I have seen several different lighting strikes. One example was a 4inh main in a local town. Lighting struck a near by tree and blew the pipe out of the ground according to the gas company they get calls like this every a couple of years.
Another one was lighting struck the ground about half way between a house and a propane tank that was 50 feet away. I remember you could see a burn pattern on the ground. With this one the lighting entered the house and blew the main breaker actually bunt it and started a small fire where the gas line entered the house. The strange thing about this one when the contractors dug up the copper gas line there where pin size holes in the line from the strike location to the house. And the line from the strike location to the tank looked fine.
Recently, I was talking to an old friend about a lightning strike. He said, "Remember what the old farmers used to tell you. Only the houses that are not properly grounded have escaped the surge." In their logic, houses that are not connected to a grounding electrode system (GES) don't suffer the effects of a nearby strike. A direct hit is a different story.
We bond all gas, hot water, and cold water pipes when possible. The NEC, also, requires bonding the water pipe with 5 feet of entrance into the premises. For many years, the water pipe was the main grounding rod, and additional rod(s) were added on and their names were changed. (supplemental to auxiliary) With the popularity of plastic, the water pipe bonding is being replaced by additional ground rods, and other grounding methods (UFER, for one).
Lightning is a tremendously huge, and devastating force. Any of the prescribed methods to reduce its damage to your property are well worth it.
A nearby hit can also be a direct hit. An example. Lightning struck the nearby tree. Any campers sleeping pointed at that tree required emergency medical treatment. Anyone sleeping tangent was unharmed.
Originally Posted by WaterholeWally
Lightning is current seeking distant charges. The path was down a tree, through earth, into the boy’s head, out his feet, then onward to those distant charges.
Any strike to wires down the street - a nearby strike - is a direct (destructive) connection to household appliances.
Nearby strikes may enter at one ground rod, pass destructively through a house, then exit via another ground rod. A nearby strike was a direct connection to household appliances because single point earth ground was not implemented. But again, what defines surge protection?
Another nearby strike: surges created by EM fields. Since it exists, then every car radio, cell phone, and wrist watch is destroyed by a nearby strike? Nonsense. EM fields from a nearby strike are made completely irrelevant by protection routinely inside all electronics. Protection even on the most sensitive transistor in every radio - the RF amplifier - makes nearby strikes irrelevant. But that reality contradicts popular urban myths. People want to believe a nearby strike is so powerful when over 95% of direct struck trees have no appreciable damage. The nearby strike is magnitudes less powerful.
A direct lightning strike to a lightning rod put the entire bolt on a ground wire only four feet away from a PC. The PC did not even blink. Those ‘hyped by myths’ EM fields are made trivial by protection routinely inside electronics.
Any nearby strike that might be destructive is made irrelevant by this protection also installed for direct strikes. To never have damage, telcos connect protectors on single point earth ground AND up to 50 meters separated from electronics. That separation increases protection - even from nearby strikes. Those who promote myths claim that 50 meters of wire induces destructive surges. How many times has phone service all over your town been lost for four days while they replace that computer?
We learn from the professionals who have been doing this stuff successfully for over 100 years. Damage from nearby strikes is mythical – or directly traceable to someone who did not install well proven 'whole house' protection from direct strikes.
Please, post your references for lightning activity and surge arrestor protection.
I am forever studying, and hopefully improving the electrical services that I work on everyday.
For FL surge prot.
2000 joules, per mode (per path of current)
4000 joules, total
80,000 amps, max
Insurance, $5k per item
$9/mon for a 10 yr warranty
design lifetime 10 yrs.
The present value of this annuity that you are paying to the FL PoCo at 7%/yr Cost of Money is worth about $750.
See Fig. 8.1
I've lived in zone 40 my whole life, never had surge protection and never lost anything to lightning.
An industry benchmark is Polyphaser. View their application notes at:
Originally Posted by WaterholeWally
But first, a basic concept based in what was taught in 2nd grade science, and that must be redefined so that everyone is working from the same science.
Lightning seeks earth ground. One conductive path was via wooden church steeples. Even wood is a conductor. However not a good conductor. The 10,000 amp surge through wood creates a voltage. Current times voltage means energy and the resulting damage.
Down the street, Franklin did not stop a surge. He simply gave lightning a more conductive path to earth. That same 10,000 amps has a more conductive path to earth. 10,000 amps times near zero voltage means near zero energy dissipated. No damage.
Protection is about diverting, shunting, connecting, conducting, or clamping that surge to earth ground.
Many view a lightning rod as protection. Few see the earthing system; do not credit what they do not see. A lightning rod is only as effective as its earth ground. Lightning rod connects the surge. Earth ground provides the protection.
Moving on to science well proven and demonstrated over the past 100 years. A surge protector does same. Anything that attempts to stop a surge only creates a massive voltage with destructive energy. Nothing stops that current. Voltage increases as necessary so that current will flow - an engineering concept called a current source. An effective protector does on all incoming utility wires what the lightning rod does for airborne lightning. Diverts. Provides a most conductive connection to earth.
Due to other complications (I believe Polyphaser app notes may discuss this), earthing must be single point earth ground. These concepts involve equipotential and conductivity. Both are necessary for effective protection. One says what a single point ground is. The other says why an earthing electrode system is expanded.
Due to wire impedance, an earthing connection must be short, no sharp wire bends, no splices, not through metallic conduit, etc.
Where energy is absorbed determines protection. That energy must be absorbed somewhere. That current will flow no matter what we do to stop it. Anything that attempts to stop a surge only increases voltage - therefore creates destructive energy. So that the least amount of voltage is created, worry about impedance; not resistance.
These concepts with examples were published in QST Magazine (the ARRL) in a three part series in June through August 2002. Another case study is described for a Nebraska radio station at:
Why they did what they did is not fully explained. Only that a solution always centers on earthing. If you grasp electrical concepts, then it becomes obvious (for example) why earthing was upgraded for the utility transformer. Why it addressed multiple potential problems. Above is necessary before many problems of obtaining equipotential and conductivity can be discussed.
Too many want to see a protector as protection. Protector is nothing more than a connecting device. That should be obvious in all three above citations. How good is a protector? How to make that same protector even better? Upgrade the earthing. Above only introduces concepts including the most important one: A protector is only as effective as its earth ground.
You must be a HAM Too!
Originally Posted by westom
Whats your call?
The industry benchmark is the IEEE; hopefully they don't sell equip. or have an agenda.
Not a HAM. But the basic electrical principles here involve RF electricity.
Originally Posted by yorktek37
For example, the third prong on a wall receptacle - the safety ground - does eventually connect to earth ground. But anything plugged into that receptacle is not earthed. Why? For electrical reasons that HAMs would understand and many electricians would not since each is trained in electricity with different characteristics.
How surges work and how shortwave radio and electricity works are quite similar. Principles that explained surge protection were learned by HAM radio operators even 100 years ago.