surge occurs when a sudden spike of power is sent through a home electrical system, it can overload the electrical system. The problem with power surges is that they can actually damage any sensitive electronics that are hooked up to the electrical system. Typically electronics have measures in place to prevent being damaged by sudden surges of high voltage electricity, but the voltages generated by a power surge, that they easily break through those protections. Many of you will have heard of a “surge protector,” for those who have not, it is the primary method for protecting your electronics from damage by a power surge. If you are interested in getting a surge protector, we have done posts on things that people should know before buying a surge protector, as well as a post on the various kinds of surge protectors. However, we have not gone in depth on what actually causes a power surge. So, to help people get a better grasp on this somewhat common household electrical problem, we are going to explain what exactly causes a power surge to happen.

Two types of power surge

Power surges, or rather the causes of power surges, can be roughly divided into two groups, internal and external.


Internally caused power surges are power surges that originate within the electrical system. So for example, probably one of the bigger causes of power surges is the sudden start of a power heavy device or appliance. Some appliances like refrigerators, freezers, motors, etc., are such power hogs that even starting them can sometimes cause a huge power surge. Because these appliances require so much power, starting them cause the electrical system to have to work overtime to supply them with power (in addition to supplying everything else in the house), in addition to putting a lot of strain on your electrical system, it can also lead to a devastating power surge. It should also be noted, that we are not just talking about huge appliances like refrigerators and motors, but small, power heavy appliances as well. Even normal, everyday appliances like blow dryers and even microwaves can use enough power to cause a power surge. If you regularly operate power heavy appliances, it is recommended that you call a licenced electrician and get those appliances put on their own power circuit, to minimize the effect that the appliance will have on other parts of the electrical system. Now obviously, every time you turn on one of these power heavy appliances, a power surge is not going to occur. But, if a power surge does occur, it will be devastating, so it is best to prepare, even though the actual chances of a power surge are low.


External power surges are power surges caused by an outside influence negatively influencing your electrical system. The most common cause of external power surges, are inclement weather, namely lightning. As you can imagine, lightning contains a huge amount of electrical power. So, if by chance lightning somehow strikes your house, or enters your electrical system some other way (say by striking a power line) it can cause a massive power surge. Lightning strikes are especially devastating to electronics, and a single poorly timed lightning strike could potentially damage or destroy thousands of dollars of sensitive electronics. Think about how many expensive electronic devices you have hooked up to a single outlet, many people have a television, a gaming console, a speaker system, and a computer all hooked up to a single outlet, now imagine a single power surge damaging all those electronics at once. It is no wonder people are willing to invest so much money in expensive surge protectors. The only way to protect yourself from lightning strike induced power surges is to either turn off all your electronics every time a storm happens, or to invest in a couple of good surge protectors.


Another, less common, source of external power surges is power outages; but more specifically, the aftermath of power outages. When a power outage happens, all power running to your appliances is cut, and all your appliances stop working meaning they are no longer drawing on the electrical system. When the power comes back on, all those appliances immediately start demanding power, usually all at the same time. This sudden demand for a huge amount of power can cause a power surge. When the power goes out, it is generally a good idea to turn off all your appliances, and then manually restart them when the power company informs you that the power in your area has been restored.

What to do about it

If all this scares you a bit, it should. As we stated above multiple times, power surges can be devastating to your electronics, and a single, poorly timed power surge will end up taking a huge bite out of your wallet (assuming you do not have any protection). While you do not have to run out right this second to buy a surge protector, it is a good idea to begin researching them, and picking a surge protector that works for you. Some surge protectors are easy to install, and just need to be plugged into an outlet. But, in our opinion, if you want the best protection possible, then you need an electrician and get a surge protector installed directly into your electrical system, this will protect your entire house from power surges, as opposed to just protecting a single outlet. Of course more protection is always good, so if you can, get a surge protector installed in your electrical system, and then supplement it with more surge protectors installed on certain outlets that have a large amount of important electronics hooked up to them.