lightning protection

An FAQ here.. .

Don't neglect the modem - my mothers was trashed in a T-Storm only last month.

Ben Franklin demonstrated the concept in 1752. Lightning traveled miles through non-conductive air to obtain earth ground. Is some silly opto-isolator or point of use surge protector going to stop, block, or absorb lightning? Of course not. But effective protection has been demonstrated repeatedly since before WWII. Effective protection does what Franklin did in 1752.

Lightning seeks earth ground. Divert lightning to earth before it can strike the church steeple. Well proven by centuries of experience.

Electronics has the same problem. If lightning finds a circuit path to earth via household electronics, then surge damage result. Again well proven is to earth the surge, at service entrance, before surge can enter a building.

It's called 'whole house' surge protectors. But surge protectors are not surge protection. A surge protector is only as effective as its connection to surge protection - earth ground. No short connection to earth ground (which is the problem with plug-in or point of use surge protectors) means no effective connection.

A surge protector is only as effective as its earth ground. Surge protectors are simple science - often hyped into myth. The art of protection is earthing - not a surge protector. Which again demonstrates why 'point of use' protectors are so ineffective. Since they don't provide effective protection, then there is no dedicated (less than 10 foot) connection to earth AND those ineffective protectors avoid all discussion about earthing.

Just as Franklin demonstrated. Surge protection is about earthing a surge. That is what a surge protectors does. Connect all wires to earth ground only during the surge (which is why a surge protector must have a less than 10 foot connection to earth).

The most common source of destructive surges (even to modems) is AC electric. Surge enters on the one utility that typically has no protection. Telephone line has and CATV should have 'whole house' protection. But AC electric - the utility highest on pole and most struck - makes a direct hardwire connection even to modem ICs.

What does a surge seek? Earth ground. Any appliance that makes a connection from AC electric to earth ground becomes a complete surge circuit. Modems and portable phone base stations are easily destroyed. Incoming on AC electric. Outgoing to earth ground on phone line (because telco already installs 'whole house' protector on phone line).

Two minimally sized 'whole house' protectors are sold in Home Depot - Intermatic EG240RC or IG1240RC, and Siemens QSA2020. Never seen any effective surge protectors sold in Sears, Walmart, Lowes, Kmart, Staples, or Office Max. Obviously. They don't have a dedicated connection to earth ground AND avoid all earthing discussions. They don't even claim to protect from the typically destructive type of surge.

Just a few introductory concept about protection. Will not even discuss so many erroneous facts posted in the

FAQ. Discussion for another post. But this is the fundamental fact. A surge protector is only as effective as its earth ground. Surge protectors don't stop, block, or absorb surges. They only shunt - connect all wires together - during the surge. That shunting is protection only if connected less than 10 feet to earth ground.

Halfgaar wrote:

Is it also impossible to protect against indirect hits? I know that direct hits are fatal, but a few days ago, I saw an add in the paper from a company which sells protectors for indirect hits. You don't just buy the device, but also an insurrance. If anything is damaged, they'll pay the damages. Is this possible, or just a trick to get people to buy those things? After all, not everyone who buys such a thing gets hit by lightning (well, their equipment...), so maybe the devices are fake and they just make money on the insurances.

Halfgaar

--
To send email, change nospam.com into yahoo.com.

I have read the faq at penlight. A few more question have come up.

I have this "extensioncord" with, I quote, "full three line surge protection" and "overload protection" and as I said it says "max clamping voltage: 750V with standing surge current 1250A". It has a button which says "press to reset" and a device with an indication light. Is the latter the surge protection and the former the overload protector?

I have an amplifier connected to it which outputs clicks in the speakers when lights and the like are turned off/on. It used to do that before I had the surge protector, and it still does. Isn't it suposed to suppress that? I do have it connected to the ground.

And finally, how can I check if the surgeprotection actually works?

Halfgaar

--
To send email, change nospam.com into yahoo.com.

I am confused as to what that disconnect protector would be. However it appears to disconnect all wires - a relay function. Relays, like circuit breakers, take tens of milliseconds to respond. Well over 400 consecutive and destructive surges could pass through in that forever 10+ milliseconds. Clearly a disconnecting device cannot respond fast enough for the typically destructive surge.

I guess that protector will disconnect UP to 750 volts and up to 1250 amp currents. But a problem. Lighting is current source meaning that it will increase voltage, if necessary, to maintain that fixed flow of current. If something disconnects (or blocks) such surges, then surge voltage increases to overwhelm the isolation. Voltage would increase beyond 750 volts, form a plasma path across the contacts, and maintain that surge current flow.

No way to simple test that a surge protector is working. You could hit it with a surge or conduct the 1 milliamps test. But most people don't have the equipment and knowledge (including component data sheets) to perform that test.

Surge protector have an "OK" lamp. But that lamp can only report if the surge protector is non-functional. It cannot report that the surge protector is good or OK.

The most important component of a surge protection 'system'. What is the quality of earth ground? How to test that surge protection component. Earthing is the art of protection. Basically we install what experience says was a sufficient earth ground or better - then wait (on average once every 8 years) to see if the system works. Repair or enhance an earthing system if anything inside the building was damaged.

Its not all that difficult. Installing a sufficient earth ground is simple. Least expensive if don't when the concrete footing are poured. But rare geological anomalies and other unknown conditions can undermine what would normally be an excellent earth ground 'system'.

Appliances have internal protection. Effects of a nearby strike are really quite small, easily handled by appliance internal protection, and also made redundant by the 'system' designed for direct strike protection. If nearby strikes were so destructive, then all car radios and portable transceivers would also be damaged with every nearby strike.

Another problem is called induced surges. These occur when a direct strike is being earthed. Any wire bundled with that earthing wire would have a transient induced on it. Important that all earthing wires be run separate from other wires to avoid induced surge problems. Many confuse induced surges with electromagnetic fields from a nearby lightning strike.

Induced surge is but another reason why plug-in surge protectors are not effective. They would try to earth the surge down a ground wire bundled with all other wires. Induced transients to other household appliances would result because the surge protector was not connected 'less than 10 feet' to earth ground.

One type of (most interesting) 'disconnecting for protection' device. A radio receiver is placed on the roof listening for radio signals during the formation of a lightning bolt. The receiver sends a message to a disconnect relay in the basement to disconnect phone service AND ground those phone wires. Since lightning formation takes a long time, then the device has time to disconnect AND earth the incoming phone line. This occurs for about 400 milliseconds. Long enough for any incoming surge to be earthed AND not too long to disconnect the incoming phone call. After 400 milliseconds, the phone line is restored; the parties only heard a short conversation interruption.

However the telco provided surge protector basically does same thing at less cost.

Here is the po> I have read the faq at penlight. A few more question have come up.

White pine is said to be an excellent lighting protector. Observations also suggest there is a difference between trees with straight verses circular twisted grain in protection effectiveness.

What affects where lightn> A lightning bolt can carry as much as 30,000 amps. One tenth of an ohm

A lightning bolt can carry as much as 30,000 amps. One tenth of an ohm will drop 3000 volts. What is the resistance to ground of the usual type of lightning rod?

ISTR a guy down at Langmuir Lab being interviewed. He was researching the effectiveness of different types of lightning conductor, all the way from soimple blunt ones to the "sophisticated" types using radioactive sources to ionize the surrounding air. His comments were something on the lines of: "We can't really get meaningful results, because the lightning seems to prefer to strike the trees."

--
Then there's duct tape ... 
              (Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

Reminds them that they're going to have to dig up all that copper and put fiber in sometime soon :-)

--
Then there's duct tape ... 
              (Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

Hi Halfgaar, I think your original question was "Is there a way to reasonably reliably protect electronic equipment from indirect lightning hits". The short answer is yes.

Now for the long answer. Indirect lightning hits induced large currents in metalic objects. This includes but is not limited to telephone and AC mains. I will get into more detail a little later.

Electronic equipment are protected from "Indirect" lightning strikes by using fast acting gas discharge tubes, Sidactors, Metal Oxide Varistors, etc. on the power line and on any interface (such as telephone interface on modems) that could be a source of lethal surges. The function of these devices are to "fire" at a particular voltage (In your case the device inside your surge supressor is rated at 750V) and short the lethal surge either to ground in a 3 wired AC mains circuit or across the circuit it is protecting. Tremendous currents flow in such cases via the device for a very short time (typical for lightning) hence the fairly large value of surge current on your power strip (1250 Amps).

A common misconception is that lightning only hits ground. This is not so. Lightning will hit any object that is "Relatively" lower or higher in potential to the source (the storm cloud in this case). So lightning can strike an AC mains cable too. The AC grid can easily absorb a lightning strike as it designed to withstand and safely discharge such tremendous energy surges. But there is bound to be some surge on the wires before this happens. So lightning could hit your AC mains cables miles from where you live and the currents would travel down the wire into your home and zap all your applicances that are plugged in. This is a case of indirect lightning strike.

Now most power supplies on electronic appliances are designed to withstand voltages much higher than their normal operating voltages for short durations before they burn out. Hence plugging in an appliance to a surge supressor will limit the high voltage spike to a short interval and save your appliance. So the best advice I can give you is to check the specification on your appliance's power supply for it's max voltage and get a spike suppressor will limit the voltage spike to that.

The light and reset switch on your power strip are for the overload protection. This is a reverse protection as you are protecting the AC mains wiring in your home from a shorted appliance or one that draws a larger current than the outlet is rated when it is switched on. Typically devices that have large capacitors or inductors such as motors or high wattage amplifiers with speakers draw a much larger current than normal when switched on. The overload protector saves you the trouble of going down to the basement or wherever to reset the circuit breaker when this happens.

I am not even going into the modem protection as it is not relevant to your original question.

As for how to test that it works? Well that is already done by the manufacturer. One of my duties at my job (I work for a telecom equipment manufacturer) is to zap equipment with an artificial lightning machine to see that it not only withstands an indirect lightning strike safely but also continues to work during that time. There are many standards for equipment surge protection which manufacturers have to meet. (Example K21 for modems)just ensure that when you buy new gear they meet the specs in your country.

As for direct strikes, your only protection is the dude upstairs. Make sure he is happy with you:-)

Also all you dudes who are fans of Ben Franklin style lightning arrestors, get it done by a professional. Remember that such an arrestor will not protect equipment from the indirect surges induced when lightning strikes the arrestor. The equipment has to be designed to have protection or should be connected to the mains or phone outlet via surge arrestors..

Hope this helps.

Vinay a.k.a tube2ic

Your surge protector will not suppress clicks from low amplitude spike in the AC mains due to noisy fluorescents or other loads.

What's the proper name for those glassy tube things that lighning strikes make in sandy soil? I forget.

--
Then there's duct tape ... 
              (Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

Fulgurites.

Cheers!

Chip Shults My robotics, space and CGI web page -

You're saying that the flourescents don't produce a high amplitude spike? But will the surgeprotector probably still protect my equipment from those high amplitude surges?

Halfgaar

--
To send email, change nospam.com into yahoo.com.

Spike from a power line that do not appear with lightning's intensity is noise. Typically so small that surge protectors ignore those transients. Typically so small that internal protection in appliances are more than sufficient.

If suffering frequent power line transients, then you are frequently replacing things far more susceptible to damage such as dimmer switches, cheap radios, and GFCI outlets. Plug-in surge protectors are typically so undersized that frequent transients would degrade a plug-in protector in months. Joules determines how long a protector lasts. Plug-in protectors are typically undersized - often grossly undersized.

Meanwhile, those power line transients would occur too quickly for an electromechanical device, such as that overcurrent protector, to be effective.

Provided previously was one example of why outlet safety ground wire is not effective earth ground - induced transients. Another major reason: wire has impedance. Low wire resistance is why that outlet safety ground is effective for human safety. But wire impedance is why that same outlet safety ground is not an earth ground.

Numbers: that 50 foot of 20 amp wire may measure 0.2 ohms resistance. But same wire might measure 130 ohms impedance to a surge. Suppose an adjacent, plug-in protector is trying to earth a trivial 100 amp surge. 100 amps times 130 ohms means adjacent computer and surge protector would be something less than 13,000 volts relative to earth ground. A surge shunted by adjacent surge protector will seek other destructive paths to earth such as through computer modem.

Now put a surge protector in AC breaker box - a 'whole house' surge protector. Same trivial 100 amp surge would be something less than 400 volts relative to earth. That 50 foot of wire between 'whole house' protector and computer now contributes to computer protection! Protector at wrong end of

50 foot wire could only contributed to adjacent appliance damage.

Bottom line - outlet safety ground is not earth ground because 'a too long' wire has excessive impedance. Because ground wire is bundled with other wires. Because the connection to earth has too many splices and sharp bends. Too many fundamental electrical reasons why outlet safety ground is not earth ground. Too many reasons that say a plug-in surge protector has all but no earth ground. No earth ground means no effective surge protection.

Plug-in protectors avoid all discussion about earthing since effective protection is not even claimed. Why raise an issue that would hurt their grossly excessive profit margin? Currently, many use junk science reasoning - that a surge protector and surge protection are one in the same. Surge protector is simply a shunting device - nothing more. It does not and cannot stop, block, or absorb a surge. Surge protection is earth ground. Surge protector is ineffective without a 'less than 10 foot' connection to the 'system's most critical protection component - single point earth ground.

For reasons of human safety, even ineffective plug-in protectors must meet UL1449 2nd Edition. For reasons of transistor safety, a surge protector must complete a less than

10 foot connection from AC mains to single point earth ground.

Single point earth ground is typically the earth ground rod that breaker box connects. That rod is required by post 1990 NEC requirements. However many older homes don't have an earth ground let alone on necessary for surge protection. Single point earth ground is the point where all incoming utilities connect to the same earth ground rod, ring, plate, or whatever is installed.

Where does a 'whole house' protector connect to AC main. Measure distance from that connection, through surge protector, to single point earth ground. Less than 10 feet. Shorter means even better protection.

BTW, that penlight.org FAQ contained many fundamental technical errors. It was not written by an engineer with technical experience on the subject.

Halfgaar wrote:

Relative to lightning, a fluorescent will not produce a high enough pulse to fire your surge protector. If your fluorescent is ignited using a Ballast and starter instead of the newer electronic ballast, then if your mains is 220V, the ballast produces a surge of about

600-700V to ignite the tube. Once the tube is ignited, the tube itself acts like a regulator and maintains the voltage at around 110V with the ballast dropping the rest. It is the 600-700V spikes produced when your tube ignites that you hear on your stereo. However by the time it reaches your surge protector, the energy is already dissipated and will not be strong enough to fire the suppressor. It should still protect you against a lethal surge such as an indirect hit from lightning.

Now provide the inductance of that choke - the numbers. Ironically, an electronic appliance must already have a superior in-line choke filter. In other threads, some bought cheap power supplies that did not have that required filter. The resulting radio interference was completely unaffected by a surge protector with filter choke - because that surge protector filter choke is simply too small.

Surge protectors do not stop, block, or absorb surges. They are called shunt mode devices for good reason. Their job is to simply shunt (connect, distribute, short) a surge from one wire to all others. No short, dedicated, and independent connection to earth ground means the plug-in surge protector only provides a destructive surge with more paths to find earth ground - destructively through adjacent appliances.

A good quality surge supressor notes the critical importance of earthing. Benchmarks in surge protection, such as Polyphaser, don't discuss their product line in application notes. Polyphaser discusses the most critical component in any surge protection 'system' - central earth ground:

How important is earthing to Polyphaser? A product does not even have a connection to earth ground. Distance to earth must be so short that the Polyphaser product mounts directly ON earth ground. But then those who know surge protector know that Polyphaser is an industry benchmark. Therefore Polyphaser discusses earthing - extensively.

No earth ground means no effective surge protecti> A good quality surge supressor, would have at least one common mode

This is complicated matter. A short answer please :): Does a point of use surgeprotector has any use when you connect it to the safety ground (as the one I have is designed to)?

And you say that with many power transients, the protector breaks down fast. But in the penlight faq, it says that surges happen all the time. If the protector nullifies all the surges, then it must be dead very soon, right? And if it is a shunting device, shoudn't I notice power cutt-offs all the time?

Something else I thought of: Some devices say something about FCC rules, that it doesn't create harmfull interference and that it must accept any harmfull interference received. I'm not sure if this is just for radio equipment. Is it? Or does it have anything to do with surges?

Halfgaar

--
To send email, change nospam.com into yahoo.com.

I'll check the parts sometime.

Won't measuring the phase and the ground create a leakage so that the "earth leakage breaker" (I don't know what it's called in English) will disconnect power?

Halfgaar

--
To send email, change nospam.com into yahoo.com.

To be earth grounded, that surge protector must make a less than ten foot connection from incoming utility wire to earth ground. Surge protector is a switch - that closes only during the surge. During a surge, the protector must make a less than ten foot connection from the utility wire to earth ground. But, again, wire impedance means a fifty plus foot wire connection to earth ground is all but no earth ground. That ten foot is essential to minimize impedance. Not only short - less than ten feet. Other requirements. The connection must have no sharp bends, no splices, not inside metallic conduit, not bundled with other non-grounding wires, etc. This is explained in greater detail in the newsgroup misc.rural in two threads among engineers: Storm and Lightning damage in the country 28 Jul 2002 Lightning Nightmares!! 10 Aug 2002

or

Outlet safety ground typically is not earth ground - from the perspective of a surge. Wire is too long - and other problems.

A plug-in surge protector may be effective if plugged into the receptacle attached to breaker box and if the protector power cord is cut short. Then it might make the less than 10 foot connection.

As noted previously, that penlight.org FAQ has many gross errors. First one I remember was that nonsense about many daily surges. First, if you are suffering daily surges, then you visiting your local hardware store to replace dimmer switches, electronic timer switches, touch on-off lamps, GFCI human protection electronics, etc.

If you are suffering such daily surges, your utility must be confronted. But then if you are suffering such surges, the same 'whole house' protector is properly located and properly sized to also address those problems.

Even a computer power supply is an RF transmitter. It typically transmits a 20 Khz voltage through a smaller transformer. All electronics must not radiate radio frequencies. Power supplies, for example, (are suppose to) have in-line filters to keep noise from interfering with AM radios. That inline filter also is part of the power supply's ability to withstand surges.

UL is concerned only with human safety. NEC is about human safety. FCC is concerned with radio frequency interference and communication standard. None make standards for surge protection. However some things they require are also provide surge protection.

Don't waste big bucks on typically undersized 'point of use' (plug-in) surge protectors. Money is often better spend improving, enhancing, or creating a single point earth ground. Then have all incoming utilities connect less than 10 feet to this earth ground - either by direct hardwire connection (CATV, Satellite dish) or via a surge protector (AC electric, telephone). The most critical component of a surge protection system is earth ground. Surge protectors are simple components, sometimes required (sometimes not), to make the earth ground surge protection system effective.

Halfgaar wrote: