Sometimes it takes an unforgetable event to make us pause from our seemingly endless busy days, and consider some things we would normally dismiss as unimportant.  This is what happened to me and my work colleagues yesterday morning...

For those readers who do not know anything about me, I am a Radio Technician, and am based in a radio workshop in rural New South Wales along with my work colleagues.  Our workshop is similar to any Radio Workshop in Australia, having a main room loaded out with work benches, Test Equipment, Computers, tools, Soldering Stations and Two-Way Radios.  We have a 20 metre concrete pole located to the rear of our building, which is loaded with various antennas for the different services we provide and monitor.  All co-axial feeder cables enter our workshop via a bulkhead plate, fitted with lightning surge supressors, earthing kits and electrically bonded to a common earth point outside our building.

You may now be wondering why I am describing my workshop to you, and what relevance this has to this artical's title.  I am just setting the stage for the events that came next...

In our line of work, designing radio sites that will continue to operate without failure is a high priority.  As Radio Technicians, we are all to familiar with the effect that a direct hit by lightning can cause to the sensitive radio equipment at the site.  Due to the likely chance that an antenna atop a tower, and atop a mountain, would be hit by lightning, we go to lengths to ensure the lightning is directed to ground, bypassing any electronic equipment.  We also adopt the same approach when installing antennas on the tower behind our workshop...

Yesterday morning, just before lunch, we heard some distant thunder and didn't think too much of it at the time.  However, moments later, it felt like a bomb had gone off in our workshop.  With ears ringing, and the acrid smell of burnt electronics quickly filling the air, we were left stunned and in the dark.  We quickly realised that our workshop had received a direct hit by lightning!

I was very confused, as we had all industrial standard lightning protection in place on our cables.  In the few hours that passed, we were able to trace the lightning's path, and discovered some very interesting facts that everyone should be made aware of.

The first photo shows the top of our concrete pole, and the point that the lightning hit on our top colinear antenna.  From there, hundreds of thousands of volts pushed an enormous current down the feeder, through the lightning supressor (our ones were a few years old) on the bulkhead plate, and down to one of our two-way mobile radios.  From there, it arced across from the antenna connector to the case of the radio internally.  Now, anything connected to our commonn ground was instantly raised thousands of volts above normal.  This current passed through the fuses on the radio's 12V DC cable, which exploded with such ferousity as to generate plastic, metal and glass shrapnel that had enough velocity to punch through a multi-page document (one picture shown).  The current then passed on to the 12V Power supply, which was happy to allow this surge onto our 240V mains circuit.  Any device connected to this circuit was fired, including three computers, two power supplies, two mobile radios and the list goes on.  When this surge reached our main distribution box, the earth leakage circuit breakers kicked in and it was prevented from going any further.  One of the computers that was hit was our main internet machine.  As a result, the ADSL modem was destroyed, and the surge current entered our internet network cables and also the phone lines.  One line survived, but the main phone line into our building was severely damaged.

We are all OK, but seconds before the strike, we were handling some of the equipment that was subjected to thousands and thousands of volts.  At the instant of the strike, none of us were touching anything other than our computer keyboards.

What have we learned?

Surge supressors are available practically anywhere, sold as dedicated devices, or bundled together with power boards.  We were protected from a surge on the mains power line, as there is adequate protection in the main distribution board.  We were not protected from a surge introduced on the mains circuits after the distribution board. We have learned that it is necessary to install these devices for each piece of electronic equipment in use.  We have also learned that having antenna cables entering a main work area is a bad idea.  I don't know of any workshop that I have seen that has its antenna cables entering via a secured room, for the purpose of lightning protection.  Lastly, we have learned the hard way that lightning can strike many kilometers away from the storm, and without warning!

In Conclusion:

Before you share the same experience as me, if your computers, TV, Stereo - anything plugged into the mains doesn't have surge supressors installed, please start investing in these devices.  They may not save your electronics, but would definitely help reduce a fatality to serious injury, if someone was handling the device at the time.  Also include the supressors designed for your phone lines.  If you, like many others, have HAM radios, scanners etc... set up in your garage or workshop, consider what would happen to you and the surrounding objects if a bright flash of lightning appeared where the cables enter your premises.

Feel free to share your thoughts and experiences...