Why Motorola R-56 exists.

[kayn1n32008]

This site took a direct lightning strike on Monday during a decent storm that rolled through


This 4” sq junction box had it’s cover blown off and was found about 30’ away

This is the Weather proof enclosure that the sites power comes into. As you can see the door was blown off

This is the remains of the DIN rail mounted 15A breaker in the enclosure.


This is all that remains of a single 115v/15A DIN rail outlet.


This is all that remains of the DLink surge ‘protected’ power bar plug. You can see the other end of the cable in the background although it’s blurry.


There was $15-$20k worth of damage to the site. All 3 microwave link radios were destroyed, at least 4 of 8 AP(4x AP per band) radios were destroyed along with all the power supplies and lightning arrestors inside the equipment cabinet. My wife watched the strike occur as she was driving into town, and our tenant living in our house damn near had to peel herself off the ceiling in side the house. My house Is about 60m away from the tower. The tower is just shy of 43m tall

 

[kayn1n32008]

Only casualty in the firehall appears to be the Telus satellite receiver. The dish is right near the equipment cabinets and the feed line to the receiver runs along the exterior wall past the tower. My best guess is the lightning strike induced a current onto the shield and it cooled the receiver.

 

[mmckenna]

This site took a direct lightning strike on Monday during a decent storm that rolled through

Wow, glad you guys are OK.

I think people underestimate what sort of damage lightning can do. I see to many hobbyists that ignore the basics. They assume their choices indicate wisdom rather than luck.

I was on a ship that took a lightning strike to the mast once. Didn't damage the radar, didn't damage any of the radios. Did blow out an engine management computer all the way down in main propulsion, below the water line.

Lightning doesn't play by our rules.

 

[PACNWDude]

Sadly, even in corporate settings, I have experienced cost cutting when it comes to adherence to R-56 and site installation of radio equipment. That changes immediately after a lightening strike. While working on ships, it was very common to have antennas hit in the Gulf of Mexico, and Polyphaser's, grounding of equipment and best practice's in R-56 saved the radio gear. Even retrofitting a building or office with ground buses and thick ground wire is better than nothing. The damage from fire, or electrocution is not worth the cost savings. Do the web search and download of copy. Know it, love it, live it.

 

[jim202]

Having worked in the cellular field for many years, we had very strict guidelines that we followed in lightning protection and site grounding.

My first thought is what kind of grounding was installed at the base of the tower? The next question is did each of the guy wires on the tower have grounding at the anchor points? Getting to the building, is there a ground ring in place around the building? Was there a master ground bar inside the building near the coax and power entry points? Were all the equipment racks inside the building tied into the master ground bar inside the building? Did each coax cable coming into the building have a ground both outside as they enter the building and a surge protector that was grounded the the master ground bar on the inside? Last question is did the power coming into the building have a master surge protector on It that was connected to the common ground system? Do the telephone lines coming into the building have surge protectors on them?

It is possible to survive a direct tower strike, but it does take a concerted effort. There are many on the chat groups that say there is no way you can survive a direct strike on your facility. If this was the case, all the radio and TV stations would be off the air all the time when a storms rolls through. All the cellular system towers would go off the air from a strike. This generally no longer happens due to careful planning of the grounding system for the facility.

Damage happens when there is current flow where it doesn't belong during a lightning strike. Be it between equipment racks, the coax arcing to an equipment rack or other control wires. The possibility goes on and on. The intent of grounding (bonding) everything together is to reduce or stop and current flow between different things in the equipment building. Even the metal conduits inside the building are bonded to the grounding system. If you ever get a chance to look inside a communications building, you will even see the metal grating and louver frames are grounded.

Grounding is not low cost. How much you put into it will determine what the damage will be. The owners of the radio equipment would rather spend money to keep their facilities up and running, rather than spend the money not making any income and also paying to repair or replace damaged equipment.

I have got long winded here, but you really need to step back and see the whole picture of what is involved with lightning strikes.

I was sitting in my van during a strong thunderstorm one day, waiting for the heavy rain to stop. Saw the tower take a strike and then the tower legs were steaming from the heat the lightning strike caused with the high current going through the tower legs to the grounding system. Until you see something like this first hand, you really can't get the true impact a direct strike on a comm tower.

Entering the equipment shelter after the rain stopped, I didn't really know what I would find. Everything was working just fine except one cabinet off by itself. It belonged to a local ham club. They were told several times to make sure they grounded their cabinet and put surge protection on the repeater. So now they need to figure out how to repair their radio package.

 

[03msc]

I think people underestimate what sort of damage lightning can do. I see to many hobbyists that ignore the basics. They assume their choices indicate wisdom rather than luck.

I would be curious, and I am being serious here, what you suggest as the basics that a hobbyist/ham should have for a VHF/UHF station? I have basic lighting arresters (which I know won't stop a direct hit...) that are grounded but I've also read people say that they are pointless since, as I said, they won't stop a direct hit. Obviously there are other reasons to have it but for those who stumble across this and wonder "well, what should I have...?"...what would you tell them?

 

[NVAGVUP]

R56 is the benchmark for good reason.

Many years ago I upgraded a county PSAP. New consoles (Moto Gold Elite), voting system and misc other RF updates/additions. All installed per Moto R56 (At least what R56 was at the time) Master ground bar and subsystem ground bars within PSAP. Offered all vendor equipment availability to ground to ground bars as long as they were compliant (Proper gauge wire, green jacket, irreversible connectors etc) The 911 vendor did NOT connect CPE to site ground system. Fast forward several years. Adjacent tower (~ 120' from dispatchers) was stroked, hard. Top antenna was cleaned out (IE No center pin and interior damage). Jailer couldn't hear for several hours. But no damage to RF equipment, CEB or clients. Everything kept going without a blink, EXCEPT 911 equipment. All clients were lost and damage to backroom premise equipment. The county had to transfer 911 to neighboring county for 3 days.

Several weeks after the incident, the PSAP admin told me that when initially installed, he questioned the cost and effectiveness of the protection equipment, bus bars and "All of that green wire". (In his head, but never verbalized it) After this incident, he no longer questioned and whatever it costs, it was worth it.

 

[prcguy]

As a general statement I will say its not possible to make a home antenna setup lightning proof within reasonable financial means. You can but its going to cost more than anyone I know could spend. If you are building a house from scratch then you can do all the things that cell and repeater sites do to make them lightning proof, at a huge cost of course and your neighbors may not like it.

Its better to know you can't survive a direct hit and disconnect everything before a storm arrives over cobbling some things together and thinking its going to save you, which it will not. And if someone tells you to add this lightning protector or that prickly thing on the top of your tower and it will save you, ask them if they will pay for all the damage if their recommendation didn't work. That right there is the bottom line, anyone who gives specific lightning protection advice should own the consequences if it doesn't work.

I would be curious, and I am being serious here, what you suggest as the basics that a hobbyist/ham should have for a VHF/UHF station? I have basic lighting arresters (which I know won't stop a direct hit...) that are grounded but I've also read people say that they are pointless since, as I said, they won't stop a direct hit. Obviously there are other reasons to have it but for those who stumble across this and wonder "well, what should I have...?"...what would you tell them?

 

[mmckenna]

I would be curious, and I am being serious here, what you suggest as the basics that a hobbyist/ham should have for a VHF/UHF station? I have basic lighting arresters (which I know won't stop a direct hit...) that are grounded but I've also read people say that they are pointless since, as I said, they won't stop a direct hit. Obviously there are other reasons to have it but for those who stumble across this and wonder "well, what should I have...?"...what would you tell them?

That's a complex answer, and it would depend on the individual install. Proper grounding is an entire field of study on it's own, and no way I could cover it all in a thread on a hobby site. That would require a huge amount of bandwidth and someone with specific training (that I don't have). R56 is your best primer.
What I was replying to is those that will say they "don't ground anything and I've never had an issue". Or worse, "I don't ground anything because it just attracts lightning".
Those approaches are not a sign of skill or knowledge. It just shows they've enjoyed a run of good luck, and as we know, that run often doesn't last.

 

[kayn1n32008]

@jim202

tower had little grounding. Yes the legs are bonded To the base. No halo at the base. The shelter is 2 metal, weatherproof cabinets mounted on the base. The base is 3x 8” screw piles with a plate steel frame. Tower is free standing, there are no guy lines. There is 2 phone lines that come into the building, nothing was lost on the phone lines. This site is fibre optic fed, and none of that Fibre gear was damaged.

All in all it is poorly grounded, as evidenced by the photos posted here. I didn’t get photos of all the cooked components. I will get some photos of the satellite dish proximity to the tower, cabinets and tower base later today.

 

[kayn1n32008]

That's a complex answer, and it would depend on the individual install. Proper grounding is an entire field of study on it's own, and no way I could cover it all in a thread on a hobby site. That would require a huge amount of bandwidth and someone with specific training (that I don't have). R56 is your best primer.
What I was replying to is those that will say they "don't ground anything and I've never had an issue". Or worse, "I don't ground anything because it just attracts lightning".
Those approaches are not a sign of skill or knowledge. It just shows they've enjoyed a run of good luck, and as we know, that run often doesn't last.

I lived in that house for just shy of 6 years. Always wanted to see a direct strike(just to see it) two weeks after we moved into our new place it took a hit

 

[kayn1n32008]

This is the base of the tower. The enclosure on the left side, attached to the lower cabinet is the power, that had the door blown off, enclosure on the upper cabinet, on the right is where the fibre comes in. I own the white place in the back ground, it’s about 60m from the tower.

 

[mmckenna]

I lived in that house for just shy of 6 years. Always wanted to see a direct strike(just to see it) two weeks after we moved into our new place it took a hit

I believe the saying goes something like:

"Man plans, Thor laughs, and then throws a thunderbolt at your @**"

 

[CCHLLM]

There's also an old saying in a very old amateur radio text from the 1930s: "Lightning has only one agenda, and it has absolutely no regard for the feeble measures that man may create to quash that agenda. You may delay its mission, but sooner or later, lightning will have its way."

 

[jim202]

Those of us that have grown up with the guide lines from the R56 standard have grown custom to doing grounding that way. Working for about 4 different cellular companies over the years, they all do it the same way with very little minor differences.

Not being able to actually look at the tower location that Kayn32008 has provided the photo of, even though the tower may be sitting on screw anchors, if I caught the description, they don't provide enough of a low ground resistance to provide adequate low resistance grounding.

I will give an example of a site that had 2 each, 500 foot guyed towers. The site was both a cell site and a paging site. both towers were within 20 feet of each other. The grounding ring around both towers was installed correctly. This was affirmed by actually digging up the soil and inspecting the ground ring. After some brain mashing back in the office, it was decided that the damp clay soil could not dissipate the direct hits the towers were taking. So we dug a trench away from the towers in opposite directions for 100 feet. Added a new ground rod every 16 feet and exothermically welded them to the ground wire in each new trench. Attached the new ground wires to the ground ring around both towers.

Before the ground wire additions, there were what are called sneak fuses in series with the phone lines coming into the paging transmitters. They were always blowing and protecting the paging and cellular connections to the phone company. After the ground radials were added, no more problems. So this goes to show, that even after installing grounding per R56 standards, you might have to go even further. It will depend on the soil conditions at your tower site.