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Re: [IC-7000] Lightning Protection References


 

Jon,


The problem with unplugging everything is after a while, you tend to forget. ?Unplugging the coax from the tuner protects the radio, at the expense of the house, since even a nearby flash can transfer enough energy through the antenna to jump several feet and ignite objects. ?Plus, after a few hundred mating/unmating cycles, the contact resistance increases and you need to replace the connector in the radio or tuner, although you won't know that until after blaming a dozen other things for the flakey problems....


While the UPS unit is fine for line transients, they are ineffective as a primary defense for most lightning strikes, since the house wiring grounding impedance is too high to dissipate anything but a minor strike. ?A whole-house surge protector mounted at the service panel and grounded to the primary ground via a short #6 or larger ground wire is needed, then the UPS can absorb any let through voltage.


It's hard to make good recommendations without knowing more about your site. ?But to get started with a simple plan:


1. ?An unprotected feed line should never enter a dwelling. ?You need a lightning suppressor mounted on or connected to, an 8' ground rod. ?For just one lightning suppressor, you can take an Alpha Delta TT3G50 and screw its 1/4" threaded stud into a ground rod clamp instead of its wire clamping screw. ?That give you the lowest possible impedance to ground and simplifies mounting. ?Most hams have more antennas eventually, so then a ground bus bar is needed. ?See the photo at: ?http://www.alphadeltacom.com/ ? for an example.

I prefer Polyphaser suppressors, except for how they mount. ?I modify them to accept a larger bolt. ?I also use a stainless steel shim between the copper bus bar and aluminum suppressor, to prevent galvanic corrosion. ?


2. ?Run the antenna coax to the suppressor, then use another jumper from the suppressor to inside the house. ?Do not attach the unprotected coax to the house directly. ?You can tie it off with at least 2' of dacron or nylon rope if needed, to prevent arc-over to the house. ?Waterproof the coax connectors and the arc plug that screws into the top of the suppressor (even though they say it's waterproof). ?I use butyl self-fusing tape, applied over a layer of electrical tape (so you can remove the connector someday), with another layer of tape over the butyl to protect it from UV. ?There are other good ways, but just electrical tape isn't one of them.


3. ?The National Electric Code requires all secondary grounding connections to be connected to the primary electrical panel ground rod with at least #6 copper wire, using approved ground rod clamps (or other approved methods). ?This wire should be buried, if possible, about 6" below the surface. ?This protects it and greatly improves its ability to shunt current to the earth. ?You can buy 5/8" x 8' ground rods, clamps and wire at Home Depot, Lowes, etc. ?You do not usually need to be a licensed electrician or need a permit to install a simple ground wire, as long as you aren't modifying the primary ground rod or wiring to the electrical panel.

Ground wires used for lightning protection (as opposed to fault current safety) must never have sharp bends. ?Use at least a 6" radius bend. ?If attached to a structure, they must be secured every 3 feet (varies depending on local code, size of wire, etc.) to prevent the magnetic force of the current from a direct strike from ripping the wire off the building and severing the wire.


4. ?The ground rod clamp comes in several varieties. ?You don't want the $2 one. ?Get one rated for DIRECT BURIAL, as stated on the printed label attached to it. ?It will cost about $4.50. ?Don't use one that just squeezes the wire between the clamp and the rod. ?Get the split clamp with two bolts that hold the clamp together and a third screw to secure the copper wire. ?This third screw is the one you would replace with the stud of the TT3G50 suppressor, if you chose to go that route. ?Tighten all screws really tight. ?Then tighten them a little more. ?


5. ?A fence post driver is MUCH easier to drive rods than a sledge hammer. ?Ask around -- some ham will have one. ?They cost about $30-40.


6. ?If your soil is very rocky or there is hard pan a couple of feet below the surface, you need to consider different approaches, but I won't go into those for now. ?


7. ?I never use just one ground rod, even for a simple dipole. ?Add at least one more 16' away from the first, preferably along the run of wire to the electrical panel. ?If you live in a high flash density area like Florida, even more are worthwhile.


8. ?I personally don't unplug my feed lines from the radios usually, UNLESS I know a thunderstorm is likely or if I'm away from the house for days. ?When I unplug the coax inside, I plug them into shorting plugs mounted on the 2" wide copper strap that runs the length of my bench that is used for equipment grounds. ?This prevents any sparks from jumping around inside. ?A coax switch that grounds unused positions and the radio when the knob is in the OFF position is another option. ?Alpha Delta makes those also, although I haven't used them personally.


9. ?It is good to run a #6 copper ground wire (I use stranded, insulated wire usually here) from the lightning suppressor ground to the operating position. ?This serves as your single-point RF ground for the radio, tuner, computer, etc. ?Your radio and tuner usually have a designated grounding screw. ?Connect each unit to the ground wire from outside. ?Don't connect the radio ground, to the tuner ground to the computer ground then to the main ground wire going outside. ?Each unit has its own wire to the main ground. ?Many use a copper ground bus to attach the various unit grounds to. ?I use #6 or #8 insulated, stranded wire with ring lugs for runs to the units. ?Keep them short. ?Don't bother using flat braid, regular wire is just as good here.


10. ?Consider having an electrician install a whole-house surge protector if lightning damage is common in your area and you own the house. ?There are suppressors that replace an existing circuit breaker, which could be installed in a rental, but they would be a distant second choice, but better than a UPS. ?Otherwise, just leave your UPS plugged in. ?If lightning comes in on the utility line, your radio will be the least of your problems.


Feel free to ask questions or clarify details. ?Seldom are installations as simple as I assumed above.


Steve, W3AHL




---In ic7000@..., <jon@...> wrote:

Okay, Help.

?

One antenna 80 meter dipole at 35¡¯ hung from the trees.? Ladder line to the entry point on the house. 1:1 Balun and 10¡¯ of coax to the tuner.

When not in use, I unplug my UPS devices from the mains and I unplug the coax from my tuner.? Suggestions on anything else that is needed?

?

Now when I AM using the radios I have to UPS devices each rated pretty high for surge to power everything but I have nothing for the antenna as Im not sure what I could do.? Could someone offer an opinion that is simple?? I do not use the radio during thunderstorms or lightning within 15 or 20 miles and I live in a lower area with plenty of object taller than my antenna in the surroundings.? Wish I had a 200ft tower but still waiting for publishers clearinghouse to visit J

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Thank You

?

Jon

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