lightning protection

No. A voltmeter is high impedance. If you use a lamp then it would probably trip. (Depends on your system)

That's the one! Thanks.

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nofr@sbhevre.pbzchyvax.pb.hx

I still don't know what your 750 volt 1250 amp device is. But we know it is not an effective surge protector. Posted previously on 26 Jul:

If it does not have the less than 10 foot earth ground connection OR it does not even discuss earthing, then it probably provides no such protection. Identifying ineffective protectors is that simple. Furthermore implied, it is an electromechanical device. Again, cannot protect from hardware destruction. Too slow. Remember the microsecond destruction followed eons later by the millisecond response of that device?

It might be doing something else. But it is not protecting electronics from potentially destructive transients. Conditions repeated in that first paragraph make it obvious what the device cannot do.

In the meantime, where are contradictory responses. Only one provided blunt technical facts that say that device provides no transient protection AND could not do so. Facts with numbers such as microsecond destructive transients that cannot be stopped by a millisecond responding device.

First provide some specific claims, with technical numbers, that says what the device does. Currently, we d> I seem to be getting several conflicting answers here.

Surges are ideal current sources; not voltage sources. Incoming surge will increase voltage as necessary to get to the appliance or earth ground. But surge protection is about making a lower voltage connection to earth. Less voltage (because current is shunted to earth on a low impedance connection) means a surge (now at less voltage) will not seek alternative destructive paths through appliances. But too much impedance to earth ground (such as through wall receptacle outlets) means the surge must find destructive paths via adjacent appliances. This is basic circuit theory.

Knowledge of basic circuit theory would have made that obvious. Bottom line, surge protection is about earthing a surge before it can enter the building. Once inside the building, destructive current flows can be everywhere. Far too complex to justify the analysis or to be solved with simple plug-in solutions. Best to earth a surge at the service entrance and be done with it - at far less expense.

Misrepresented is the cost of 'whole house' protection. A plug-in protector for only one appliance may cost $15 or $50 per appliance. The 'whole house' protector costs maybe $1 per protected appliance. The so low cost of effective 'whole house' protectors that makes 'whole house' protection a good investment for the event that typically occurs once every eight years.

Why does the telco install 'whole house' protector on your premise interface? Because and again, the 'whole house' protector is so inexpensive, so effective, and not a grossly overpriced $25 for one appliance. Telcos don't waste money because they are big companies. The smart money also installs a 'whole house' protector on AC electric for that $800 computer and the other 100 other household appliances. What protects that furnace, dishwasher, dimmer switch, and bathroom GFCI for human safety? No plug-in surge protector even claims to provide that protection.

I suspect you are totally lost on too much information and not enough technical background, as indicated by recommending sources such as PG&E. Where are the technical numbers at PG&E (a company so short of technical competence that its President was a lawyer who did not even understand why future markets are essential to utilities). I tried to keep it simple. Provided was only enough to introduce concepts - why 'whole house' protectors are so effective and why plug-in protectors are not sufficient (as well as grossly overpriced). Provided was information from application notes for further study. But if you think that anything posted was learned solely from application notes? Probability says I have been building and experimenting with surge protectors before most here even existed. To tell me that the plug-in surge protector is effective without comprehension even of basic circuit theory is rather discourteous.

The more expensive and least effective surge protector solution is that $25 plug-in protector. It does not even claim protection that so many wish it to provide. Of course not. It must avoid this quote that should sound familiar:

Halgaar, It is unfortunately the nature of a newsgroup to give you anything but a definite answer. I strongly urge you to read this brochure for the layman by National Institute of Standards and Technology (US Dept of Commerce).

You should also look at the website of your local utility company for information. These are un-biased independent bodies which tell it plain vanilla.

To give credit to Tom, he is not telling anything that conflicts too much with what I am saying. It is the details that are off and can mislead a layman. The facts that he quotes from application notes are obviously correct. The only thing that he doesn't get is that surge protectors are classifed into grades, classes and work in different modes, based on their design, scale, type of protection. What he is talking about are service panel surge protectors for whole house or even a metering-panel protector that is installed by utility companies in areas of strong lightning activity. What you are asking about are called plug-in surge protectors. They do work if they are properly designed. Unfortunately with the information you have provided, there is no way to tell if yours is properly designed. Should you leave it out? Maybe not because even if it does half of what it's supposed to do, it's still better than nothing. But is it guaranteed to work? Hard to say. You have to be aware of the risks.

Also it is always dangerous to have independent earth grounds due to a phenomenon called ground bounce. All grounds have to be tied to a common point to earth ground using special very thick bonding conductors that are low impedance which nullify all the effects he keeps talking about. (Little knowledge is a dangerous thing). Do you seriously imagine that Utilities, Telcos and Government agencies do not give any though about these things? There is a regulation/standard for everything.

Thirdly all lightning rods are not created equal. There are types which are proven to be ineffective. As a layman you cannot rely on the say so of a manufacturer. You need to look for unbiased information from organizations such as the National Lightning Safety Institue

We need to keep things in perspective. To protect multi-million dollars of equipment, you need to spend hundreds of thousands of dollars in surge protection. To protect a thousand dollar appliance you need to spend a hundred or less. Is the hundreds of thousand dollar protector better than the hundred dollar one? You bet your life it is. So are you going to go buy the former? A fine fool you will look if an indirect lightning stike destroyed your thousand dollar protector in saving your 300 dollar TV.

Lastly, lightning as a phenomenon is still not understood fully. There are several groups of researchers that are at loggerheads with each other. So until there is agreement by the experts, there will always be conflicting opinions.

Hope this helps. I will not post further to this list as I have a new project. I have to design lightning protection for some mobile wireless equipment that will keep me in the lab zapping equipment for several weeks. Ta Ta Halfgaar all the best in your quest.

Depends where you live:

"Ground fault current interrupter" (GFCI) in North America.

"Earth leakage circuit breaker" (ELCB), now obsoleted by "Residual current circuit breaker" (RCCB), or "Residual current device" (RCD), in the UK.

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I don't really know what it's supposed to do. It was written on the box, at least in some stupid metafor, but I don't have the box anymore.

And about the 10 ft, Tube2ic doesn't seem to think it's all that important.

I think I know all I can find out here. I'll do some more research and hopefully find out some more.

Thanks to all for your time.

Halfgaar

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I don't know about your particular case, but I tend to view these as paying for the insurance not surge protection. Given that most power in UK cities comes in underground I am extremely dubious about the value of these devices in my enviroment. I would rather pay for better quality plugs, sockets and cable.

I have seen one of these fail to protect its load, turned out the "electrician" had wired up between the red & blue busbars (across

2 phases of a 3 phase line) and stuck 400V at practically unlimited current up an alegedly 240V feed. The smoke was impressive.

Regards, Dan.

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One must display knowledge of basic concepts such as impedance, common mode transients, and etc to make a credible claim about surge protection. Another does not yet demonstrate knowledge of basic circuit theory or wire impedance. That knowledge is necessary to understand the critical - absolutely essential - nature ofthat 10 foot connection. How can one demonstrate no underlying knowledge and yet be treated with equal credibility? Did he post any of these previously posted facts: the relationship between joules and MOV life expectancy, other factors that adversely increase wire impedance, underlying principle of single point earth ground (with examples from industry professionals), purpose of UL, NEC, FCC and other standards, timing relationships between response times and surge transients, how to test that a MOV is still effective, myth of destructive surges from fluorescent lamps, 'OK' lamp nonsense and what it really reports, relationship between surge protector and surge protection, frequency of destructive transients, effective protection has been proven everywhere since the

1930s meaning that surge damage is directly traceable to human failure, other protection devices including some species of trees, appliances have internal protection (with numerical examples), difference between a destructive surge and trivial noise, long list of reasons why we know household appliances don't generate destructive surges, receptacle safety ground is a different and not earth ground, human safety verse transistor safety, that all so critical single point earth ground, post 1990 NEC changes that may provide a minimally acceptable central earth ground, underlying geology can affect surge protection, numerous outright errors in the penlight.org FAQ, power supplies are RF transmitters that require AC mains filtering (which surge protectors can't provide), how some utilities don't even need (nor should use) surge protectors to provide effective surge protection, telco phone line already has effective protection, that chokes, inductors, and filters are equivalent, what that filter really does inside a surge protector, wire impedance is so critical that even Littelfuse worries about wire impedance on an MOV's 2 inch lead, Polyphaser and their application notes, $15 to $50 per appliance for ineffective protection verse $1 per appliance for effective protection, and even how this all ties in direct with Ben Franklin's original 1752 experiments.

Posted were examples *with numbers* as to how wire impedance makes plug-in protectors ineffective. How many numbers did another provide to prove that 10 feet is not relevant? No numbers is akin to promoting junk science. But to provide those numbers, knowledge of impedance calculations is necessary.

Another says only "I don't agree" and suddenly has has equal credibility? If he said Saddam was going to launch weapons of mass destruction in the next 45 minutes, would you believe him? At what point did you stop seeing the difference between technical fact and an ill informed reply based only upon personal feelings and insufficient technical background?

You have a fact to take to your grave. If that protector does not make a dedicated connection OR avoids all discussion about earthing, then it is probably ineffective. Ineffective protectors are that easily identified. A surge protector is only as effective as its earth ground.

A surge protector is only as effective as its earth ground. That plug-in device has no earth ground for a long list of reasons summarized above. At this point you should know exactly what 'no earth ground' "is and means" to your mystery device.

Halfgaar wrote:

I'm Halfgaar, I believe you got me mixed up with Tube2c.

Granted, It's very hard to dismiss what you're saying, seeing as how you explain everything in detail. But as I said, I think I've found out everything I can here. I'll just keep in mind what you've said when for example asking about it in specialist-electronicshops (not the household electronics shops, they don't know anything).

Also what worries me, is that if you're right, then there is no (inexpensive) way to protect against surges and that plugin protectors are (almost) all just junk. There will be a lot of people who feel safe but actually are not.

Halfgaar

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Where I come from, all cables are underground as well, but what about surges from electronics and welding machines nearby?

Well, continuous 400V is not exactly a surge. A surge is usually hunders of volts, as I understand it.

Halfgaar

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Hi Halfgaar,

Don't waste your breath on this guy. At first I thought he was genuinely trying to help you and had just got a few facts mixed up. But a quick search on google groups for w_tom soon convinced me this guy is a crock. He even got told off by some ladies at alt.sewing for some drivel about unplugging their sewing machines during a storm and the same drivel about whole house protectors and 10 ft grounds. To cut a long story short, I think that this guy got his brains zapped in due to lightning. Probably because he forgot to ground himself by sticking a 10ft grounding rod up his backside.

It is not my nature to be offensive to anyone but this guy w_tom is the limit. He is the epitome of everything that is bad about the internet and newsgroups. Unreliable information that sounds just about right to convince a layman while having no accountability for his actions coupled with sheer volume of rubbish text and complete disregard for the relevance of his drivel to the thread. I have yet to see him actually answer a question!

-Tube2ic-

From my point of view, you could easily be the one telling lies :). But fear not, my gut already told me to trust you more then him.

BTW, just to let you know: The voltage over phase and neutral is 226 here. The voltage over phase and ground is 226. That falls within the 2 volt limit, wouldn't you agree :)?

Anyway, thanks for the warning.

Halfgaar

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Granted they do not help with surge protection, but in terms of increased system reliability for a given amount of investment the case is not anything like so clear.

Regards, Dan.

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Yes! Unfortunately that is the way of the newsgroup :-)

You have a smart gut there Halfgaar feed him a beer from me:-)

Yes that is fine. In many countries the neutral is actually tied to ground at a particular tie point and so there would be no difference in voltages unless you are very far from that tie point between neutral and ground. The tie point could be the transformer, the pole or your utility meter, depending on the regulation for your country. This is the reason I said a two-pin surge protector is also possible provided that it was originally designed for two-pin operation.

------------------------------------ Another common problem that could cause damage to electronic equipment and cause protection mechanisms to work incorrectly is the transposing of phase and neutral at the socket. I don't know what is the standard in your country but you should spend a few minutes checking this. Typically the molded plugs on some appliances display this and that may be a good starting point to verify. If a surge protector was designed with only one shunt element between phase and ground then plugging in such a protector into a transposed socket would actually put the shunt element between neutral and ground which is at the same potential and therefore would be no protection at all. Better quality protectors have two shunt elements between each line to ground pin.

-tube2ic

In case of indirect lightning strikes, it does not matter whether the cable is underground. The energy is still picked up by induction.

The shunt element in the protector is designed to fire at anywhere between 260 to 700 volts depending on the design. It is also not capable of contiuously shunting energy when fired. Hence a good protector should have a series fast acting fuse which will blow as soon as the shunt element fires and shorts out the AC mains. Otherwise the protector will be destroyed. (Note that the fuse is really not much help for lightning protection and it's purpose is to protect the protector in similar situations as above e.g. if a high voltage line fell on a utility mains wire) Halfgaar you mentioned about the overload breaker on your protector. If the overload breaker is wired before the surge supressor, then it will also perform a similar function as described above. If the overload breaker is behind the surge supressor then its primary function will be what I already described earlier.

A surge is any voltage above normal. when a surge lasts for a longer duration, it may sometimes be called a swell. However, your case was that of incorrect wiring and not really a surge on a normal line.

Well, to find that out, I have to open it up. It at least is psysicly closest to the powerinlet, so I would guess the power goes trough that one first.

Halfgaar

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I would not assume that. It is a simple matter to open it and check. That way you will be absolutely certain.

The typical devices used as shunting element are voltage sensitive. This means that at normal voltage they are very high impedance (Open circuit). When a surge reaches the voltage at which the device activates, the device goes into low impedance state (short circuit). As soon as the voltage drops to normal, the device stops conducting and goes back into open circuit state. This clamps the voltage at the firing voltage of the device during a fault condition. Now if there is a fuse or breaker and the surge is long enough in duration, the shunt element (which is actually shorting your AC mains) will cause enough current to flow that will cause the fuse to blow or breaker to trip and thus interrupt the supply and protect the shunt element. If the surge is short duration, the short is momentary and does not blow the fuse or trip the breaker. (This is because a fuse or breaker responds relatively slowly to the fault condition) so all that will happen is that the voltage clamps to the firing voltage of the shunt element. (And you will hear horrible farts in your stereo system :-) Sometimes people replace the fuse with one of a wrong rating or response time (Or there isn't a fuse) and this results in spectacular fireworks as the shunt device is destroyed due to the high currents flowing through it.

I also found a website that explains surge protectors in fairly simple terms (No numbers to satiate our friend w_tom :-) but should do well for you)

The explanation is fairly simplistic in that it assumes a number of things but it give a good enough picture of what goes on inside the protector.

-tube2ic-

In the previous post, where I describe the destruction of the shunt element due to wrong or no fuse, I want to clarify that this happens for the longer duration surges that allow enough current to flow that is lethal to the shunt element.