Surge protectors are a common staple in just about every house that has a computer or expensive electrical equipment that needs protecting. They come in a variety of shapes, sizes and power ratings, which claim to protect the equipment should a power surge occur. And while that may be the case for smaller variances in the electrical grid, will they really protect equipment from a lightning strike, the grand daddy of all electrical surges?
The short answer is, no.
Small appliances and equipment use small fuses, which when exposed to an over-voltage or large power spike melt, thus breaking the electrical circuit by creating an air gap of just a few centimeters. This is enough to stop the electricity from flowing and the 120 volts is unable to arc across the air gap. Once the fuse blows, the old one is removed and a new one is inserted, allowing electricity to power the device.
Over the last few decades, fuses have been replaced by circuit breakers and reset buttons, that when exposed to the same power surge, trigger a re-settable switch into the open position, also creating an air gap of just a few centimeters. All one has to do is press the reset button which allows electricity to flow again. This is far more convenient than keeping a stock pile of fuses of various sizes and amperage.
But are a few centimeters really enough to stop a lightning bolt that can be hundreds of thousands of volts? The voltage of a lightning bolt will not only blow the circuit breaker, but it will also jump the small air gap of a few centimeters. A lightning bolt travels miles upon miles through the air, which in itself is an air gap between the cloud above and the ground below. If an air gap of three or more miles isn’t enough to stop a lightning bolt, neither is a surge protector. The electricity in the lighting bolt is far too great.
When a house gets struck by lightning, the electricity rarely follows a single path. It will flash to other conductors like copper piping, electrical wires, telephone lines and coax cable lines. Moreover, the amount of voltage is so extreme, it will blast through a solid wood roof, drywall or even concrete to find the earth-ground. A small little surge protector is not going to stop this kind of electrical madness! And if the electricity doesn’t get your equipment, the fire that ensues most likely will.
The only way to achieve some level of protection against lighting is with a whole-house lightning mitigation system, but even that won’t guarantee the safety of your electronic equipment. One could also look at a whole-house lightning suppression system that attaches to the main service panel, but this too will not provide 100% protection, and they can be quite expensive.
The absolute best way to protect your equipment is to simply unplug it from the wall if a thunderstorm is nearby. Once unplugged, the equipment is no longer tied into the electrical wiring of the house or a common grounding system. Therefore, the likelihood of the lightning’s electric current arc flashing to the equipment to find “ground” is extremely remote.
However, power strips and surge protectors do in fact greatly help against power surges that originate from electric companies. These types of surges are much more mellow in comparison to a lightning strike. They are also fairly common, so surge protectors are a worthwhile investment. Especially for expensive electrical equipment.
Don’t be mislead by the packaging that shows lightning bolts hitting a house. All surge protectors provide protection up to a certain level, usually around a few thousand joules. Since a lightning bolt exceeds 4 billion joules, you will not be reimbursed for any damages if your house takes a direct hit. The surge protectors limited warranty only applies when a surge under the stated rating occurs and the surge protector failed to operate correctly. I’ve seen what happens to a house when it gets hit by lightning and nothing survives.