Lightning strike on cable internet

[Berty100]

For the second time in less than a week a lightning strike hit the coaxial cable that provides my internet.

I have a cable modem and router separately provided by the company.

In both cases it killed the router instantly, first time the WAN port and today the LAN port that was connected to my network switch, but the cable modem survived both strikes.

The company replaced my first router without questions, and I can only hope they will do same this time, but at the same time in both events a LAN port of a small switch somewhere along the network is killed as well.

It is a 5 port switch and now 2 LAN ports, which previously connected to the main network switch, are dead.

I will of course have difficulties to get that switch replaced by the cable tv company, and worry that in the future such a lightning strike will do more damage.

Is there a way to prevent this?

Take note the lightning strike was both times on the internet cable, and not the mains, since all electrics stayed on and only the internet died taking the router with it.

Edited November 14, 2015 by Berty100

[SoiBiker]

There are surge protectors available with cable coax connectors - I know Belkin make one. Maybe that would help?

[ubonjoe]

Perhaps a lightning/surge protector on the incoming cable. Perhaps one similar to this one. http://www.l-com.com/surge-protector-f-female-to-f-female-0-3-ghz-90v-lightning-protector

[Berty100]

Perhaps a lightning/surge protector on the incoming cable. Perhaps one similar to this one. http://www.l-com.com/surge-protector-f-female-to-f-female-0-3-ghz-90v-lightning-protector

I think that is indeed what I need. Will ask the cable company if they want to provide one, as it cost them a router each time, and otherwise have a look on Ebay.

[Pib]

Make sure True installed a Galvanic Isolator on your cable line which which is a surge protector of sorts which blocks DC currents, hum, isolates different electrical sections like between buildings which can cause very significant voltage differences, etc. The isolator should be installed somewhere after it enters your residence....mine was located right after the cable comes through the wall on its way to the cable modem.

If you do have an isolator it;s probably a case of the cable system not being grounded at enough locations, improper grounding, etc. And sometimes even with all the proper equipment installed, surge protection, and great grounding, a lightning strike can still get through to your equipment. And the path the lightning surge is talking is could really be through your electrical circuit back to your cable internet/TV line but it's just your cable modem is less resistant to surges than your other electronic equipment.

My cable has a GIS103D galvanic isolator installed...see this Link.

Knock on wood but I've been with True cable since mid 2011, went through some hellish lightning storms here in Bangkok, an so far my True cable TV and internet equipment has not suffered any damage from lightning. In fact had a mini lightning storm within the hour...only last about 10 minutes here in western Bangkok.

Below is a short youtube video giving an example of an galvanic isolator on a cable line....you isolator should look the same although with different manufacturer labeling.

Since your cable modem/router is actually on loan to you from True, they will replace it free of charge.

[Crossy]

You could ask about fibre to your desk (FTTX).

We have TOT fibre, works well and since the fibre is non-metallic is totally immune to lightning surges

Any surges on the mains will have a job getting to the router, we have multiple MOV devices and a dedicated AVR and UPS for the network.

[BuaBS]

When there is lightning near , unplug everything ! If you go out and there is a chance of lightning : unplug !

[Pib]

When there is lightning near , unplug everything ! If you go out and there is a chance of lightning : unplug !

Maybe not practical for all depending on the size of the residence and how easy (or hard) it is to disconnect everything...plus unplugging a cable modem from possible paths of surge requires disconnecting electrical power and also unscrewing the RF cable hooked to it's signal input....and of course the modem might be in a not so easy place to reach...I seen some homes where they have mounted them up on the wall close to the ceiling at the customer's request.

[thailanddogerator]

But most of the time fiber arrives in condo by building copper telephone cable, so is it really safe ?

You could ask about fibre to your desk (FTTX).

We have TOT fibre, works well and since the fibre is non-metallic is totally immune to lightning surges

Any surges on the mains will have a job getting to the router, we have multiple MOV devices and a dedicated AVR and UPS for the network.

[Crossy]

But most of the time fiber arrives in condo by building copper telephone cable, so is it really safe ?

That's why I stated fibre to the desk.

[recom273]

Make sure True installed a Galvanic Isolator on your cable line which which is a surge protector of sorts which blocks DC currents, hum, isolates different electrical sections like between buildings which can cause very significant voltage differences, etc. The isolator should be installed somewhere after it enters your residence....mine was located right after the cable comes through the wall on its way to the cable modem.

Do they all have isolators ?

I can't work out how to forward the ports on the slow Chinese hunk supplied by 3BB so, I have my own modem. Which blew up after a lightning strike.

I don't think I have an isolator, I have a modern house with an installed conduit for incoming internet cable and telephone sockets in the walls and I'm sure they just twisted the wires at the DP.

[Pib]

Make sure True installed a Galvanic Isolator on your cable line which which is a surge protector of sorts which blocks DC currents, hum, isolates different electrical sections like between buildings which can cause very significant voltage differences, etc. The isolator should be installed somewhere after it enters your residence....mine was located right after the cable comes through the wall on its way to the cable modem.

Do they all have isolators ?

I can't work out how to forward the ports on the slow Chinese hunk supplied by 3BB so, I have my own modem. Which blew up after a lightning strike.

I don't think I have an isolator, I have a modern house with an installed conduit for incoming internet cable and telephone sockets in the walls and I'm sure they just twisted the wires at the DP.

Cable (DOCSIS) is RF cable all the way to the cable modem just like Fiber to Home where the fiber runs all the way to the modem. There are no twisted copper phone/DSL wires involved. If you have a DSL/phone line going to the input of your modem you really have xDSL, not Cable or Fiber.

But the ISP providers confuse people in their advertisements where they sometimes include the word Fiber somewhere in their ad and it's actually may just be a hybrid system where Fiber feeds to a electronic junction box(es) in your immediate area/moobaan and from that junction box copper phone/DSL wire runs to the residence (that's what TOT has done in my moobaan). When the dust settles that is still just a xDSL system although it has a Fiber trunk line....so, the advertisement can't be said to be untrue since a Fiber trunk line was involved. Yes sir, the ISPs like to put the buzz word Fiber into the ads whenever possible, whether totally true or not.

[Berty100]

You could ask about fibre to your desk (FTTX).

We have TOT fibre, works well and since the fibre is non-metallic is totally immune to lightning surges

Any surges on the mains will have a job getting to the router, we have multiple MOV devices and a dedicated AVR and UPS for the network.

My cost is now 650 Bht/month. If I wanted fiber it would be 2500 Baht and about 30.000 Baht to pull the fiber from the exchange to my house.I think they still would do the last few meter in coaxial anyway.

Decisions decisions

[Berty100]

Make sure True installed a Galvanic Isolator on your cable line which which is a surge protector of sorts which blocks DC currents, hum, isolates different electrical sections like between buildings which can cause very significant voltage differences, etc. The isolator should be installed somewhere after it enters your residence....mine was located right after the cable comes through the wall on its way to the cable modem.

If you do have an isolator it;s probably a case of the cable system not being grounded at enough locations, improper grounding, etc. And sometimes even with all the proper equipment installed, surge protection, and great grounding, a lightning strike can still get through to your equipment. And the path the lightning surge is talking is could really be through your electrical circuit back to your cable internet/TV line but it's just your cable modem is less resistant to surges than your other electronic equipment.

My cable has a GIS103D galvanic isolator installed...see this Link.

Knock on wood but I've been with True cable since mid 2011, went through some hellish lightning storms here in Bangkok, an so far my True cable TV and internet equipment has not suffered any damage from lightning. In fact had a mini lightning storm within the hour...only last about 10 minutes here in western Bangkok.

Below is a short youtube video giving an example of an galvanic isolator on a cable line....you isolator should look the same although with different manufacturer labeling.

Since your cable modem/router is actually on loan to you from True, they will replace it free of charge.

I'm not on True but a local cable company, which leases the lines from CAT, and there is no galvanic isolator anywhere.I will talk with the cable company about this.

Is sucha galvanic isolator the same as Ubonjoe suggested, and can it be purchased locally at an affordable price?

My router and modem are also not on loan. With a 1 year contract paid upfront they wave the fee i normally have to pay to purchase the modem and router, but I think they replaced the router free of charge under warranty.

I also don't worry so much about that router, but there are many devices connected to my home network, and I think so far I was lucky that only the router ports and a cheap d-link switch were the only victims.

[gandalf12]

Surge protectors work fine but they have to be properly earthed in order to do so

[SoiBiker]

Surge protectors work fine but they have to be properly earthed in order to do so

Not necessarily. Some have the MOV connected to neutral instead.

[Pib]

A galvanic protector and surge protector are different although the basically look the same physically. A surge protector is purely to limited big surges on your cable/satellite line (like lightning) where a galvanic protector deals with the stuff I mentioned earlier.

[Berty100]

Surge protectors work fine but they have to be properly earthed in order to do so

Not necessarily. Some have the MOV connected to neutral instead.

Whit neutral do you mean the harness of the coaxial cable?

[Pib]

Surge protectors work fine but they have to be properly earthed in order to do so

Not necessarily. Some have the MOV connected to neutral instead.

Don't get a surge protector meant for electrical lines and cable/satellite lines mixed up...they are different animals.

For a power line surge protector the best surge protectors have MOV across the line to neutral, line to ground, and neutral to ground since surges can occur in three different modes (L-N, L-G, & N-G).

[SoiBiker]

Some of them do both.

[Beats56]

There are surge protectors available with cable coax connectors - I know Belkin make one. Maybe that would help?

[Beats56]

Surge protection will not help with a lighting strike...too much voltage. I know because I lost a satellite reciver and a audio video reciver when my dish got hit in Canada. Was told they are useless with lighting. Best to just unplug electronics when a electrical storm is in the area.

[Berty100]

Surge protection will not help with a lighting strike...too much voltage. I know because I lost a satellite reciver and a audio video reciver when my dish got hit in Canada. Was told they are useless with lighting. Best to just unplug electronics when a electrical storm is in the area.

That could maybe an option when you're at home, but it was a short storm anyway so you may not expect this to happen, but nobody unplugs his cable modem each and everytime he goes out.

[Beats56]

Ya i know but when it happened to me I just finished a night shift and the wife was watching TV and I was in bed. Then a great big Kaboom made me jump out of bed. In fact a tree got zapped too down to the roots. I know you can't be home all the time but when you are just isolate the gear when a storm is in the area just to be safe

[sandrabbit]

Beats56, on 14 Nov 2015 - 21:07, said:

Surge protection will not help with a lighting strike...too much voltage. I know because I lost a satellite reciver and a audio video reciver when my dish got hit in Canada. Was told they are useless with lighting. Best to just unplug electronics when a electrical storm is in the area.

you are correct, a direct lightning strike can put thousands of amps through your equipment or at least try to till it basically evaporates breaking the electrical connection. all this talk of galvanic isolation, ie a transformer, will not work because the high voltages involved with a direct lightning strike will just break down any insulation involved. the clock displays on my microwave and oven are damaged due to spikes on the line which these devices will prevent, I think I'm going to install a few constant voltage transformers and for the more delicate equipment ups's. you can't protect 100% against direct lightning strikes as the supply cables are hanging in mid air, if you have devices like ups's then maybe they will die to protect your equipment but unlikely, I'm from heavy steel industry industrial electronics and the joke is that the equipment dies to protect your fuses ............

[SoiBiker]

I find that living in a low rise surrounded by tall buildings is the best protection.

[sandrabbit]

SoiBiker, on 14 Nov 2015 - 21:45, said:

I find that living in a low rise surrounded by tall buildings is the best protection.

you need to see some documentaries on lightning, it does some very strange things like going round in circles and even making 90deg direction changes.

[sandrabbit]

I've just remembered something, if any of you have sheds with a metallic roof (ie galve sheets) and the walls of the shed are insulators then it's not a safe place to be even without a direct lightning strike. I read about this in the 70's, if you are close to a thunderstorm the air gets charged and the shed acts like a capacitor and if discharges the charge will go through you to ground. I see so many Thai homes with tin sheet roofs and it makes me nervous.

Edited November 14, 2015 by sandrabbit

[Berty100]

I start thinking that the strike must have been a distance away, because if thousands of Amp would go through the equipment, I assume i would have much more damages.

So could it be that the strike was actually quite a distance away, and passed through several junction boxes etc before it reached my place, and had already lost most of it's power?

[Bench499d]

Cable (DOCSIS) is RF cable all the way to the cable modem just like Fiber to Home where the fiber runs all the way to the modem. There are no twisted copper phone/DSL wires involved. If you have a DSL/phone line going to the input of your modem you really have xDSL, not Cable or Fiber.

But the ISP providers confuse people in their advertisements where they sometimes include the word Fiber somewhere in their ad and it's actually may just be a hybrid system where Fiber feeds to a electronic junction box(es) in your immediate area/moobaan and from that junction box copper phone/DSL wire runs to the residence (that's what TOT has done in my moobaan). When the dust settles that is still just a xDSL system although it has a Fiber trunk line....so, the advertisement can't be said to be untrue since a Fiber trunk line was involved. Yes sir, the ISPs like to put the buzz word Fiber into the ads whenever possible, whether totally true or not.

Not sure this is correct. I have had DOCSIS cable both here and in the UK and both installations have been of the FTTC (fibre to the cabinet) type, where the last few tens of metres is delivered over copper. Here in Bangkok we have a copper coaxial cable (same as you get to the TV box) running from a port on one of the poles outside into our premises. I don't think that's where the fibre terminates either, probably on the main road at the bottom of the soi, so copper for a couple of hundred metres. True.