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Author Topic: Unhooking Station Equipment Before A Thunderstorm  (Read 4280 times)
AK4SK
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Posts: 150




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« on: May 15, 2013, 09:20:16 AM »

This is a hotly debated topic I think, whether or not to unhook your radio and other equipment when there is a chance of lightning. I currently unhook and unplug everything when I think that there is a chance of lightning. I know that a lot of people, and a lot of professional sources, say that this is not a good idea. My understanding is that unconnected coax terminals or unconnected coax cables are at risk of arcing and starting a fire if your station is hit. What I don't understand is why the alternative, keeping all of my expensive equipment connected, is any better.

For one, any given house has many unused cable TV jacks and electrical outlets. Don't these present just as high of a risk of arcing if if the cable or electrical service is hit by lightning? I'm not going to go plug a TV into all of them am I? Also, my radio and other equipment is not designed to be a proper load to dissipate a lightning strike. To me there is a good chance that my radio could catch on fire just as easily as an arc from a disconnected coax cable or coax jack could cause a fire. If that is the case, what then is the advantage of leaving your station at risk from damage?

Thanks and 73,
Chris AK4SK
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K1CJS
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« Reply #1 on: May 15, 2013, 09:56:57 AM »

If you get a direct hit by lightning, you're going to have some damage.  Even if your ground system is robust enough to dissipate the strike, there is still going to be damage of some nature.  Luckily, most 'strikes' are near misses, and the better a grounding and suppression system you have, the more you can avoid damages to your equipment because the voltage 'spike' that a near miss induces in the co-ax lines still has to go somewhere. 

If the method you employ is disconnection of your equipment, you had also best get the ends of the leads out of your house/shack, because you're right--just leaving them laying on the floor is just as dangerous as leaving them connected to the equipment.  If you have a good suppression system, the charges drain through the suppression system, if not, then they may jump to some ground around your shack area--including the house electrical system.

If you insist on the disconnection method, best that disconnection be done at a bulkhead where the co-ax lines enter the house/shack and the ends of the co-ax lines be put as far from the house/shack as they can be.  The only trouble is that that method is dangerous as well, because most of the time the disconnection is done when a storm is near, and the lightning can jump ahead of the storm by many miles.  If you insist on doing things that way, the best thing to do is to connect your station ONLY just before you're going to be using it--and disconnect it immediately afterwards. 
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W9KDX
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« Reply #2 on: May 15, 2013, 11:28:36 AM »

I can't see how this would be hotly debated.  I do exactly the same thing if there is even a chance of rain.  The coax is disconnected at the bulkhead and all electrical connections to any equipment are unplugged.

My equipment then has the same risk as it does in a box in a closet and I have the additional grounding I installed.  I remember the damage a house close to me had when the house next to him was hit.  All the protection I might install is worthless if the strike next door comes through my power lines.
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Sam
W9KDX
AK4SK
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« Reply #3 on: May 15, 2013, 11:33:37 AM »

I can't see how this would be hotly debated.  I do exactly the same thing if there is even a chance of rain.  The coax is disconnected at the bulkhead and all electrical connections to any equipment are unplugged.

My equipment then has the same risk as it does in a box in a closet and I have the additional grounding I installed.  I remember the damage a house close to me had when the house next to him was hit.  All the protection I might install is worthless if the strike next door comes through my power lines.

Do you unhook at the outside bulkhead or the inside bulkhead?
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KJ4JQU
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« Reply #4 on: May 15, 2013, 11:44:49 AM »

Fortunately I have never had to test this- but I unplug my main ant feed line from the tuner and but the connector inside an empty (glass) 5th of bourbon. It's then insulated . Don't know where I picked that up( probly on here). And I unplug my power strip that runs my whole rig.
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AA4PB
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« Reply #5 on: May 15, 2013, 12:12:03 PM »

The coax shields should be grounded outside just before they enter the house whether you disconnect the radios on the inside or not. If you don't have a path to ground outside the house then your coax cables will bring the lightning currents inside. A glass jar isn't going to provide enough insulation to stop lightning - in fact it may cause glass splinters to be thrown across the room.

If your coax is not grounded then it needs to be disconnected and taken outside the house during a lightning storm. Personally, if a storm is comming I wouldn't want to be touching cables disconnecting or moving them. Lightning has been known to strike far in advance of the actual storm.

Provided that grounding is properly handled, there is nothing wrong with disconnecting the equipment to provide extra protection for it. But again, you don't want to be handling the cables during an upcomming storm!
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K5LXP
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« Reply #6 on: May 15, 2013, 02:06:22 PM »

There will always be that one time you won't be home to disconnect the lines, and/or you will be unaware of an impending strike.  Your disconnect system has numerous failure conditions but surge protection works 24/7/365.


Mark K5LXP
Albuquerque, NM
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W9KDX
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« Reply #7 on: May 15, 2013, 03:30:43 PM »


Do you unhook at the outside bulkhead or the inside bulkhead?

I unhook inside for two reasons.  First, I assume that my multiple grounds and surge protectors need to be connected to the outside coax to work.  Secondly, I'm in MN so it is a bit cold sometimes to be climbing up the the bulkhead.  Also, to avoid the issues mentioned before, with an inside disconnect, I can ALWAYS do so easily if there is any chance of bad weather.  Most of the storm season up here, I just disconnect automatically each time I leave the shack.  It makes for much more peaceful sleep when I hear a clap of unexpected thunder at 3 AM.
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Sam
W9KDX
K4SAV
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Posts: 1847




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« Reply #8 on: May 15, 2013, 05:26:49 PM »

Disconnecting your equipment is not a substitute for good grounding.  If you don't have proper grounding you will probably have damage whether your rig is disconnected or not.  It might not be your rig that gets damaged but most everything else in your house.  Never disconnect coax or ground wires outside the house.  That just makes your grounding system not work properly.  If you want to disconnect your equipment inside the house, go for it.  If you don't have proper grounding, unhooking the cables outside the house isn't going to do much for protecting you.  That just allows lightning to choose whatever path it likes.

Jerry, K4SAV
« Last Edit: May 15, 2013, 05:41:33 PM by K4SAV » Logged
WB6BYU
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Posts: 13335




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« Reply #9 on: May 15, 2013, 07:16:54 PM »

When a lightning strike has already arced across a couple miles of air, what is the
likely hood that a few more feet between the socket and the disconnected plug is
going to stop it?

Disconnecting adds a little bit of extra protection, with some added risk.  It only
works if you are ALWAYS home and awake when a storm comes through.  And
when a storm is approaching is NOT the time I'd want to be holding onto my
coax trying to disconnect it:  I've seen the arcs across the variable capacitor
in my antenna tuner even when we couldn't hear any thunder.

If you want to protect your equipment by disconnecting the antenna lead, do
so AS SOON AS YOU FINISH OPERATING, rather than waiting for a storm.  Bring
your coax to a proper ground system OUTSIDE the house where the shields
are grounded, then disconnect the jumper from there to where the coax passes
into the house.  Disconnect at the house end and lay the coax on the ground
as much away from the house as possible.
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KH6DC
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« Reply #10 on: May 15, 2013, 07:40:24 PM »

I have a lightning arrestor on my antenna and good surge suppressors for the linear and power supply but I always disconnect my equipment when three's thunderstorm warning for the entire island.
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73 and Aloha,
de Delwyn, KH6DC
K0ZN
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Posts: 1553




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« Reply #11 on: May 15, 2013, 08:02:28 PM »

Hi.

First, those taking the position that you may fail to disconnect are CORRECT.  I *try* to disconnect but there have been cases when I got distracted, etc.
and didn't get it done and had some white knuckle moments during some storms. We have very severe lightning around here in the spring severe weather season; strokes that make AWG # 2 look really small !  I absolutely do not want lightning coming in the house, consequently, I have a bulkhead plate ground OUTSIDE the house for those antennas with coax and my ladderline antenna is disconnected and grounded to the same point OUTSIDE. Inside, I disconnect the coax from the rig and connect it to a heavy ground cable. I also pull and disconnect ALL AC power connectors. The AC power line is a MAJOR source of residential lightning damage.

A lot of people want to leave the rig connected all the time for convenience..... that is a choice. My take is that this is a HOBBY. I do not need nor want to be on
the radio when there is lightning in the area. The hassle to me is a minor inconvenience compared to the much improved lightning protection I get by keeping
cables and ladderline disconnected and grounded outside the house. Again... this is a HOBBY and I prioritize accordingly.  "Different strokes for different folks...."
 
You must religiously disconnect after ALL and any operation if you want to minimize the chance of human error. I actually have a homemade red/green reminder that I keep at the operating position just to make sure I am aware of the status of outside grounding.

Disconnecting and grounding outside IS the best way to keep a hit to your antenna from entering the house, rig, etc. IF you do ground the transmission lines out there, that program is only as good as you make it......and you absolutely do not want to try to disconnect and ground when lightning is already in the area and that is the
best argument for other types of protection IN ADDITION to disconnect and ground. You also MUST have a large, effective
ground system at that outdoor ground point and ideally, that should be your single point ground. Lots of people don't want the inconvenience of disconnecting....that is a choice but requires more protection.

 The worst case is disconnecting and leaving the coax line "floating" ungrounded.  That is begging for a disaster.

Regardless of best efforts , a major hit by a large bolt can yield unpredictable results. We are talking MEGA watts and MEGA volts here.....  Obviously, if money is not an issue, you can develop a protection system that is pretty much bullet proof, but for most hams, there is some limit to money, and disconnecting and grounding outside
will go a long way toward reducing problems indoors.....note I did not say "guarantee" !
.

73,  K0ZN


« Last Edit: May 15, 2013, 08:12:43 PM by K0ZN » Logged
KC8HQX
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Posts: 177




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« Reply #12 on: May 15, 2013, 09:46:51 PM »

The National Electrical Code specifies all equipment must be tied to a common bond ground for a reason. It is the voltage differential during a (near) strike event that destroys equipment. Most hams can't afford a ground system that can take a direct hit, but even so, there's no better protection than a solid, common bond ground system. Also, just try to get an insurance check after an event if the inspector discovers your system violates electrical code


When you start disconnecting things, you introduce the chance for lightning to take different paths, introducing voltage differentials. It might not be your antenna that's the source; it could be the CATV, phone, power, etc. EVERYTHING should be tied so the "rising tide lifts all boats" equally. Done right, a direct strike to your antenna will be dumped to one of your ground rods before entering the house. Even without a direct strike, the EMP from a nearby event can and will wreak havoc on any equipment left floating. There are plenty of stories of fellows seeing their disconnected, ungrounded feeds arcing and snapping like mad during storms - wind alone can generate a wicked charge on an ungrounded antenna.

ICE Inc. has some good guides here: http://www.iceradioproducts.com/10.html and some other great resources are available here http://www.repeater-builder.com/ge/lbi-library/lbi-39067a.pdf here: http://members.rennlist.org/warren/LightningProtectionAndGrounding.pdf  and links contained here (some redundant, all were valid last time I checked) http://arvideonews.com/hrn/HRN_0015_W4TL_Reference_Handout.pdf

The info in the above resources will all tell you roughly the same thing - bond and ground all of it!

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KC4MOP
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« Reply #13 on: May 16, 2013, 03:28:01 AM »

Always some very good advice here. It's Summertime and disconnect (Antennas and power) after operating is the best you can do.
If I was not handy in replacing and sourcing what happened to us, end of last Summer, we would have had an out of pocket expense of $1200 from damages from a nearby strike.
The storm came up fast on us and I couldn't power down or turn things off fast enough. I was running up the steps from the shack to start "saving" equipment and it was too late. The lightning was close and the wood burning stove made a snap sound. Discharging I guess. We lost our LED flat screen, it WAS turned off, 2 computers, Ethernet connection/card destroyed, my Flex SDR 1000 radio and another computer developed major mother board problems this past Winter.
Whatever it was came in on the ground side (not protected, but grounded now) of the satellite dishes or the Comcast Cable for our internet. All  these issues are now properly grounded with new 8 foot rods on the tower and all of the RG-6 coax entering the house. The Ham antennas have always had their own protection installed before entering the house. The Ladder Line is on a huge knife switch and that is always disconnected when not in use.
Fred
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K1CJS
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« Reply #14 on: May 16, 2013, 04:02:14 AM »

Do you unhook at the outside bulkhead or the inside bulkhead?

If your entry bulkhead is a properly grounded bulkhead, disconnect inside.  If it is a plate that is mounted in a window area without proper ground, then disconnect from the inside--and take the plate out of the window area and toss it on the ground away from the house.

The idea is to keep the charge--and any discharge arc out of your house/shack. 

There again, if you have any sort of antenna system connected through such a 'window feed through plate' without having the antenna systems grounded, you had better rethink your protection plan for the simple reason that even with no storm in sight, any antenna system can still pick up static charges that could come in through the antenna connection--and ruin your equipment anyway.
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