surge protectors

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Joshua Putnam wrote:

Generally all protectors attentuate signals. In earlier days, I always wondered why center core connection was not performed. Some experienced professionals in the rec.radio.amateur.antenna newsgroup confirmed what I had been told. Leakage from the center conductor to a well earthed outer conductor provides sufficient protection. A capacitive protector on center core would only attentuate signals; provide little protection advantage. But then some legendary manufacturers do make protectors that include that center core.
You are not earthing a 200,000 amp direct strike - which you probably will never see in your lifetime. Using a ground block to earth the outer braid is a massive protection improvement. If you still need better, then visit some expensive and superior protector manufacturers such as www.polyphaser.com .
Nothing 'stops transients on the ... conductor'. Anything that stops or blocks such transients is not effective. Effective protection is diverting. Destructive transients seek earth. Therefore the sooner that transient is diverted / earthed (meaning a shorter connection to earth and farther from transistors), then the better that protection.
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w_tom wrote:

Tom like to make an argument out of everything, including symantics. Most reasonable folks would agree that if a protective device shunts a surge to ground, that it has in fact stopped the transient, because the destructive transient does not make it to the protected equipment.
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snipped-for-privacy@optonline.net wrote:

Granted it is a minor point. But the point is made because many assume a plug-in protectors sitting between a transistor and a surge will somehow stop or block what three miles of sky could not. Effective protectors 'shunt'. Those protectors that don't have earth ground hope one assumes it will instead 'stop' or 'absorb' a surge to promote a myth. Even shunt mode plug-in protectors only shunt - divert - a transient. To be effective, it must shunt to earth and not divert into the appliance. A 'semantic' that can otherwise create confusion - promote an ineffective product.
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This is the only place I dissagree with W-Tom. He is 100% right about the importance of a single point ground, bonding of all point of entry protection plus the importance of solid grounding electrodes and connections. You should try to stop the surge at the service entrance but where I dissagree is I still think a plug in protector has value to catch the things his point of entry system didn't stop. These will usually be a very low order tranient if the POE system was working but still enough to hurt you. It is better to heat up a shunt wired MOV than to let this into a MOSFET. Good point of use protectors also have a large ferro resonant componant that will eat some heat too. It still needs a good ground path back to your grounding electrode system, just to stabilize the reference levels. He is right that it does little good to clamp the transient if the resulting "zero" is 40v above the ground reference of the interface lines. You can't have too many layers of protection if you live in a lightning area. I just like to add another layer to his system. When I was doing physical planning for a large corporation that sold business machines internationally we had a lot of lightning experience is South Florrida. Layers of protection works for people who can't turn off their system and unplug it every afternoon in the summer.
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snipped-for-privacy@aol.com wrote:

I agree. Tom starts off with good advice, but then goes down the path of "If the whole house surge protection didn't work, then you did something wrong and point of use protectors are useless." I and many others have had experiences where it was pretty clear that plug-in surge protectors did work. He's right, that a short ground path with a service protector is clearly better, but that doesn't mean the plug-in protectors are totally useless. A lot, for example, depends on the rise time of the surge. The slower the rise time, the less impedance there will be.
Also, for many folks, eg, those living in apartments, a whole house AC protector is just not possible.
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w_tom wrote:

The cable shield was grounded via a grounding block, a 4' piece of #10 bare copper wire, and a separate grounding rod of unknown length, all installed by the cable company. They have since rerouted the ground to the service entrance ground.

The modem was damaged from the incoming phone line. The computer was switched off. The modem's impedance matching transformers were blown along with the input/output stage. By the way, the phone line is all underground for miles so it was a ground induced surge. But that is not uncommon.
Bob
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Bob wrote:

Plug-in surge suppressors for cable TV need to have a port to include both the power and cable TV. The multi-port surge suppressor will clamp all voltages on power and signal wires to the common ground at the suppressor. The IEEE guide at http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf explains this quite well. It says the cable center conductor can be 4000 volts with respect to the shield. A plug-in suppressor will clamp this, likely with a gas discharge tube. A bigger problem is if the cable entrance ground block is not near, and connected with a short wire, to the power service earthing conductor. That is also protected by a multi-port plug-in surge suppressor and is illustrated in the IEEE guide.
Similarly, a plug-in suppressor for a computer with phone connection has to have ports for both power and phone line.
bud--
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Plug-in protector has no effective earth ground. No earth ground means no effective protection. Therefore Bud's article shows a plug-in protector putting two TVs at 8000 volts. Will those TVs at 8000 volts not be damaged - not leak currents in destructive paths? No. Those TVs may be damaged because they are at 8000 volts. Bud's citation even demonstrates why plug-in protectors can contribute to damage.
Other papers he forgets to cite note how plug-in protectors can even contribute to damage of that adjacent appliance - TVs: Martzloff and Key in 1994 wrote in "Surging the Upside-Down House: Looking into Upsetting Reference Voltages" :

But then that is what the mikeholt.com paper also demonstrates on page 33/34 in figures 8 and 9. TVs put at 8000 volts because a plug-in protector is too far from earth ground; therefore is not properly earthed. Earthing is essential to effective protection.
The paper on page 22 says:

Of course. A protector is only as effective as its earth ground. That protector adjacent to TVs put those TVs at 8000 volts - ineffective protection. Effective protection must make a low impedance connection to a good earth ground. That again means a protector located 'less than 10 feet' from earth. Even Bud's paper demonstrates how "objectionable ... voltages ... occur even when or perhaps because surge protective devices are present at the point of connection of appliances". The adjacent protector can even contribute to damage of electronics. .
Bud-- wrote:

http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf
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w_tom wrote:

The IEEE guide clearly describes the action of a multi-port plug-in surge suppressor as clamping all wires to the common ground at the surge suppressor, with earthing being secondary. Why does chapter 6 of the IEEE guide "SPECIFIC PROTECTION EXAMPLES" use multi-port plug-in surge suppressors in both examples??
I agree with <wfretwell>. that a service panel surge suppressor and a single point ground are both a very good ideas. The question is whether plug-in surge suppressors are effective. To anyone who can read, the IEEE and NIST guides clearly say they are.
You have proviced no reputable links saying plug-in surge suppressors are not effective. Where are your supporting links??
bud--
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I had a surge once (caused by nearby lightning strike) while I had 3 five outlet strips connected together in one room. The surge protectors were destroyed and the carpet they were sitting on was scorched/burned but nothing that was connected to them was damaged which included a computer a police scanner , shortwave radio and a couple of other small items. During the same incident in an adjacent room another surge protector was destroyed along with a VCR but a TV that was connected to the same protector was spared. RM~
PS, The surge protectors in use had well constructed metal housings. I suspect we would have had a fire if they were of the plastic type.
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Rob Mills wrote:

I had a similar experience, where my PC and Fax machine, which were connected to the strip type surge protectors including phone line protection were undamaged. During the same event my Tivo, which did not have a surge protector on the phone line, had the telephone/modem interface blown out. Of course, Tom has told me that this happened by the surge coming in the AC line, getting through the AC surge protector, going through the Tivo, and then blowing the modem on the way out the phone line. I think the rest of us have a pretty good idea of how it happened.
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snipped-for-privacy@optonline.net wrote:

I do not have lighting surges so I am pretty lucky.
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For "have a pretty good idea of how it happened", than what also protected those other undamaged electronic appliances? What protected those kitchen and bathroom GFCIs? What protected the smoke detector? What protected the dishwasher? How did those appliances without plug-in protectors not suffer damage? Invisible surge protectors?
You are using same logic process that somehow proved childhood leukemia from AC electric wires. Selectively ignoring other data such as that undamaged microwave oven and furnace controls. Meanwhile, demonstrated was how a plug-in protector simply provided lightning with a destructive path through a network of computers. Shunt mode protectors require earthing. No earth ground asks how does that surge get shunted into earth? Via adjacent appliance. Or maybe another appliance acts as a surge protector - shunts the surge to earth destructively. IOW you only assume that protection works and completely ignore that air conditioner control electronics that was not damaged.
A method of making a kludge 'whole house' protector for apartment dwellers was defined. Take a plug-in protector of maximum joules. Cut its six foot power cord down to near zero feet. Plug it into the wall receptacle that is closest to earth ground (and breaker box). It becomes a 'poor mans' whole house protector. Best you can do if an apartment owner will not install your 'whole house' protector.
But again, what makes that kludge solution into better protection? Shorter power cord. Closer to earth ground. Increased distance from appliance to be protected. What does a shunt mode protector do? It shunts. Either it shunts a transient into earth (safely), or it shunts a transient to earth, destructively, via the adjacent appliance. Or it does nothing because the Tivo did that shunting.
Meanwhile: "getting through the AC surge protector" ? Do you think some magical blocking device exists inside a shunt mode protector? Incoming protector wire and outgoing receptacles are direct electrical connections. Nothing 'blocks' inside that protector. Wall receptacle connects directly to appliance plugged into that protector - a direct wire connection. In fact, if a protector provides protection to its receptacles, then protector also provides protection to anything plugged into other side of same duplex wall receptacle and to other wall receptacles on same circuit.
Nothing inside a shunt mode protector stops or blocks surges. Protection is about diverting surges before surges gets to the appliance. Protector is designed with transients "getting through the AC surge protector". That direct connection is what wire inside the protector does.
snipped-for-privacy@optonline.net wrote:

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w_tom wrote:

Last time I checked, none of the devices on your list above gets connected to the telephone line. The PC, FAX, and Tivo were connected to the telephone line. The PC and FAX were connected through a strip type surge protector and survived a surge caused by a thunderstorm. The Tivo was not connected The Tivo had the modem section blown out, while the rest of the Tivo was still functional.
Based on that, it seems very reasonable to conclude that the surge likely came in on the phone line and that the surge protector for the PC and Fax very likely saved them. However I know you will argue otherwise.

Again, the furnace and microwave were not connected to the phone line.
Meanwhile,

Hmmm, is your air conditioner connected to the phone line?

Rant on Tom. Others have provided links to credible sources, like the IEEE, that clearly state that plug in surge protectors can be effective and part of a tiered protection system. They even clearly show a diagram in chapter 6 of exactly the settup that saved my PC and FAX, while the unprotected Tivo got whacked. Now, who should we believe, you or the IEEE?
happened.
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snipped-for-privacy@optonline.net wrote:

So how did a surge enter on phone line, ignore the telephone line 'whole house' protector, destroy Tivo ... and then stop? What kind of electricity does trader4 have that crashed on a Tivo like a wave on the beach? That can decide to ignore a phone line protector but is somehow miraculously stopped by a plug-in protector.
Trader4 knows how damaged happened only because he had damage and then made assumptions. It must have been incoming on phone line because only Tivo was damaged. What about other phones? What about portable phone base station? He has no other phones - or just forgets to mention that they too have no surge protector and yet were not damaged.
A warning about how phone line items (Tivo. portable phone base stations, modems, etc) are easily damaged when a 'whole house' AC electric protector is not installed. Incoming on AC electric (that has no protection) AND outgoing to earth via phone line is typically how phone appliances are damaged. Phone line already has a 'whole house' protector provided free by the telco. But somehow trader4 suffered Tivo damage from a surge protected phone line. Somehow his surges ignore earthed surge protectors - of they really enter on AC electric that has no 'whole house' protector.
Somehow AC electric that even protects phone lines from lightning, that is more often struck, then enters without any earthed protector, and connects to most every household appliance including Tivo - somehow AC electric did have any surge? Somehow lightning never struck AC electric AND somehow a surge completely ignored the telephone line protector? In reality, surge was on AC electric and other appliances protected themselves. Lightning strikes AC electric wires - the most exposed - most often. AC electric is the most common source of damage even to phone line appliances. And then there is the telephone line protector that somehow a surge will completely ignore to damage Tivo. He must have treacherously smart surges.
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