surge protectors

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 dem> An effective, low-impedance ground path is critical for the

Of course. A protector is > Plug-in surge suppressors for cable TV need to have a port to include

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explains this quite well. It says the cable center conductor can be 4000

Reply to
w_tom
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You don't understand wire impedance. You insist that industry professional papers are lies. Those burning power strip protectors due to failing MOVs somehow are not fire threats? Meanwhile others who want effective protection learn why properly earthed and properly sized 'whole house' protectors from responsible manufacturers such as Square D, GE, Siemens, Polyphaser, Cuter-Hammer, Intermatic, and Leviton make that short connection to earth; therefore provide effective protection.

Reasons why such protectors sold in Home Depot and Lowes are long; assume the reader understands basic electrical concepts such as wire impedance. To make such problems such as wire impedance irrelevant, we install an effective protector with a 'less than 10 foot' connection to earth. Apparently concepts such as wire impedance and MOVs vaporizing is completely new information to Pete C. Others are encouraged to learn why above manufacturers of 'whole house' protectors are considered so responsible; provide effective protection. In the case of Polyphaser, that protection is considered legendary.

Reply to
w_tom

I understand wire impedance, you apparently do not and misapply the concept. You haven't provided reference to any industry papers that support your assertions.

Failing MOVs in an old poorly designed power strip / surge suppresser combo that doesn't meet current standards could well be a fire threat, however they have not been "vaporized" by a surge as you have claimed.

I have effective protection and it's multi level distributed protection as good engineering practice dictates.

It starts with a Square D suppresser on the Square D QO series panel, Leviton coax suppressers adjacent to the ground blocks at the CATV demarc, the integral suppressers in the telco demarc and solid heavy gauge ground leads to the adjacent 8' grounding electrode which is solidly bonded to the secondary 8' electrode about 10' away.

It does not however end at this point in a "hope for the best" strategy, the protection continues further with reasonable quality suppresser / power strips (that have status indicators and thermal fuses), a large quality UPS on the server rack, and additional suppressers on internal phone / data / CATV lines.

Apparently folks like you latch onto technical terms like "wire impedance" without bothering to get an understanding of what it really means and how it is not the same as the wires DC resistance. You have also not provided a single link to your claimed "vaporizing" MOVs.

The answer to the OP's original question "It is dangerous to have more than one surge protectors in you home I have 3 surge protectors running in my home." is clearly "no", it is not dangerous.

And as myself and others have indicated a quality "whole house" suppresser is very beneficial, but it does not obsolete secondary suppressers further down the line, nor does it obsolete suppressers on non power lines like CATV, phone and data.

Pete C.

Reply to
Pete C.

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.

Reply to
trader4

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.

Reply to
trader4

I do not have lighting surges so I am pretty lucky.

Reply to
karsan

They are all called shunt mode protectors. Typically destructive transient seeks earth ground. Each layer of protection is defined by its single point earthing. Primary protection is provided by a utility and requires homeowner inspection:

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Secondary protection is the 'whole house' protector, et al - also defined by its single point earth ground as demonstrated by:
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In each case, wire impedance must be kept low as repeatedly cited in professional papers - which means short distance, no sharp bends, no splices, not inside metallic conduit, etc.

When Orange County FL emergency response system suffered damage from lightning, then reasons for system protector failure were repaired. They fixed the earthing system:

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Why? Each protector is defined by what it connects to. Earth ground. Those interior protectors claim to protect from what type of surge? Well plug-in protectors don't even define protection for each type of transient. Why let a consumer know it protects only from a transient that is typically not destructive and that is made irrelevant by protection already inside equipment.

Many plug-in protectors are undersized because that MOV vaporization even promotes protectors to the naive. Meanwhile, if better protection is required, did Orange County install plug-in protectors? Of course not. They enhanced earth so that effective protectors would perform even better.

What does that protector inside a plug-in UPS do? Where in numerical specs does it even claim protection? Is dBs filtering considered protection? No. Do standard numbers such as C62.xx or UL1449 define protection? No. It does not list protection from every type of transient because you might notice a glaring anomaly. With no low impedance connection to earth ground, it does not claim to protection from surges that cause damage. They forget to define protection from each type of transient so that a consumer might assume it. And then we have this layer of protection - forgetting to mention what defines each layer: earth ground.

Pete C. has a problem with low impedance wiring requirement when virtually every responsible installation requires 'a low impedance connection'. His own Square D 'whole house' protector is reported earthed by 10 feet. Of course that protector could be made better if earthing wire was shorter, no sharp bends, separated from other wires, etc. Each protector is defined by quality of and connection to its single point earth ground. As one industry professional defined it for every building owner and operator:

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The keys to effective lightning protection are surprisingly simple, and

They are called shunt mode protectors. They don't magically stop surges. As wire impedance increases, then surges find other (destructive) paths to earth. Wire impedance defined by an equation where wire impedance increases proportional to wire length multiplied by a factor that includes the Log of 4 times wire length divided by wire diameter. Wire length increases wire impedance twice over which is why low impedance means a shorter connection. A fact demonstrated as relevant by Thottappillil in "Electromagnetic Pulse Environment of Cloud to Ground Lightning for EMC Studies":

Of course, higher impedance means higher maximum overvoltage when we want voltage to earth to be as low as possible. So we carefully lower that wire impedance connection to earth.

As wire gets longer, impedance increases unacceptably. Polyphaser notes in TD1023: Multiple I/O port protection, Single Point Ground considerations at:

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Another complication in this scenario is the inductance of the

So what does that plug-in protector adjacent to two TVs do? Leaves both TVs at 8000 volts. Why? Wire impedance to earth ground is too large causing TVs to sit at 8000 volts during a surge. Where is the protection? Demonstrates how a plug-in protector - without a low impedance connection to earth - does nothing useful.

Some hype a myth about layered protection and forget to mention what defines that layer - earth ground. Why would supplemental protectors with excessively high impedance somehow earth to a point that the surge ignored when entering a building? If that earthing was made superior, then a surge is better earthed by the 'whole house' protector. And if earthing is not sufficient, then why is a supplemental (plug-in) protector going to earth to that same insufficient earth ground?

Rather than waste money on plug-in protectors, what did they do in Orange County FL? They repaired reasons for lightning damage - insufficient earthing. Plug-in protectors are in the same protection layer as a 'whole house' protector. If 'whole house' protector's earthing is not sufficient, then a plug-in protector - with excessive wire impedance - will somehow earth to same ground? Nonsense. And yet that is what plug-in shunt mode protectors must do.

BTW, another solution called series mode protectors; beyond scope of this post.

As has been repeatedly demonstrated, even in a paper from Martzloff, et al:

Each layer of protection is defined by the and most essential system component - earth ground. Primary protection layer is earthed at the utility pole. Secondary protection layer is properly earthed adjacent to 'whole house' protector. Since plug-in protectors don't even claim such protection in numerical specs, then such protectors neither have a dedicated wire for earthing nor do they even discuss earthing. A shunt mode protector earths. No earth ground - such as with plug-in protectors - means no effective protection. Better is to put money into enhancing the earthing system.

Lower wire impedance c> I understand wire impedance, you apparently do not and misapply the

Reply to
w_tom

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.

Reply to
w_tom

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.

Reply to
gfretwell

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

Reply to
Bob

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 . 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--

Reply to
Bud--

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.

Reply to
trader4

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.

Noth> I had a similar experience, where my PC and Fax machine, which were

Reply to
w_tom

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.

Reply to
trader4

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.

Reply to
w_tom

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