Lightning Protection For Phone Line

[canopy]

I've lost several routers and a motherboard due to lightning strikes through the phone line. Lightning also made the phone line protection built on my UPS inoperable. I've noticed the phone line does not appear to have any sort of protection--it is strung across the street and goes straight to my router. Are there some ways to improve lightning protection?

[mogandave]

Install a rod?

[Crossy]

Plenty of phone line surge arrestors about, Pantip, Fortune or Zeer should be your first port of call. Ensure you get one with an earth connection and connect it to earth.

Alternatively a good quality surge arresting traily lead (Belkin are excellent) will provide both mains and phone line protection in one unit.

[terryq]

A small surge suppressor box is usually fitted to a phone line at point of entry, this has an earth terminal and should be connected to earth. I believe it contains a couple of varistors (may be wrong). As Crossy says adding your own is worth doing anyway. Should protect from induced voltages due to lightning strikes nearby.

But if a direct strike to the phone line or electric supply could lose a lot of equipment even if switched off. ( speaking from experience) For severe local electrical storms always suggest unplugging equipment.

[Daffy D]

Lightning also made the phone line protection built on my UPS inoperable.

This happened to me some time go.

I removed the little phone line protection unit from the UPS and got it fixed by one of those repair places at the back of Pan Thip.

A couple of replaced transistors and it worked again.

:-)

[Pib]

I can associate with the OP. Last year lightning hit my next door neighbor's house...literally blew a hole in the top of his concrete fiber roof...punched a hole about the size of a dinner plate....and I'm here to tell you that when that lightning strike hit at around midnight during a bad, bad thunderstorm the thunder just about made my heart stop as the flash and thunder (LOUD) occurred at the same time which means that lightning strike occurred very, very, very close to me. I thought it had hit my house...and maybe it did...but next morning I saw it had definitely hit my neighbor's house...only a few meters separate our houses.

And during that same millisecond, my TOT modem which was hooked to my Linksys Wifi Router which was hooked to my VOIP adpater/box which was hooked to a cordless phone were damaged/smoked (smoked meaing didn't work anymore)...either their power adapters were smoked or the devices themselves smoked. I also had another cordless phone hooked directly to the phone line downstairs that got smoked. The only electronic devices damaged in my house was those which had a direct or indirect connection to the phone/ADSL line. All my other electronic devices (e.g., TVs, TV settop boxes, A/Cs, microwave, etc...etc...etc) hooked to the AC outlets were not damaged; only devices that were directly/indirectly hooked to the phone/ADSL line. Yes, sir, lightning had found a path through my phone/ADSL lines.

A common surge arrestor/protector can work if the voltage surge/spike comes in on only 1 of the 2 wires/lines making up a phone line. But with lightning strikes the voltage surge can easily ride in on both wires making up the phone line which will render a typical surge arrestor/protector connected across the wires useless since both lines are at the same voltage potential which prevents the MOV from diverting the voltage potential...a voltage potential which could be thousands (or hundreds of thousands or millions of volts for a few milliseconds) from a nearby lightning strike...the high voltage spike continues to the device/modem/router without being reduced in size/diverted to ground. Same goes when lightning rides in on a 220V/110V electrical hookup.

These low cot arrestors/protectors you buy, like a power strip that says it comes with surge protection, are usually no more than a 5 baht MOV (Metal Oide Varistor) connected across the two wires...the wires that normally has voltage potential/carrying the signal and the neutral wire....then the MOV briefly diverts/partially shorts when the voltage on one line exceeds a certain voltage value. For phone line arrestors it's pretty much the same setup with a 200V AC MOV across the two wires with maybe a torrid coil thrown in based on my research and from opening up a cheaper phone line arrestor I bought. As FYI, MOVs used in power strips normally have a 500-700V AC varistor voltages.

Anyway, unless you have a protector set-up which can divert voltage spikes to a nearby ground, like your home's Earth/Safety ground if you home has 3 wire electrical wiring, and the voltage arrestor/protector uses three MOVs in the three modes to divert voltage spikes coming in on either the two phone wires the phone surge protector may not do you much good. The three modes a voltage spike can ride in on is: 1): Line/Signal wire, 2) Neutral/Low wire, and/or 3) Line/Signal & Neutral/Low wire at the same time. And in order to protect form these three modes/ways a voltage spike can ride in is to have a MOV connected across the line normally carrying the potential/signal to the neutral wire, a MOV from the potential/signal carrying wire to Earth ground, and one MOV across the Neutral an Earth ground wires. This three mode setup will divert a voltage spike to a lower potential regardless of which wire(s) the voltage spike tried to sneak in on.

I know, too complicated talk for some, but I just wanted to point out that if you have a phone or AC line surge protector which only has surge protection across the Line/Signal-to-Neutral/Low lines you only have some protection in one mode that the voltage spike can occur compared to the three modes where protection is needed. Buy hey, having protection on one mode is better than nothing....that what I currently have setup via a 50 baht phone line surge protector...but on my AC power which my electronic devices are hooked into I have the modified them to have 3 MOV. Note: I bought a couple of low cost "surge protected" power strips, opened each one to do my modification, and each one only had the 1 MOV across the Line-to-Neutral wires. Yes, I know I could install one of those whole house main circuit box protectors or a bunch of UPS's but those can be pricey for a retrofit....I'll just just my modified/improved power strips and unplug my landlines during thunder stroms....my internet is now via True cable interent which means I've just provided another way for lightning to get into house, but at least True did install a lightning arrestor in the cable line (of course it's only a single mode protector).

Best thing to do during a thunder storm is unplug every thing you can and hide under the bed until the storm is over.