Is there always some sign of damage when lightning strikes

[rob569]

Possible lightning strike seems to knockout phone system in a small office, but nothing else. No wire damage of any kind anywhere. It is a small older switch that handles 2 lines.
Right now only the phone switch is down and not the the satellite modem for the internet, wireless router, or the wired router. All are plugged into a surge protector. Only the phone switch isn't working, but shows no physical sign of damage. The phone tech says the lightning from the storm we had late Thursday night and early Friday morning knocked it out. I don't think so. This phone system seems to go in and out all the time. What do you guys think, a lightning strike so precise that it only effected one lone piece of equipment and nothing else, just doesn't seem likely. I know anything is possible, but come on! Someone give me a little education on lightning issues with phones systems.

 

[hurk27]

Possible lightning strike seems to knockout phone system in a small office, but nothing else. No wire damage of any kind anywhere. It is a small older switch that handles 2 lines.
Right now only the phone switch is down and not the the satellite modem for the internet, wireless router, or the wired router. All are plugged into a surge protector. Only the phone switch isn't working, but shows no physical sign of damage. The phone tech says the lightning from the storm we had late Thursday night and early Friday morning knocked it out. I don't think so. This phone system seems to go in and out all the time. What do you guys think, a lightning strike so precise that it only effected one lone piece of equipment and nothing else, just doesn't seem likely. I know anything is possible, but come on! Someone give me a little education on lightning issues with phones systems.

There is no easy answer to lightning, it is a subject all of it's own, and there are many myths out there that confuse it even more.

First lightning is a high frequency/high energy event, this means it can do damage without even making contact with the equipment it can damage, it can induce a high voltage on conductors in a building without even hitting the building, and in fact is the most common type of damage cause by lightning, what lightning hits is more a function of the frequency at the time of strike rather then the grounding, if we can understand how radio waves work, and how the build up of electrons on a receiving antenna occur when the antenna is the right wave length for a particular frequency we will start to understand how and why lightning can hit a tree right next to a very well grounded and much taller radio tower, and never touch the tower, so in essences of your question:

Yes lightning can damage a single telephone without any out right visual damage, and yes it can do this without damaging anything else, it all depends upon the frequency of the lighting at the time of the strike and the impedance of the pathways it might or might not take.

Here is a post I made to a similar question in another thread:

Lightning is a very high frequency event, and does not always follow the the path that would be a low impedance path @ 60 Hz. with a mean center frequency of around 10 MHz, but can go as low as 20 kHz to as high as 100 MHz, we can see these paths can look as an open circuit to lightning, this is one of the reasons we see some weird things that lightning may strike even when a path to earth we think is good is right next to the point of attachment, and can even be connected to it, I have had this happen, lightning struck a telephone demark, bonded to a well grounded meter can less then 6" away, but the lightning current followed the 22 awg wire around the building for 60' and jumped to a chain link fence, in another case which I used to have photos of, was a 300' tower with all kinds of grounding electrodes, was missed by less then 15' to a 15' high tree, well the tree made a good broad band antenna. trees are struck more then any other structure in the world, and that is a fact.

 

[hillbilly1]

Sometimes lightning makes small holes in the insulation too small for the eye to easily see, just pulled out a parking lot feed that megged bad, but the only evidence of a bad wire was the equipment ground was no longer green, but black for about 100'. Could not see any damage on the phase conductors, but it was there just the same.

 

[cadpoint]

Co-worker described a lighting stike on a tower today, a Cell Tower with flashing light!

Direct hit for oh a second or longer or as preception will have it... a really continual/melting hit! That for a finally leaped back up of the tower to the sky and the airial flashing light was still flashing.

The lighting bolt will do about what it wants but one has to remember that other structures and objects see some of this power when it lands on earth.

I'd check the D-mark, and make and assure the wires are fast!

Other than assuring that the old lines are good and ring out I don't know what to say about their switcher and the phone guys novice statement.

 

[K8MHZ]

Sometimes lightning makes small holes in the insulation too small for the eye to easily see, just pulled out a parking lot feed that megged bad, but the only evidence of a bad wire was the equipment ground was no longer green, but black for about 100'. Could not see any damage on the phase conductors, but it was there just the same.

We see coax with pinholes through the outer insulation from lighting strikes on occasion.

A friend has a piece of glass that a bolt of lightning melted a hole through.

 

[brian john]

Possible lightning strike seems to knockout phone system in a small office, but nothing else. No wire damage of any kind anywhere.

Seems you have signs of damage!

 

[petersonra]

I had a control panel once that was fed out of a power panel coming from an MCC that got hit by lightening. The MCC was a total mess and was not even repairable.

The service engineer said the wire going from control power transformer in the MCC to my control panel was black.

Oddly, it destroyed a circuit breaker and a couple of MOVs in the control panel, (melted them) but did no other damage in the control panel, despite a lot of low voltage stuff it could have whacked.

It may have been a sign of things to come though. It was some kind of oil recovery project that did not work real well so when the company closed it down the bulldozed the control room, MCC, equipment, and control panel into a nearby gully and covered it with dirt.

 

[Drake5265]

This is a perfect example of why people should buy lightning arrestors and whole house surge arrestors. Onje time I had a controller litterally blow off of a furnace from a lightning strike. Two nights ago we had Tornado's in my state and tons of lightning and wind in areas that I used to service when I was in business for myself yesterday I sent out a bunch of my pals who were all out of work journeymen to install you guessed it lightning and surge arrestors and reattaching service risers as well.