Question on Lightning Protection for Networks

[raleighthings]

Helpful post. Thanks!
Did you come by all this knowledge the hard way?

I have a few scars if that's what you mean.

Electrical engineering in school many decades ago. Then computer development, hardware and software, for 2 decades. Then computer admin for a long while.

 

[thiggins]

Thanks again for the post. Folks like you are the reason why people come to the SmallNetBuilder Forums!

 

[timby]

<Warning. Long boring post on surge.>
<Also, I'm open to correction.>

Having devices on surge protectors all over a house doesn't help much in a lighting strike. Or even a near miss. Say anything within 1/2 mile or less.

<snip>

Thanks for the input. With most households getting more and more high-tech gear in their homes it stands to reason that there should be better ways to protect their investments that what's currently available.

It seems when I think I have one thing covered another crops up. Since i don't have deep pockets, I try to protect my investments the best I can with what is being touted as the leading technology for spike suppression. I consulted several folks in the business for what is needed. I was told a good UPS (APC) would be the best. So I purchased these for my home systems. They work fine for the PC but who would think that a near strike would get past the grounding already in the system. The ONT from Verizon has a wire going to a rod that was driven at least 3 ft into the ground. Obviously that wasn't enough as it fried the power supply for the ONT.

I now have my CAT5 running through a surge protector but am not sure that will be enough. I guess I'll keep a bunch of NIC cards around for the next hit....

 

[raleighthings]

They work fine for the PC but who would think that a near strike would get past the grounding already in the system. The ONT from Verizon has a wire going to a rod that was driven at least 3 ft into the ground. Obviously that wasn't enough as it fried the power supply for the ONT.

I now have my CAT5 running through a surge protector but am not sure that will be enough. I guess I'll keep a bunch of NIC cards around for the next hit....

Lightning nearby will come into your house. See my large wave analogy above. It will come in through every conductor. Even semi-moist dust on a wire jacket. So to ride this wave you want everything to a common ground stake so it rides up and down the voltage potential in unison. Which is why every service into your house should be tied to a common ground. Which works better if every service enters at the same point of your house.

As to the 3' ground stake, it's been a while since I actually put one in (40 years) but I think most codes require 8' to 10' or more. You want to get well below the frost line down to where the dirt stays moist 99.999% of the time. And no, I have no idea what they do in Vegas.

I had a client who didn't see the point about 15 years ago to upgrade the grounding in the building. After all his key system phones had never had any issues. After the 3rd time we blew out $4000 worth of phone and computer gear he got serious. We put in a new ground stake for the power and ran nice copper from that to each location where we had racks and where the phones and cable came in. No issues since and that was about 6 or 7 years ago.

We also found out that the ground for the phones up to that point was to a water supply line that went under the concrete at the front of the building and out under the sidewalk. But the line was disconnected inside the building. And outside there were no meters nearby. Owner said oh, yeah, they redid the water 20 years ago when the dug up the street and reworked the sidewalks. So this ground likely went down about 2' then out a foot or two and was cut off.

 

[thiggins]

We also found out that the ground for the phones up to that point was to a water supply line that went under the concrete at the front of the building and out under the sidewalk. But the line was disconnected inside the building. And outside there were no meters nearby. Owner said oh, yeah, they redid the water 20 years ago when the dug up the street and reworked the sidewalks. So this ground likely went down about 2' then out a foot or two and was cut off.

Great story. The moral is: know where your grounds go!

 

[timby]

Lightning nearby will come into your house. See my large wave analogy above. It will come in through every conductor. Even semi-moist dust on a wire jacket. So to ride this wave you want everything to a common ground stake so it rides up and down the voltage potential in unison. Which is why every service into your house should be tied to a common ground. Which works better if every service enters at the same point of your house.

As to the 3' ground stake, it's been a while since I actually put one in (40 years) but I think most codes require 8' to 10' or more. You want to get well below the frost line down to where the dirt stays moist 99.999% of the time. And no, I have no idea what they do in Vegas.

I had a client who didn't see the point about 15 years ago to upgrade the grounding in the building. After all his key system phones had never had any issues. After the 3rd time we blew out $4000 worth of phone and computer gear he got serious. We put in a new ground stake for the power and ran nice copper from that to each location where we had racks and where the phones and cable came in. No issues since and that was about 6 or 7 years ago.

We also found out that the ground for the phones up to that point was to a water supply line that went under the concrete at the front of the building and out under the sidewalk. But the line was disconnected inside the building. And outside there were no meters nearby. Owner said oh, yeah, they redid the water 20 years ago when the dug up the street and reworked the sidewalks. So this ground likely went down about 2' then out a foot or two and was cut off.

Thanks again for the enlightening commentary on grounding and lightning.

I'm not sure about my electrical (grounding requirements) as the regulations here in Texas seem to be sketchy, at best, especially concerning homes built over 30 years ago.

I do know that when Verizon installed the FIOS ONT their requirements were for a copper rod to be installed at least 3 ft into the ground with the recommended grounding wire attached from the ONT.

The wire is intact and I didn't lose any electrical devices in the house. The power didn't go out. The strike seems to have entered through the CAT5 that runs around the exterior of the home. I'm hoping the measures I've taken will mitigate any new incursions but don't have a warm-n-fuzzy.

Again, thanks for your insights ....

 

[Tinger17]

Would this work??

Thanks again for the enlightening commentary on grounding and lightning.

I'm not sure about my electrical (grounding requirements) as the regulations here in Texas seem to be sketchy, at best, especially concerning homes built over 30 years ago.

I do know that when Verizon installed the FIOS ONT their requirements were for a copper rod to be installed at least 3 ft into the ground with the recommended grounding wire attached from the ONT.

The wire is intact and I didn't lose any electrical devices in the house. The power didn't go out. The strike seems to have entered through the CAT5 that runs around the exterior of the home. I'm hoping the measures I've taken will mitigate any new incursions but don't have a warm-n-fuzzy.

Again, thanks for your insights ....

Sorry to revive this post, but I had EXACTLY this happen to me this week. FIOS ONT was FRIED. Verizon replaced that as well as the modem. I lost several NIC's in the process, unfortunately, one also took out a motherboard.

My network: FIOS ONT - coax - Actiontek router (4 port hub) - pulled cat5 - multiple computers. Each of them has a UPS (without Cat5 protection).

Thinking about this, I had an idea, and wanted your thoughts on how to prevent this from happening again.

1) If I took a wireless 4-port router and configured it into an access point (which I did to repeat the wireless signal upstairs), and then plugged all the cat 5 into that, then I would be isolating the wired network from the computers all at once. Only downside might be performance. Only 2-3 computers on at any one time, so would this be worth considering? Or would this simply be like giving up the speed of the FIOS network smushed down into the 54mb wireless transmission? Seems like this might be cheaper than putting surge on each of the cat 5 connections?

OR

2) can I put a COAX surge protector in-between the ONT and the actiontek router to stop surges after the ONT and before any of my network cabling and still expect good service from the Actiontek?

Thanks!

 

[thiggins]

1) If I took a wireless 4-port router and configured it into an access point (which I did to repeat the wireless signal upstairs), and then plugged all the cat 5 into that, then I would be isolating the wired network from the computers all at once. Only downside might be performance. Only 2-3 computers on at any one time, so would this be worth considering? Or would this simply be like giving up the speed of the FIOS network smushed down into the 54mb wireless transmission? Seems like this might be cheaper than putting surge on each of the cat 5 connections?

OR

2) can I put a COAX surge protector in-between the ONT and the actiontek router to stop surges after the ONT and before any of my network cabling and still expect good service from the Actiontek?

Neither is going to help if you have a close enough strike and big enough surge.
The grounding solution mentioned previously is your best protection

 

[westom]

The wire is intact and I didn't lose any electrical devices in the house. The power didn't go out. The strike seems to have entered through the CAT5 that runs around the exterior of the home. I'm hoping the measures I've taken will mitigate any new incursions

To know that means tracing the complete path from cloud to earth. What did it go through? Not everything that conducted that current will show damage. Usually damaged is only one item in a long list of conductors between cloud and earth.

Most common entry point is via AC mains. Many assume this is a nearby strike. But a strike to AC mains down the street is a direct lightning strike to your household appliances. However, not all appliances make the better connection to earth. And a direct strike to AC mains does not mean power interruption.

For example, incoming on AC mains. Shunted from black (hot) wire to white (neutral) and green (safety ground) wire by a plug-in protector. Now that current has a path around that computer's power supply and directly into motherboard and network interface. Down network to what that eventually connects to earth? Appreciate the motherboard could conduct that surge and not be damaged. Quite normal is for most items to conduct a surge without damage. You must connect the dots between damaged items.

A three foot ground rod is insufficient. Every incoming wire must connect short (ie less than 10 feet) to the same earthing electrode. Connected directly (ie coax cable) or via a protector (that old telephone wire, AC electric). Others have made the same point.

Also critical is how that earthing is connected. Previously noted is the 'less than 10 foot' requirement. Also no sharp bends. No splices. Ground wire not inside metallic conduit. Ground wires well separated from other wires. All this says why safety grounds (to wall receptacles) are not earth grounds.

Needed on any home that has transistors is one 'whole house' protectors in the breaker box. Then breaker box ground must also meet those earthing requirements. For example, if the quarter inch bare copper wire goes up over the foundation and down to an earthing electrode, then it has compromised surge protection. Ground wire must go through foundation and down. Eliminate the sharp bends. Separate it from other wires. Make the connection shorter. All are important when grounding also for surge protection.

As others have noted, that energy must be dissipated in earth. Any surge current permitted inside the building means it will go hunting for earth destructively through electronics. Routine is to have direct lightning strikes without damage even to any protector. Routine is to have surges and never know that surge existed. Routine to having no damage is a protector properly earthed short to the single point earth ground, OR having that wire connected short to earth (no protector). Distance to single point earth ground and other requirements are important for protection.