Will lightning zap my modem?

Darzian · Oct 26, 2008

I'm getting conflicting reports so I thought I'd ask. Most telephone cables run above ground here, and it's been raining 12 hrs a day and I'm going nuts keeping the modem disconnected for fear of a lightning strike. The trip switch to the house's main power already fell thrice.

Can lightning truly zap a modem in use? (Its DSL)

Del · Oct 26, 2008

Yes! Absolutely

A strike anywhere along a metal electricity conducting line will send a jolt to all that is connected to it. That means your modem and the whole darn computer.

I imagine with optical lines the risk has become a lot less but the lines into and through your house are still metal and lightning loves metal.

In use and not in use. High voltage can jump yards.

benbradley · Oct 26, 2008

Yes, and it really doesn't matter much if it's turned on or off. And even if the cables were below ground, that would only reduce the chance of a lightning strike taking out the modem, not eliminate it. Unplugging the phone line going to it will save it from all but the worst strikes (such as lightning striking the house). To protect it from that, you should unplug ALL the cables going to it.

There's also the danger of lightning striking just as you unplug the cable (you don't have to touch the terminals, if lightning strikes while you're holding the cable, it may well get to you), so you may want to consider that too.

astonwest · Oct 26, 2008

Yes! My former computer is living proof...lucky it didn't take out anything but the modem itself.

I still unplug all of my computers when a thunderstorm rolls through.

Old Hack · Oct 26, 2008

Our phone line comes in underground and we've lost four dial-up modems in two years to lightning--even when the storm wasn't anywhere near our house, and the computer wasn't switched on but WAS plugged in still.

If there's lightning anywhere near our house (that is, within ten miles or so) I unplug the computer or look forward to another £20 modem.

Del · Oct 26, 2008

Old Hack said:
Our phone line comes in underground and we've lost four dial-up modems in two years to lightning--even when the storm wasn't anywhere near our house, and the computer wasn't switched on but WAS plugged in still.

If there's lightning anywhere near our house (that is, within ten miles or so) I unplug the computer or look forward to another £20 modem.

many surge protector power strips have a plug for the phone line too. Helps in less sever instances.

Don't for get to unplug the phone line too.

regdog · Oct 26, 2008

You can also be shocked through your computer if you're using it during a thunder and lightning storm.

Bravo · Oct 26, 2008

true story:

a few years ago, i unplugged my old computer and plugged in my spanking new desktop. i was in the process of putting the old computer in a different room when

BOOOM!

lightening smashed into one of our balconies, the lights went out for a bit and the new computer died.

i was this close to wiping out everything on my old computer, not to mention the fact that it's warranty had expired.

this close.

phew.

i should still be shaking over this.

Darzian · Oct 26, 2008

I'm so glad I asked this.
I'd no idea it had happened to so many people!

What I currently do is this:

1) Black sky, distant thunder.
2) Immediately pull out the telephone cable from the modem and place it around 1 metre away from the modem.

That should be the max I could do, right?

I continue to use the computer normally though. I love working on my WIP through thunderstorms. The house is protected, so a lightning strike will just cause the trip to fall, and all power gets shut off till I go and turn it back on. The computer shuts off too, but my autosave is set, and I can't be bothered with a UPS. The last UPS I owned NEVER kept my computer running during a power cut.

We're having the monsoon now- several hours of rain a day.

Del · Oct 26, 2008

Darzian said:
I'm so glad I asked this.
I'd no idea it had happened to so many people!

What I currently do is this:

1) Black sky, distant thunder.
2) Immediately pull out the telephone cable from the modem and place it around 1 metre away from the modem.

That should be the max I could do, right?

I continue to use the computer normally though. I love working on my WIP through thunderstorms. The house is protected, so a lightning strike will just cause the trip to fall, and all power gets shut off till I go and turn it back on. The computer shuts off too, but my autosave is set, and I can't be bothered with a UPS. The last UPS I owned NEVER kept my computer running during a power cut.

We're having the monsoon now- several hours of rain a day.

Your computer can be zapped if it is plugged in. Battery power on a laptop is okay if you turn off the wifi adapter (no risk to the computer but electricity makes massive frequencies and you could blow the adapter) but if you are on the grid in a thunderstorm you are risking your computer and your data. 10s of thousands of volts do not play well with devices designed to run on 5.5 volts. Unplug everything.

Darzian · Oct 27, 2008

omg, no computer?

I can't take this!!!

Pagey's_Girl · Oct 27, 2008

My father told me that a UPS would protect my computer from lightning. I made the mistake of listening to him. Luckily it only took out part of the hard drive and I didn't lose too much. Now I unplug everything.

Del · Oct 27, 2008

I have an APC Battery back up. It is a surge protector like no other but I unplug it and can run for hours on its batteries.

If you are off the grid you are relatively safe.

Williebee · Oct 27, 2008

Don't forget to disconnect any speaker power, too.

Surge protectors and APC Backup's are a great idea. Take the time to hook up the USB and learn how to program it to shut down your computer in the event of a power failure. It only takes about 20 min. or so, and is more than worth it.

Darzian · Oct 27, 2008

My house has a trip switch for the entire household. A slight surge and it falls, automatically cutting off power. It happened at least thrice this week. I've never lost an appliance to lightning. I believe that the trip switch safeguards from potential lightning through the electric cables?

Fenika · Oct 27, 2008

regdog said:
You can also be shocked through your computer if you're using it during a thunder and lightning storm.

Been there, done that, and my hand was hovering over the keypad. The precious laptop was unscathed. Miraculously.

Del · Oct 27, 2008

Darzian said:
My house has a trip switch for the entire household. A slight surge and it falls, automatically cutting off power. It happened at least thrice this week. I've never lost an appliance to lightning. I believe that the trip switch safeguards from potential lightning through the electric cables?

Standard breakers most likely. They'll trip in a surge but not fast enough. You cannot stop lighting with a trip switch. It has to be suppressed. Even then you will only suppress a small jolt. Never a direct hit or even a near hit.

A breaker works from heat. It is designed mostly for overloads...too many things plugged into a receptacle. If you resolve the overload you have to physically go reset the breaker. Turn it off, turn it on.

Power off and on by itself is the grid trying to protect and correct itself. This is of no help to you or the things in your home. It is in fact somewhat harmful because any off/on with electricity causes a power surge. The more devices you have coming back on at once the bigger your surge. Power failure? Turn off anything you were using. Lights, TV, etc. If you ever seen power flicker...it is because the grid is trying to recover with too many things coming on at once and is drawing too many watts. 10,000 TVs is quite a bit of extra power to flick on all at once.

Best policy is unplug things like the TV and computer in a storm. A refrigerator is just a motor and is pretty hearty but fine electronics work on millivolts and popping a simple resistor can render the entire device useless.

Ali B · Oct 27, 2008

I had lightning fry my modem and my hard drive on my laptop. I had a surge protector on both and it still fried.

Darzian · Oct 27, 2008

Delarege said:
Standard breakers most likely. They'll trip in a surge but not fast enough. You cannot stop lighting with a trip switch. It has to be suppressed. Even then you will only suppress a small jolt. Never a direct hit or even a near hit.

A breaker works from heat. It is designed mostly for overloads...too many things plugged into a receptacle. If you resolve the overload you have to physically go reset the breaker. Turn it off, turn it on.

Power off and on by itself is the grid trying to protect and correct itself. This is of no help to you or the things in your home. It is in fact somewhat harmful because any off/on with electricity causes a power surge. The more devices you have coming back on at once the bigger your surge. Power failure? Turn off anything you were using. Lights, TV, etc. If you ever seen power flicker...it is because the grid is trying to recover with too many things coming on at once and is drawing too many watts. 10,000 TVs is quite a bit of extra power to flick on all at once.

Best policy is unplug things like the TV and computer in a storm. A refrigerator is just a motor and is pretty hearty but fine electronics work on millivolts and popping a simple resistor can render the entire device useless.

Thanks for the advice. It's invaluable. Yes, after the switch falls I do switch off all the sockets before putting the power back on. Then I go around turning on all the sockets one by one.

This has been a very good discussion. Thank you all.

L M Ashton · Oct 28, 2008

Darzian, the other thing is that you really should use a power stabilizer as well, given the blackouts, brownouts, power surges, and whatnot we have with electricity here. Even the very very frequent brownouts can cause damage to electronic devices.

In all honesty, we have a power stabilizer, UPS with stabilization, and a surge protector in a line before electricity even reaches our computers.

And, yeah, y'all, Darzian ain't kidding about the hours and hours of downpours.

My lawn is green again.

SPMiller · Oct 28, 2008

At one time, I believed network hardware was immune to lightning strikes. After all, network cables aren't designed to carry power, just the data signal. However, experience has taught me that hubs, routers, and NICs can all be knocked out during storms, even if you use surge protectors. The only sure way to save your hardware is to completely disconnect every component from every other component. Annoying.

I have a suspicion that close lightning strikes will induce current in network cables.

Darzian · Oct 28, 2008

L M Ashton said:
Darzian, the other thing is that you really should use a power stabilizer as well, given the blackouts, brownouts, power surges, and whatnot we have with electricity here. Even the very very frequent brownouts can cause damage to electronic devices.

In all honesty, we have a power stabilizer, UPS with stabilization, and a surge protector in a line before electricity even reaches our computers.

And, yeah, y'all, Darzian ain't kidding about the hours and hours of downpours. My lawn is green again.

I used to have a UPS. It never helped for some reason. Thankfully, the blackouts have almost disappeared in the last 5 years. 5 years ago it was terrible.

The rain relented today.

But the air was so dry I had to pull the water dispenser over to the computer desk. God, I'm almost waiting for the rain. The heat's even worse!!!

regdog · Oct 28, 2008

Bahamutchild said:
Been there, done that, and my hand was hovering over the keypad. The precious laptop was unscathed. Miraculously.

Yeah, thank goodness you weren't hurt

L M Ashton · Oct 28, 2008

Gee, we have days where the power goes out a half dozen or a dozen or more times. Sometimes it's for a second or two, but still. Unless you're talking about the daily blackouts because of water shortages? Yeah, I haven't been through that, thankfully.

And we still have a lot of brownouts mixed in with the blackouts.

Will lightning zap my modem?

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