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Does an internet installation with a FiOS cable protect my system from possible lightning strikes?


Hi Leo. Many years ago, my phone line took a lightning strike, and for all
practical purposes, it vaporized my computer. I presently have a mirror raid
configuration with Win 7 X64 professional. I have FiOS service, everything
hard-wired, not wireless. It is installed with the FiOS cable from the utility
pole into my house where it is connected into the multiplexer/ONT (both
terms being used by the installer) and coax cable from that to the FiOS
router/modem, and ethernet to the computer. Question: With this FiOS setup, is
there any cause for concern about another lightning hit? I am not concerned
about the electric power supply line being hit by lightning: that is already
protected. It also has a constant voltage transformer in the computer and
peripherals circuits to prevent low voltage. Thanks.

In this excerpt from
Answercast #21
, I look at the protection that FiOS cabling might give to a
home. It depends on how thoroughly it’s installed.


FiOS Fiber Optic Cable

The “O” in FiOS stands for “optical.” One of the assumptions that people often make is that because it is an optical-based service, that the connection into their house is in fact is being made over fiber optic cable.

Sometimes, it is. But as I learned awhile back, more frequently, it’s not.

The fiber that it refers to may in fact only go as far as the street.

The connection between the street and your home (and obviously the rest of your computers) may in fact still be copper. It may in fact be wired.

Electric wires and lightning

What that means is that, ultimately, if you’re in a lightning strike prone area then, yes, there’s an electrical wire hanging outside your house connected to your computers… that could potentially take a lightning hit and transmit the electrical energy from that lightning hit upstream.

At some point, I would hope that the FiOS equipment installed by your installer will actually be set up in such a way to be able to protect you from that. I’d want to confirm that with the installer for sure. But ultimately from our perspective, looking at it from the inside of the house, yea, you’ve probably got wires.

You probably have something that you want to protect yourself from, if this is in fact a lightning strike prone area in which you’re living.

I, for example, here in the Pacific Northwest, (at least where I live) just don’t get lightning strikes all that often. Certainly nowhere near the house, so it’s not something I would be concerned about. But in other areas of the country (or other areas of the planet), lightning is significantly more frequent, more common, and can cause more problems.

I would absolutely look at protecting yourself from it.

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7 comments on “Does an internet installation with a FiOS cable protect my system from possible lightning strikes?”

  1. My self i have surge protectors and other stuff to protect my computer from lightning strikes. Still i feel safer unpluging everything at the first sign of bad weather.
    It takes me about 1 minute to unplug everything. Like the old saying goes, “It’s better to be safe than sorry”
    I can live without using the computer or internet for a few hours. It’s better than having to go buy new parts or a new computer.

  2. If Leo permits, I’m going to take this opportunity to impart a little basic science lecture. Unplugging your computer during an electrical storm amounts to little more than throwing salt over your left shoulder or some other silly superstition. There may actually be some rare coincidence when it actually does some good, but about as likely as hitting the lottery jackpot.

    First, for those pathetic little “surge protectors” in power strips, they’re cheap “dozen for a dollar” components that are meant to work for power line spikes that hit 175 volts. A billion volt strike that travels 4 miles of open atmosphere is not going to be stopped by a half-inch of insulator between your power line and computer. That’s why the cable company, the phone company, the satellite company, HOWEVER you get your internet, installs a grounding wire outside your house. A lightning strike wants to go to ground, pure and simple. It prefers a short distance down a piece of wire than having to travel throughout your house’s electrical wiring to find a device to eventually get it to ground.

    Second, if it can affect your computer, it can affect every single appliance plugged into your home. Your TV, your DVD player, your refrigerator, washer/dryer, and electric oven are all subject to destruction. That’s why you have insurance. If no insurance, there’s much more than the loss of a computer.

  3. @Mike, If you unplug a device from the outlet, that device is absolutely, positively protected from a lightning strike. It is much, much better than “throwing salt over your left shoulder”. Once the device is unplugged, a lightning strike will not jump across the air gap between the outlet to the plug of your computer. Lightning will not jump the gap because the computer is no longer “grounded” and there is no low impedance path to ground through the computer. This is the same situation that you have when you see birds on a high voltage overhead distribution line. The bird is not killed because it is not grounded, and no current flows through it. As you stated, lightning will follow the path of least resistance to ground. That path will be via other connected devices in your home, or by jumping from the hot prong across the air gap at the outlet to the neutral prong or the ground prong of the outlet that you just unplugged your device from.

    I agree that if all you do is unplug your computer, but you leave your TV, stereo, DVD player, etc. plugged in, then all of those other devices are still at risk. However, if you unplug those devices too, they will also be protected.

    Peter Mackin

  4. Mike: If a computer is completely unplugged (both power cord and internet cable), I don’t see how you can say it’s not safe from a storm. Also, an electronic device dealing primarily with data, would seem to me to be a lot more vulnerable to damage from a power surge than say a washing machine.

  5. In RI, the fiber stops in the basement or the Ont. Then the old cox cable wire is reused. I do not unplug the bbu.

  6. Verizon Fios does bring the glass right into the house and connects it to the ONT.

    Thus the glass is not a conduit for a lightning strike like copper is.

    However, that doesn’t help you much. Your real problem is all of the wires that are connected to your computer or other electronic device.

    Let’s suppose that your house or the wiring coming into the house is struck directly by lightning.

    If it is the wiring coming into the house a good portion of the charge will be directed to ground but with lightning there is so much electricity that it will likely take multiple paths to ground.

    If the house is struck, the lightning will find the housewiring and use it as the main paths to ground.

    Other paths will likely be anything with a wire attached. Even if the path doesn’t lead directly to ground, it makes the path shorter.

    Thus your computer and electronics are likely to be damaged if they are connected to almost anything via a wire or cable.

    Thus, unplugging your computer only from power is incomplete protection. You really need to pull the power cord out of the back, unplug the ethernet cable, and unplug any USB devices as well. Don’t forget your display.

    By the way, everything conducts electricity, if you get the voltage up high enough. Everything has a breakdown voltage where it goes from insulator to conductor and when that happens whatever it is is usually destroyed or severely damaged.

    In the case of a wood house, the wood usually catches fire.

  7. Lots of good comments. I think that if I were in Florida I would take many of the steps suggested in the other comments.

    In addition I would use 802.11N instead of wired ethernet. That will eliminate one path for lightning to get into every device on the network.

    For external drives I’d consider 802.11N network attached storage.

    I use a notebook as my main computer now but I do have several desktops. I’d probably phase out all of the desktops and rely on notebooks which are easier to disconnect from everything.

    Anything that is not attached to any wires is as safe as it’s going to get.

    Thus by going with notebooks and 802.11n as well as using wireless NAS instead of any file servers you have everything divided up as much as possible. The only common denominator being power.

    Of course, I’d also use a wireless printer.

    So, as a matter of course, the notebooks could be left off and disconnected when not in use and there is a potential of storms. When needed for use they simply need to be plugged into power and turned on.

    The cable/dsl modem and router will be vulnerable but they are relatively inexpensive and do not contain your data so I would probably have them on a battery backup so I could use the internet if the power went out and if they were damaged I’d deal with it after the storm.

    Up this way, the cable internet doesn’t go down when the power goes out. At least not right away. There is usually several hours of backup to the system.


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