Prevent lIghtning damage on phone system?

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2010 10 24

I’m the technical support person for a small rural campground, and my wife and I live here. We have an electronic telephone system with voice mail, forwarding, etc. on a dozen extensions, both digital and analog, scattered around 300 acres and up to half a mile away from the main office. My wife and I came home from a movie last night and all of the electronic telephones were dead after (apparently) a lightning storm. BUT the two DSL modems, routers, and computer systems were OK (I’m using it right now), AND all the mechanical, analog phones worked OK. Short term solution is to replace the electronic telephones. But what’s the best long term solution? This is not the first time something like this has happened. Options include:
1. install lightning arresters on all extensions and incoming telephone land lines – but I’ve heard that these things are not very reliable and hard to test,
2. Try to migrate the telephone system to some internet based system, but I don’t know how to do that, and this makes the telephone system dependant on the incoming DSL line, which also is not all that reliable,
3. Try to migrate the telephone system to cell phones, but cell phone service is also not very reliable and I don’t know how you have a cell phone system with a dozen extensions.
Does anybody have any advice, recommendations, or suggestions? Thanks in advance for any comments.

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You might consider installing Telephone surge supressors.

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You’re not going to like this answer, but short of unplugging everything (phone cords and electrical power supplies) when a storm approaches there’s not much you can do other than your #1 suggestion and Clint’s suggestion.

I’m a retired telephone service tech and through the years I’ve seen it all. Back in the “good ole days” (when a phone was just a phone) it could take a lightning shot. The bell would jingle a couple of times and no harm done. However, with modern circuitry, all it takes is static electricity to knock out a phone. There is no way surge suppressors can protect you from a direct hit or even a close hit.

You didn’t mention how the extensions are connected to the system. If using aerial or buried plant, a lightning shot anywhere near the wires can lead to damage. The wire is usually a better ground than trees or other objects and lightning heads for the best ground.

Today most phone circuits use “gas arrestors” for lightning protection. These arrestors supposedly direct the excess voltage to ground and then reset themselves. In the old days “carbon arrestors” were used to provide the same protection. However, they would not reset and would have to be replaced after a lightning shot. In addition to the arrestors the really old telephone protectors had a fuseable link. Nothing more than a really light gauge wire in series with the circuit. Similar to the old automotive glass type fuses.

You can try the following to increase your odds during a lightning strike:

1. Use approved telephone protectors on each extension where it leaves the switch and at the termination point.
2. Make sure each protector is grounded or bonded to the electrical system ground. (must have zero ohms resistance between electrical ground and protector ground)
3. Install a fuseable link at each end of the circuit. Be sure to fuse both sides of the cable pair.
4. Install lightning rods on the buildings involved.
5. Unplug everything.

JB

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Thanks for responses above. What about fiber optic or infrared devices that provide a non-electrical gap in the line? I don’t know if such devices are available or cheap, and I don’t know what to call them if they are available, but it seems possible and foolproof since there would be no electrical connections between the two sides. Has anybody ever heard of such things?

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This reminds me just how inadequate we are when it comes to “Acts of God”.

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Fibre still relies on electrical systems at the ends and they are really for fast data, not voice, so the price is reflective of the use.
Good old copper pairs and some gas arrestors are your best bet.

cheers, Paul

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