Fiber Optic Cable Lighting Strike??

On Wednesday it was said to me by a customer that a lightning bolt hit the fiber cable to their house and blew the Fiber box off the wall. Verizon had to replace the whole box.

It was stated to the customer by (I assume) the Verizon guy, that the lightning strike that hit a tree and blew out the ground from the tree in a line to across the driveway (some 30 feet long)to a point where the fiber is buried. This point is easily 1/4 mile from the house and followed it to the Fiber/Phone box blowing it off the wall and knocking out the phone service.

I had to replace the phone line protector that I had installed on the security panel. Panel was ok and functions with out a problem.

There a lot of "Say What's???" and "Really's??" in the story above.

The fiber runs on top of the underground power cables that run beside the driveway.

So what is your opinion??? :-)

Later,

Les

Reply to
ABLE_1
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If the fiber had a metal sheath (mine does), it could certainly have carried the surge to the home. Lightning blowing a box off the wall is nothing unusual. I've seen a well controller blown off the wall when lightning hit the customer's well. That particular strike also blew out the alarm panel, a TV set, etc. The panel was grounded to the same point as the other services but the well acted as a separate ground, creating a potential between it and the building's electrical ground rod. This happened quite a few years ago, actually before I learned about the importance of bonded grounds. Years later, when an electrician friend explained the concept to me, I remembered this event and realized it might have been avoidable.

Reply to
Robert L Bass

that's impossible. one of the reasons to go with fiber is it's immune to lightening.

Reply to
Bob

The fiber itself is... a metal-sheathed fiber cable isn't.

Reply to
Matt Ion

I haven't used fiber but that seems stupid to make it suseptible to lightening like that.

Reply to
Bob

It would be stupid to bury something that (relatively) delicate without some sort of physical protection.

Reply to
Matt Ion

makes it easier to find later on by the installing co if they need to service it or mark the path for future digging.. RTS

Reply to
RockyTSquirrel

that makes some sense. I fail to see how a little metal foil or whatever is in there is going to protect it from a back hoe. Still makes little sense to me to have a medium that is lightening proof and then add metal to it to defeat that.

Reply to
Bob

the difference between designers (i.e. engineers) and real world applications RTS

Reply to
RockyTSquirrel

The medium remains lightning proof. Nothing passes through the fiber and into the connected hardware. The sheath is typically grounded at one end but not connected to the equipment itself.

Reply to
Robert L Bass

Lightening proof? the OP said it blew the NIC off the wall and fried his protector on the alarm panel. I wonder if the fiber was damaged? Need new ends? What else damaged?

Reply to
Bob

It was just the IMAGE of the lightning traveling through the fiber...picture that.

Reply to
Crash Gordon

That's the thing: none of it is 100% protection, but you have to protect what you can, where you can. A thin metal sheath (not necessarily foil) won't protect it from a backhoe - heck, some folks up here found even oil pipelines aren't safe from a misguided backhoe - but it will protect it from a lot of smaller physical shocks, such as shifting ground caused by vibrations of daily traffic, and so forth.

And yeah, the lightning doesn't damage the fiber itself, but as the story shows, it can cause damage to the surrounding cable or other attached devices, the result of which COULD damage the fiber itself.

Ultimately I think the very rare possibility of this sort of lightning damage is far outweighed by the protection of a strong metal sheath against other sorts of daily stresses.

Reply to
Matt Ion

The medium is the fiber and the data being carried on it. That is indeed lightning proof.

That's because the metal sheath carried the current. Absent that sheath, fiber itself is not affected by electrostatic activity.

Presumably anything connected to the NIC with a conductive cable or other path.

It also helps (somewhat) with rodents and stuff.

Apparently so, since so much outside plant FO cable is similarly protected.

Reply to
Robert L Bass

No defined is where lightning currents flowed. For example, did surge current enter on AC mains and seek earth ground by arcing to the cable sheath? Was the Verizon box earth ground same as AC electric ground (yes, even the Verizon box is typically earthed). The NID exploded because current passed through it. To better understand why damage occurred, first, the electrical path that passed through a Verizon NID must be defined.

If the current arced inside the NID, then that could account for an explosion. So why was current passing through that NID? It implies the NID and AC electric had separated earthing connection. Meanwhile, insufficient information (ie how AC electric was routed and earthed) was not included. Only known fact is that massive current (for some reason) passed through the NID.

Reply to
w_tom

None of us are safe from a misguided blackhoe when laying pipe.

Reply to
G. Morgan

You guys don't have free blue-stake services where you're at?

Reply to
Crash Gordon

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