Router always catches fire during thunderstorms? I burned a whole set before I figured out that the thunder comes in through these three openings

a thunderstorm night in July two years ago, I woke up the next morning with no WiFi. The optical modem has no lights at all, as if the power is out; The router was still on, but plugging the WAN port into the network cable didn't respond at all. The LAN port was still working, half the machine was still alive; The Mercury five-port switch inside the weak current box, four ports are normal, and one port is completely dead. A set of equipment was combined, and replacing them all cost nearly 600 yuan. After chatting with the installer for half an hour and flipping through a bunch of materials, I finally understood: most equipment burns aren't struck by lightning directly into the house, but by induction lightning that jumps in along the . This article will clearly explain the three types of lightning outlets that allow lightning into the house, whether lightning protection power strips actually work, and how to remedy a real fire.

first understand: lightning is not a slashing device, but rather a rush along the line

The essence of lightning is a massive instantaneous current, and the magnetic field in the surrounding space changes dramatically at the moment of discharge. Any metal wire in your home—power cord, network cable, even the steel wire in the optical fiber—will be "sensed" like a receiving antenna, generating instantaneous high voltage of thousands to tens of thousands of volts. This high-pressure line runs into the house, burning whoever it encounters, and only stops when the energy is exhausted or enters the ground. That's why families struck by lightning often end up the optical modem, router, and switch all connected together: the surge comes from a single cable, first passing through the optical modem, then running along the network cable to the router, then to the switch, and all the way through.

specifically when it comes to home networks, Lei enters the house through three channels:

many people think, "I have fiber optic in my home, it's non-conductive, safe"—but that's only half true. Fiber optic does not transmit lightning, but the modem's power plug is still plugged into 220V, and the metal network port is connected to a piece of metal equipment, so not a single cable is lost.

lightning protection power strip is useful, but don't expect it to withstand lightning strikes

After burning out a set, my first reaction was to buy a lightning protection power strip. To start with the conclusion: lightning protection strips costing just a few dozen yuan are effective, but lightning protection against direct strikes is useless. This isn't about buying expensive or cheap—it's determined by principle.

the core component inside a lightning protection power strip is the varistor (MOV), which in plain language is a "voltage valve": when the voltage is normal, it does not move; once an abnormally high voltage rushes in, it instantly conducts to dissipate the excess voltage, leaving the remaining voltage at the device side low. Reputable lightning protection power strips on the market can reduce the surge residual voltage of 6000V to around 1500V, so most small appliances and adapters can be preserved. Its fatal weakness is capacity—the energy of a direct strike can be tens to hundreds of kiloamperes, and the vastor's body is instantly penetrated, burning itself along with it. Therefore, lightning protection power strips are only last terminal line of defense in the lightning protection system. In front, there are building lightning protection belts and distribution boxes as major barriers, which are only responsible for final cleaning.

there are three key points to consider: first, look for the enclosure printed with "Surge Protection" or SPD and the maximum discharge current parameters (a household standard around 10kA is sufficient); Second, don't buy the 9.93 yuan varistor without a model. The varistor quality is poor, it ages and fails after a single surge and you can't tell it's already dead; Third, the socket should be plugged into three-hole with a ground wire, which will be discussed separately below. Later, I installed a Bull lightning protection strip for both the weak current box and the TV wall, 59 yuan each, and I've used them for two years without any issues—though maybe there hasn't been any real surge in those two years. Installing lightning protection doesn't mean it doesn't mean it doesn't mean it's a good thing, but if you don't, you'll definitely regret it.

grounding is the root of lightning protection, yet it's the easiest to overlook

and this is the biggest pitfall I've ever made: lightning protection power strips and network cable lightning protectors—the principle is to 'release surges into the ground.' If your outlets don't have reliable grounding wires, they won't leak out, which is like installing a decoration, but residual pressure still gets applied to the equipment. And in houses where the equipment is burned by the wave, nine times out of ten, the ground line is missing. How do

know if your home has ground wires? Buy a socket detector for just over ten yuan. Plug it into a three-hole socket, and the indicator light combination will tell you "correct," "missing ground," and "neutral and live reversed." In old houses, two-hole sockets only have neutral live wires, so there's definitely no space; Buildings after 2000 theoretically have them, but it's not uncommon for electricians to cut corners during renovation and not connect the connection. For self-built houses, you have to install grounding piles yourself. I wrote about this issue in my article on self-built housing network planning .

another easily missed item: the metal reinforcement core inside the fiber optic cable. The installer should have grounded it during installation, but many just cut it off for convenience. If your home has frequent thunderstorms and an empty area, proactively suggesting "Strengthen the core to ground me" during installation or repair, the technician will probably not do it if you don't mention it in two minutes. How to coil a leather cable into a weak current box, and what is the bending radius? I wrote about it in the article the optical modem to reposition. If the cable isn't good, lightning won't come before the light degradation comes first.

outdoor network cables are the hardest hit areas. Anyone who has installed surveillance cameras needs to check

If you only have the fiber modem router running around the house, the risk is actually manageable. The real hardest-hit areas are households with outdoor network cable : several cameras in the yard, a cable from the garage to the main building, a multi-floor cascade in a rental apartment—these cables can be walked for over ten meters outdoors, and during thunderstorms, they become receiving antennas. Later, when I installed surveillance planning in the yard ( the monitoring network planning had a complete plan), I specifically addressed this part.

have two tricks to deal with outdoor network cables. A cheap trick is to connect a RJ45 network cable lightning protector the device side. It costs tens to a few dozen yuan. Connecting one on the camera end and one on the switch side is more stable. When buying, make sure to use gigabit specs, or your camera will be dragged back to 100Mbps despite having a gigabit port. Similarly: network cable surge arresters must also be grounded. Their casing has a grounding terminal or wire. Don't mind the hassle and don't connect it—if you don't, it's like buying it for nothing. The real solution is to use fiber optic for the cross-building and yard sections—a pair of photoelectric transceivers costs dozens of pieces, glass is inherently non-conductive, so there's no way to pass through the wire, and the transmission distance isn't limited by the 100-meter limit (I calculated the network cable distance in the article on 100-meter network cable ).

another detail: the POE switch comes with an outdoor camera, and the outdoor device has a metal casing and lightning protection socket—these two features are truly impressive. Last year, during a thunderstorm, the neighbor's house was just a camera that came in, and they took away the POE port and a NAS port with a built-in NAS port. If the NAS didn't have a UPS with surge protection, the losses would have been even greater—but that surge protection on the UPS only handles induction lightning. When it hits a thunderbolt, you still have to remove it. I mentioned this clearly in my NAS UPS section.

really catches fire: the optical modem can be free, but the router is unlucky

no matter how well it is prevented, it still gets caught. There are two types of aftermath.

optical modem: Get a free exchange with your carrier. Optical modems are the operator's asset and are rented to you for use. They are obligated to replace them without human damage. The lightning strike was an accident, so I directly called customer service to request repair (Telecom 10000, Unicom 10010, China Mobile 10086), clearly stating that "after thunderstorms occur, the equipment loses power." The technician came to inspect and confirmed it was lightning strike, and replacement was free of charge. A friend's FTTR optical modem was damaged by the surge. After reporting a fault, he replaced it for free and waited three days. The only thing to be careful about is that in some regions, when you upgrade, they might even tie you a new contract or change your plan. Before installing, just ask, "Do I need to pay extra for equipment replacement? Does it affect my current plan?" Don't just turn it into a loan for free.

routers and switches: basically no warranty coverage. lightning strikes are considered force majeure under the warranty terms and are not covered by the warranty. If after-sales disassembly shows lightning strike marks (power chip shattered, network transformer burned), the warranty is immediately rejected. So these two are pure losses; the value of prevention lies here—a 59-yuan lightning protection strip protects a 300-400 yuan router plus all the devices inside.

As for the old topic of whether to unplug the power during thunderstorms, here's my fairness: new residential communities and buildings in the city should be properly grounded during thunderstorms, so don't scare yourself; In empty rural self-built houses, old residential communities, and right next to wilderness, during the half-hour of severe thunder, I unplugged the power supply and main network line from the optical modem router. Only when both were unplugged counted — even if the power supply was unplugged without the network cable, lightning would still come in through the network port. Now, every year before summer begins, I do a fixed procedure: check the grounding wire with the socket detector, check if the lightning protection power strip is still alive, and check if the grounding of the outdoor surge protector is loose.

follow the order, don't waste money

just give a final order, and follow the order from top to bottom. If you don't do the earlier ones, buying later ones will be wasted:

The awkward part of lightning protection is: if you spend money, you might never need it for a lifetime; if you don't, you end up with a whole set of equipment. My suggestion is to do the first two free steps first, then spend just over a hundred to complete the third and fourth steps. No matter how you calculate it, it's not a loss.