Who else [RE-wrenches]/lightning protection

[Sharkey]

	Hi Clive;

	I agree with you, too many rules and restrictions spoil the soup.

	As for your lightning problems. Be sure to ground the hell out of your
equipment. You are probably already doing this, but I'm talking about
several ground stakes in a circle, connected together with wide copper
strap. This is called a ring ground, and it is usually installed outside
the perimeter of the building the equipment is installed in. Copper straps
radiate inward from all corners to the equipment racks. Ground your towers,
PV arrays, and anything else that's metal. Copper strap ground radials
buried about 6" deep and 10 meters long leading away from your ring ground
system makes it even better.
	Now that you have produced the best ground in the neighborhood to attract
all the lightning, let's concentrate on keeping it out of your equipment.
	Spark gaps are the first line of defense. Commercially made spark gaps are
available, but I doubt that they are any more sophisticated than home made
units which use automotive sparking plugs. The center conductor of the plug
gets connected to your wiring and the shell is securely grounded. They must
be mounted in a proper enclosure to prevent shorts, shocks, and bugs from
building nests on them! Use brand-new ones, as used plugs will be worn and
have oily deposits. Place spark gaps at each end of any run of wire that
enters/exits the equipment building. More gaps = more protection.
	A very cheap and effective way of discouraging lightning is to place a 1
meter diameter loop in every wire that enters the equipment building. This
loop should be in free air, and the ends of the loop should not touch each
other physically. Lightning has a very fast rise time and behaves much like
radio frequency energy. The inductance of the loop will help the lightning
look for another path to ground.
	Ferrite cores can be very helpful for the same reason. Place ferrite
torroids on all wiring entering or leaving the equipment building.
	Best of all (but not cheap) is to prevent lightning from striking you at
all. Commercially made static dissipator arrays can protect your PV's and
wind equipment from even being hit in the first place. These consist of a
"crown of thorns" or straight rows of sharp metal spikes, much like large
stainless steel thistle heads. Their job is to dissipate static buildup
before a corona is formed and thus prevent the ionization of the
surrounding air, resulting in a strike. One maker of this product is
"Stati-Cat" by Cortana Corp.

	As a Broadcast Engineer, I have used all of these methods, and so far have
been very lucky to have lost only a small bit of equipment to severe
lightning striking our 415 foot tall tower. At our FM site, lightning has
melted solder after hitting the radiating elements of our antenna, and
fused de-icer wiring inside the conduits, but never so much as a damaged
diode inside the building.
	Good luck, stay in touch.

	-S

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