tIS' the season, PSA. (Antenna grounding, RR should sticky it for a while)

[wowologist]

In our hobby we like to stick metal objects high up into the air ~
YOU *NEED* to stay on top of YOUR grounding situation!!! SAFETY SAFETY SAFETY!!

Here are some pics of what happened when the 'hood had a nearby lightening strike. Now keep in mind the actual strike location was ~1000' from this location. This was just an arm/arc of the main strike that literally obliterated a rather large, really old oak tree.

This was a downlink coax run from a DirecTV sat @ approx 12' above ground. As you can see it served it's purpose (and was destroyed in the process) - the Fire Insp. that came by said it did it's job very well, as if it had not been installed properly, it could have energized the metal rain pipe/gutter system, as well as directly energizing metal components inside the house that people may have been in contact with, causing..well, we'll leave that to Hollywood.

Keep in mind that this is in a normal metro SFH hood with power poles, and ton's other higher objects and ground points. LIGHTNING GOES WHERE IT WANT'S TO!

 

[mmckenna]

What's worse is that we have amateurs (who should know better) that don't understand this stuff.

Seems like safety is the first thing that gets cut from the budget.

 

[a417]

Obligatory Mr Carlson's Lab video about sparks jumping gaps during a snow storm.

 

[mtindor]

What's worse is that we have amateurs (who should know better) that don't understand this stuff.

Seems like safety is the first thing that gets cut from the budget.

That's because most hams are cheap, extremely cheap. I'm a ham. I know hams. I speak the truth lol. And you can pretty much bet that if you hear a ham buying a cheap chinese radio, it's nearly 100% probability that if they have a shack / external antenna, there is no grounding in place. Hell I know many with thousands of dollars invested in equipment who don't bother to ground.

I don't have anything up in the air right now, but I'm ashamed to say that in 29 years that for which I had a shack and external antennas most of the time, I did NOT do anything with grounding either. When i do get some new equipment and put up an antenna, I won't neglect grounding.

m

 

[mmckenna]

Hell I know many with thousands of dollars invested in equipment who don't bother to ground.

I've heard it many times on this site. "I've had my antennas up for XX years and never had an issue". Confusing luck with skill/knowledge is dangerous.

 

[tweiss3]

That doesn't look like an adequate ground wire. 10GA or larger per NEC.

 

[prcguy]

The ground wire or "messenger cable" imbedded in some RG-6 is 17ga copper clad steel and legal per NEC. Looking at the pictures in the first post, that cannot be from a strike 1,000ft away, there would have been a stringer from that strike that touched the DirecTV install.

In the old days when a DirecTV installer arrived at your house he had two things to verify before mounting the dish, a good view of the satellites and less than about 30ft of wire length to the house main ground point.

That doesn't look like an adequate ground wire. 10GA or larger per NEC.

 

[wowologist]

"that cannot be from a strike 1,000ft away, there would have been a stringer from that strike that touched the DirecTV install. "

huh?

What are you calling a stringer...the other side of the cable goes under the house where it is bonded to a 1/2" copper water pipe (and then proceeds to the interior equipment) which then has a bonding clamp to a copper 8' ground rod, which is located to the right of the building at it's corner ....the top of the cable (blocked by the gutter) is a grounding block which is bonded to the antenna mounting plate and then proceeds upward without the ground wire, into the BUC housing. This, along with 7 others houses all had similar strikes. And if you look at the top picture, the cable from the antenna mount to the BUC, is actually untouched, but from the bonded grounding block down is where the discharge occurred.

 

[richwig]

"that cannot be from a strike 1,000ft away, there would have been a stringer from that strike that touched the DirecTV install. "

huh?

What are you calling a stringer...the other side of the cable goes under the house where it is bonded to a 1/2" copper water pipe (and then proceeds to the interior equipment) which then has a bonding clamp to a copper 8' ground rod, which is located to the right of the building at it's corner ....the top of the cable (blocked by the gutter) is a grounding block which is bonded to the antenna mounting plate and then proceeds upward without the ground wire, into the BUC housing. This, along with 7 others houses all had similar strikes. And if you look at the top picture, the cable from the antenna mount to the BUC, is actually untouched, but from the bonded grounding block down is where the discharge occurred.

Prcguy may have using "stringer" as describing a secondary lightning discharge that branched off the main stroke and hit this antenna.

The cable above the grounding block is OK because it's bonded to the dish mounting pipe, which carried most of the current. Below the block, that 17-gauge wire was more or less a fuse. A 10-gauge or thicker copper cable might have fared better. The dish industry must have really kissed the code-making panel to get 17-gauge messenger cable approved for bonding. That thin of a wire would present a lot more impedance to lightning energy that a wire with a larger surface area.

I would wager if that CAT6 cable were unshielded, the equipment on either end would have been blasted by the EMP that stroke would have induced into the cable. I have cleaned up after events like that.

 

[SurgePGH]

In our hobby we like to stick metal objects high up into the air ~
YOU *NEED* to stay on top of YOUR grounding situation!!! SAFETY SAFETY SAFETY!!

Here are some pics of what happened when the 'hood had a nearby lightening strike. Now keep in mind the actual strike location was ~1000' from this location. This was just an arm/arc of the main strike that literally obliterated a rather large, really old oak tree.

This was a downlink coax run from a DirecTV sat @ approx 12' above ground. As you can see it served it's purpose (and was destroyed in the process) - the Fire Insp. that came by said it did it's job very well, as if it had not been installed properly, it could have energized the metal rain pipe/gutter system, as well as directly energizing metal components inside the house that people may have been in contact with, causing..well, we'll leave that to Hollywood.

Keep in mind that this is in a normal metro SFH hood with power poles, and ton's other higher objects and ground points. LIGHTNING GOES WHERE IT WANT'S TO!

View attachment 95539View attachment 95540View attachment 95541

That is NOT intended to be a ground wire. Nope. No Way. That is "Messenger Wire" and it is not a proper ground in this example. The messenger on this cable is intended to support the coax in an overhead style installation.

 

[prcguy]

Yes, I was referring to an actual branch of the lightning hitting the DirecTV system somewhere. You can't induce that much current from 1,000ft away to cause that much damage. I've had a hit in my neighborhood less than 1,000ft away and it took out some diodes in an SGC auto tuner I had at the top of a tower with 100ft of antenna wire connected. You can get quite a bit of voltage induced on that much wire but there is very little current.

On the other hand someone I know did get a direct hit on one of his ham antennas and it took out everything in his house, including an HF radio stored on a shelf disconnected from anything. It either arced around stuff in the room and the radio bridged the arc from one point to another or if there was a mic connected and the mic cord could have had a lot of voltage induced onto it from the close proximity.

Prcguy may have using "stringer" as describing a secondary lightning discharge that branched off the main stroke and hit this antenna.

The cable above the grounding block is OK because it's bonded to the dish mounting pipe, which carried most of the current. Below the block, that 17-gauge wire was more or less a fuse. A 10-gauge or thicker copper cable might have fared better. The dish industry must have really kissed the code-making panel to get 17-gauge messenger cable approved for bonding. That thin of a wire would present a lot more impedance to lightning energy that a wire with a larger surface area.

I would wager if that CAT6 cable were unshielded, the equipment on either end would have been blasted by the EMP that stroke would have induced into the cable. I have cleaned up after events like that.

 

[prcguy]

The 17ga messenger wire in some RG-8 is a legal ground wire, that's why its 17ga as required by NEC and its copper clad steel. Its primary purpose is to take the strain of an overhead run off the braid and other parts of the coax. The reason I know this is because I was an SBCA certified instructor for residential satellite installers and it was on some of the tests.

From NEC:
The Mast Ground
Article 810 says the mast must be grounded using one of the following conductors. (810.21(H))

• 10 Gauge Copper Wire -Solid or Stranded, Insulated or Bare
• 8 Gauge Aluminum
• 17 Gauge Copper clad Steel or Bronze wire

That is NOT intended to be a ground wire. Nope. No Way. That is "Messenger Wire" and it is not a proper ground in this example. The messenger on this cable is intended to support the coax in an overhead style installation.

 

[wowologist]

Well ALL the comments/suggestions are awesome and informative when you have a subject such as this, we all learn things AND hopefully will get a grip on the life safety necessity of grounding, properly. Stuff like this as mmckenna stated above, is pure luck that it hasnt happend TO YOU>>>YET. That's why I posted! This is the way.

In this case, like the Fire Inpst. stated it did it's job and did it well. If it hadn't' my Samsung QN85Q60T 85" (OP don't buy one and the associated attached A/V components may have received the incoming surge and may just have created a fire. Which at the time of night that this happened, may have smoked more then just the equipment.

 

[scannerowner]

I've been wanting to put antennas up, but worried about lightning. I thought about getting one of these with the lightning surge protectors. I'm still worried about lightning strikes though.

https://www.hamradio.com/detail.cfm?pid=H0-012783

 

[mmckenna]

I've been wanting to put antennas up, but worried about lightning. I thought about getting one of these with the lightning surge protectors. I'm still worried about lightning strikes though.

It's good to be concerned. That means you'll likely do it right the first time.

Those buss bars are a good option. They use a bigger/heavier version of that at most commercial sites. The Polyphaser units are bolted to the buss bar.

Depending on what your skill level is, there's no shame in hiring an electrician to run in a new ground rod and bond that to your home ground. It's not a huge job if they have the right tools (ground rod driver).

 

[prcguy]

The chances of you completely protecting your equipment from a direct lightning hit at home is about zero. I'm not kidding. So going into the process of adding lightning arrestors, ground blocks, etc, knowing there is no guarantee will force you to adopt procedures like disconnecting the antenna and unplugging equipment when lightning is approaching.

I've been wanting to put antennas up, but worried about lightning. I thought about getting one of these with the lightning surge protectors. I'm still worried about lightning strikes though.

https://www.hamradio.com/detail.cfm?pid=H0-012783

 

[scannerowner]

I want to be able to listen and transmit during weather events. We are wanting to remodel the house, so I have thought about getting an electrician's experience for grounding it. It seems easy to do the buss bar with the protectors on it.

 

[bill4long]

I've been wanting to put antennas up, but worried about lightning. I thought about getting one of these with the lightning surge protectors. I'm still worried about lightning strikes though.

Surge protectors, polyphasers and ground rods are very useful for close indirect strikes, but useless for direct strikes. (In fact, a ground rod may increase your chance of a direct hit.) A direct hit is going to cause total destruction of the antenna and whatever is connected to it. And possibly worse. There is risk involved in putting up any external antenna. Luckily the risk is usually low for smallish antennas mounted on homes. Thankfully direct hits are not all that common.

The energy level of the average lighting bolt is about 300 billion joules of electrons. (Think of 300 billion watts flowing for one second.) They are nasty beasts. Direct hits are unpleasant affairs, esp if you have anything connected to the antenna, and any counter measures you are likely to afford are useless in direct hits.

Go ahead and use the counter measures. But if you want maximum protection, unplug your external antenna from your radio in a lightning storm. Otherwise, leave it plugged in, understand that a direct hit is very unlikely, and take your lumps if a direct hit actually happens.

 

[scannerowner]

Thanks for the info! I was looking at 4' tall antennas mounted on the chimney. I have 4 pine trees around the house. They may be taller than the antennas anyway.

 

[prcguy]

Antennas with Polyphaser protectors can and do survive direct hits all the time, every day somewhere. If the entire grounding system is designed to handle a direct strike. A USCG repeater antenna I've spoken of before that was destroyed twice by direct hits had a properly installed Polyphaser arrestor in the feedline and it survived just fine and protected the equipment downstream. But the massive tower and ground ring around the purpose built repeater site building took the vast majority of the current as it should.

At home you should do what is mentioned below.

Surge protectors, polyphasers and ground rods are very useful for close indirect strikes, but useless for direct strikes. (In fact, a ground rod may increase your chance of a direct hit.) A direct hit is going to cause total destruction of the antenna and whatever is connected to it. And possibly worse. There is risk involved in putting up any external antenna. Luckily the risk is usually low for smallish antennas mounted on homes. Thankfully direct hits are not all that common.

The energy level of the average lighting bolt is about 300 billion joules of electrons. (Think of 300 billion watts flowing for one second.) They are nasty beasts. Direct hits are unpleasant affairs, esp if you have anything connected to the antenna, and any counter measures you are likely to afford are useless in direct hits.

Go ahead and use the counter measures. But if you want maximum protection, unplug your external antenna from your radio in a lightning storm. Otherwise, leave it plugged in, understand that a direct hit is very unlikely, and take your lumps if a direct hit actually happens.