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Electronics Forum / Basics / September 2007Surge protection without grounded plugs
My son just moved into an older house near his college. We're told that the electricity isn't entirely reliable and that he should use a surge protector. The house's plugs aren't grounded. Will this affect the efficacy of a surge protector? Is the computer at risk or just the AC adapter? Any recommendations would be appreciated. TIA, David > My son just moved into an older house near his college. We're told > that the electricity isn't entirely reliable and that he should use a [quoted text clipped - 8 lines] > TIA, > David Hi, Dave. Surge protectors are supposed to work by absorbing the energy of voltage spikes caused by lightning and such. A typical surge protector will absorb the extra energy of the spike, and shunt the current to ground. That means they're not too useful without the GND pin on the plug. But voltage spikes probably aren't the problem here. This sounds more like bad wiring, unbalanced loading of the pole transformer, or poor/ intermittent connections to the line neutral of the transformer. That will mean the line voltage at the plug may go way up or way down, depending on loading, humidity/condensation, the phase of the moon, or whatever. Surge protectors don't do anything about undervoltage, which can destroy a PC as easily as overvoltage. And if the voltage gets high enough, the surge protector will just be destroyed by sustained overvoltage. I'd really suggest the house wiring get checked out by someone competent. After all, your kid is going to be living there. Barring that, and assuming they've got working smoke detectors there (check yourself), a line conditioner might be a better choice for protecting the computer. A line conditioner is an autotransformer that senses the incoming line voltage, and switches taps (raising or lowering the voltage) to compensate. Since a college kid's computer is a mission-critical piece of equipment, the money will be well spent. For a standard computer and laptop setup, one like the TrippLite LC1200 should be sufficient. If the system's a laptop only, you can get away with less. When you've got kids, there's no safety this side of the grave, I guess. Good luck Chris > > My son just moved into an older house near his college. We're told > > that the electricity isn't entirely reliable and that he should use a [quoted text clipped - 10 lines] > surge protector will absorb the extra energy of the spike, and shunt > the current to ground. It does no such thing at all. A typical varistor based surge protector works by clamping the live to neutral voltage. Diverting current to ground is potentially hazardous. Here's an example. Note that the ground simply passes through with no connection to the protection components. The one shown also has a gas discharge tube. http://www.epanorama.net/documents/surge/surge_ac.html Graham >> > My son just moved into an older house near his college. We're told >> > that the electricity isn't entirely reliable and that he should use a [quoted text clipped - 24 lines] > > Graham Here's another one that does not rely on the safety ground: http://brickwall.com/howwork.htm There is some good info here: http://www.mcgsurge.com/mcg_faq.htm http://computer.howstuffworks.com/surge-protector.htm/printable http://www.totse.com/en/technology/computer_technology/surge.html http://www.surgeassure.com/faq.asp If the two-prong outlets cannot be rewired, it might be a good idea to connect an external safety ground to the chassis of the computer or other appliance. A cold water pipe might be good enough, especially if it is copper. Otherwise a driven ground rod is pretty good. A UPS might be another option, especially if the power is noisy or intermittent. But the safest option is a properly installed electrical system. Paul > There is some good info here: > ... > http://computer.howstuffworks.com/surge-protector.htm/printable Please do not cite HowStuffWorks as honest or accurate. It even contradicts what your other citations say. It is so full of outright lies and myths that this criticism only address the errors from a first few pages: Experience with household appliances exposes those myths - described in: "Computer problem need help" posted on 1 Aug 2002: http://tinyurl.com/yqyah >HowStuffWorks on surge protectors is riddled with errors. One > example is obvious based upon what happens in your own home. > From HowStuffWorks: >> A more common cause of power surges is the operation of >> high-power electrical devices, such as elevators, air >> conditioners and refrigerators. >> There is some good info here: >> ... [quoted text clipped - 15 lines] >>> high-power electrical devices, such as elevators, air >>> conditioners and refrigerators. I agree that "How stuff works" is not the best, but motor loads can and do create power surges. The surge may appear on the same phase as the load, due to inductive "kick", but also the starting current in one phase can cause enough voltage drop through the neutral to produce a higher voltage in the opposite phase. If the neutral line is damaged or improperly connected, the two 120V legs may be unbalanced depending on the individual loads. Paul As I'm not an electrician (that should be obvious from my initial post), I admit to having a hard time sifting through all of this stuff. My take is that: - a plug-in surge protector of any type won't protect my son's computer - what is required is for the entire house to be surge protected before the power enters the house. Are these the correct conclusions? TIA, David > As I'm not an electrician (that should be obvious from my initial > post), I admit to having a hard time sifting through all of this [quoted text clipped - 6 lines] > > Are these the correct conclusions? There are several kinds of power problems, and each one has certain risks and means of protection. A surge protector for the entire house, at the service entrance, is probably the best, because it deals with the surge before it enters the rest of the wiring. But it is expensive and requires an electrician to install it. Properly installed and grounded wiring is very important, for the safety of humans as well as equipment. It would be worthwhile to rewire the circuit that feeds the computer, or even run a new line, if possible. Depending on the age of the house, it's possible that the wiring could be aluminum, which often develops poor connections, and can cause all sorts of problems, including fire. Surges from lightning are the most serious, and it is difficult to achieve 100% protection. The best method is to unplug the computer, and remove any phone lines or other external connections. I have even had computer speakers damaged by a close lightning strike that also damaged my modem. Plug-in surge protectors offer some level of protection. I have a surge protector and a UPS on my computer, and they probably helped, but the main surge probably came in through the phone line, which was actually damaged and required a repair to the cable from the pole to the house. I have pictures of the damage caused by the lightning. It apparently came down the wet bark of a huge sycamore tree, and then arced to the phone line as well as the power lines (and blew open the neutral): http://www.smart.net/~pstech/Lightning/ Paul > As I'm not an electrician (that should be obvious from my initial > post), I admit to having a hard time sifting through all of this > stuff. My take is that: > > - a plug-in surge protector of any type won't protect my son's > computer From WHAT ? Gremlins ? Why do you think that ? > - what is required is for the entire house to be surge protected > before the power enters the house. > > Are these the correct conclusions? It all depends what level of protection you want. Graham > As I'm not an electrician (that should be obvious from my initial > post), I admit to having a hard time sifting through all of this [quoted text clipped - 9 lines] > TIA, > David No. You don't know if the "unreliability" you heard about has to do with surges or not. Suppose, for example, that "unreliability" means there are frequent power outages. All the surge protection in the world won't address that problem. If you want to use surge protectors, the IEEE recommends that you use both whole house and point of use protectors. Ed > .... My take is that: > - a plug-in surge protector of any type won't protect my son's [quoted text clipped - 3 lines] > > Are these the correct conclusions? Points are correct IF surges are the problem. But surges have nothing to do with unreliable wiring. Surges are sourced externally. Unreliable wiring is an internal problem. Also irrelevant are surges from household appliances such as motors. If those were destructive, then everyone here is trooping daily to the hardware store to replace clock radios and dimmer switches. Protection already inside all appliances makes those motor 'surges' completely irrelevant. Unreliable wiring would create problems such as power loss, fire, or repeated circuit breaker tripping. Those internally generated events are different externally sourced events such as surges. One symptom of unreliable wiring is extension cords - a common source of fire and why Arc Fault circuit breakers are now required for bedroom circuits. Ground fault breakers are a solution for circuits that are only two wire - do not have the safety ground wire. Also a threat are multiple outlet connectors (such as power strips) that do not have the 15 amp circuit breaker. As noted repeatedly (and why HowStuffWorks is so embarrassing), all appliances contain internal protection. Computers are particularly robust. Protection for all appliances means earthing anything so massive as to cause failures. Surges that may overwhelm protection inside electronic appliances must be earthed before entering the building. Those destructive surges typically occur once every seven years - a number that varies significantly even within the same town. We earth 'whole house' protection for that rare event. Again, every incoming utility wire must be earthed. Telco 'installed for free' protector must connect each phone wire to same earth ground used by AC electric and cable TV. Destructive type of surge seeks earth ground. It is not stopped or absorbed. It must be diverted or shunted to earth. A little one inch part inside a 'magic box' does not even claim to stop or absorb what three miles of sky could not. Connect every incoming wire inside every cable to earth ground either directly (cable TV, satellite dish) or via a protector (AC electric, telephone). > .... My take is that: > - a plug-in surge protector of any type won't protect my son's [quoted text clipped - 3 lines] > > Are these the correct conclusions? Points are correct IF surges are the problem. But surges have nothing to do with unreliable wiring. Surges are sourced externally. Unreliable wiring is an internal problem. Also irrelevant are surges from household appliances such as motors. If those were destructive, then everyone here is trooping daily to the hardware store to replace clock radios and dimmer switches. Protection already inside all appliances makes those motor 'surges' completely irrelevant. Unreliable wiring would create problems such as power loss, fire, or repeated circuit breaker tripping. Those internally generated events are different externally sourced events such as surges. One symptom of unreliable wiring is extension cords - a common source of fire and why Arc Fault circuit breakers are now required for bedroom circuits. Ground fault breakers are a solution for circuits that are only two wire - do not have the safety ground wire. Also a threat are multiple outlet connectors (such as power strips) that do not have the 15 amp circuit breaker. As noted repeatedly (and why HowStuffWorks is so embarrassing), all appliances contain internal protection. Computers are particularly robust. Protection for all appliances means earthing anything so massive as to cause failures. Surges that may overwhelm protection inside electronic appliances must be earthed before entering the building. Those destructive surges typically occur once every seven years - a number that varies significantly even within the same town. We earth 'whole house' protection for that rare event. Again, every incoming utility wire must be earthed. Telco 'installed for free' protector must connect each phone wire to same earth ground used by AC electric and cable TV. Destructive type of surge seeks earth ground. It is not stopped or absorbed. It must be diverted or shunted to earth. A little one inch part inside a 'magic box' does not even claim to stop or absorb what three miles of sky could not. Connect every incoming wire inside every cable to earth ground either directly (cable TV, satellite dish) or via a protector (AC electric, telephone). > My son just moved into an older house near his college. We're told > that the electricity isn't entirely reliable and that he should use a [quoted text clipped - 3 lines] > surge protector? > Is the computer at risk or just the AC adapter? Myth purveyors will claim that a surge protector will absorb energy. Energy that could not be stopped even by three miles of sky. Protectors don't stop or absorb surges (except where myths are promoted). Protection means surges are earthed before entering the building. That energy must be dissipated somewhere. That somewhere is earth ground. A protector is nothing more than a connecting device to protection. Protection is earth ground - where energy is absorbed. Essential is to have breaker box earthing upgraded to both meet and exceed post 1990 NEC code. That means an earthing electrode with a 'less than 10 foot' connection to the breaker box. Chances are the only earthing (if it still exists) was to a cold water pipe. That earthing is no longer sufficient even for human safety. For transistor safety, one 'whole house' protector connected to that upgraded earthing means massive transistor protection. Protection without rewiring the entire house. Every incoming utility must enter at a same location to also make that short earthing connection. For example, the phone line has a 'whole house' protector installed for free by the telco. But that protector, also, is only as effective as its earth ground. Even the cable must be earthed to that same electrode before entering the building. Cable is protected without a protector. No reason for a cable protector. Cable is earthed directly with no protector. Again, what provides the protection? A box? No. Earthing is the protection. What even makes a Franklin lightning rod effective? Sharp or blunt rod? Not relevant. Even a lightning rod is only as effective as its earth ground because earthing provides the protection. Do not confuse safety ground in AC wall receptacles with earth ground. They are electrically different. That AC wall safety ground is for human safety. No surge protector will correct that missing safety ground. Far more useful on 'that' unreliable wiring is to replace selective circuit breakers with Arc fault breakers or GFCI breakers. Unreliable wiring is a human safety problem. A surge protector accomplishes zero. But again, read numeric specs for that surge protector. What does it actually claim to accomplish? Don't read its color glossy sales brochure. What do its numeric specs says it does? It would help if you define which problem needs protection from AND to define "unreliable wiring". A breaker box GFCI circuit breaker goes a long way to protecting from unreliable wiring. An arc fault type is even better protection. The plug-in surge proetctor does nothing. It's own manufacturer will (quitely) recommend not using a power strip protector if receptacles are not three wire - a human safety threat created by connecting a three prong power strip to a two prong outlet. Surge protectors are only connecting devices to protection. That protection is earth ground. If too far away from earth ground, a surge proetctor must shunt somewhere. It may shunt (connect, divert, clamp) a surge to earth via the computer. The effective protector earths before surges can enter the building. A surge properly earthed will not be inside the building to overwhelm protection already inside all appliances. All appliances contain any protection that would work on its power cord. Internal protection that may be overwhelm if the rare and destructive surge is not earthed BEFORE entering the building. >> My son just moved into an older house near his college. We're told >> that the electricity isn't entirely reliable and that he should use a [quoted text clipped - 66 lines] > rare and destructive surge is not earthed BEFORE entering the > building. You don't have any clue what your talking about? Really, be honest! The earth ground is only there for a direct ground reference and a low resistance path to ground. The problem with neutral and hot is that if they are wired incorrectly they can easily kill someone. By having a direct reference to ground you can eliminate this if it is used properly. It also supplies a lower resistance to ground than the neutral(atleast as far as I have seen in my own house). But in any case an earth ground an a neutral are identical in most cases except for some small potential difference(atleast they should be in any properly wired home). I suggest you read up on http://en.wikipedia.org/wiki/Ground_and_neutral As far as surges go, you have essentially varistors that provide a very low resistance path for a high voltage spike. This essentially takes out the load after the varistor preventing(hopefully) most of the current from going through the load. For example, if you have Hot -------+---- Load---+ | | Varistor | | | Neutral ---+------------+ And if a large voltage spike occurs then the varistor acts somewhat as a short essentially resulting in a short from hot to neutral and therefor essentially dissconnecting the load from the mains. (atleast in theory it would do that) This has nothing to do with ground and you could even tie the varistor from ground to netural(although it would not work if the ground was cut). The varistor only stops surges though and doesn't protect in other others. If the varistor breaks then so do the surge protection. In any case "surge" protection doesn't need ground as netural is suppose to be approximately equivilent to ground. The reason for "earth ground" in a plug is for safety reasons and not surge protection. Its a fact that neutral must also exist to complete the circuit so you can always get surge protection... its also true that simple surge protectors are not all that great. Using a simple MOV doesn't protect the load all that great but its better than nothing and can't hurt. So if the OP is only concerned with surge protection then he can do that by buying good surge protectors... having earth ground isn't going to have any effect except it could potentially make the surge protector a little better if it was designed to use it. Maybe it could use a something like + -----+ / \ MOV1 MOV2 / \ - -+--MOV3-+--GND Where if the ground was hooked up properly then you'll have better surge protection... but there are better methods. The extra earth on plugs is only for safety. So what does the typically destructive surge seek? Earth ground. Why must those earthing wires be so short? Well let's finish the math. An AC wall receptacle is maybe 50 feet from the breaker box. IOW it is maybe 0.2 ohms resistance. But the same wire is something like 130 ohms impedance to the surge. What happens when a power strip protector attempts to earth a trivial 100 amp surge via neutral wire? 13.000 volts difference. Will a surge use the 13,000 volt wire to obtain earth? Of course not. It will also find other path to earth via furniture, wall paint, baseboard heater, etc. The AC receptacle ground is safety ground. But the destructive surge, if permitted at the appliance, will find every path to earth - destructively. The effective protector earths before that surge gets anywhere near to appliances. Your MOVs protectors do protect from the type of surge as exampled. Do appreciate that it is not the type of surge that typically causes damage. Surge that damaged electronics seeks earth ground. Its energy must be dissipated somewhere. If not dissipated in earth, then it dissipates destructively via household appliances in a path to earth. If the MOV protector is grossly undersized as is common with many plug-in protectors, then even these scary pictures can result: http://www.hanford.gov/rl/?page=556&parent=554 http://www.westwhitelandfire.com/Articles/Surge%20Protectors.pdf http://www.ddxg.net/old/surge_protectors.htm http://www.zerosurge.com/HTML/movs.html http://tinyurl.com/3x73ol or http://www.esdjournal.com/techpapr/Pharr/INVESTIGATING%20SURGE%20SUPPRESSOR%20FI RES.doc I appreciate the spirit of your reply. But you have completely ignored some critical facts. Typically destructive surge seeks earth ground. It may be completely ignored by your three MOV protector. Or your three MOV protector may even give the surge more paths to find earth, destructively, via adjacent appliances. The surge you have discussed is typically made irrelevant by protection already inside appliances. Anything that a power cord protector might accomplish is already inside appliances. What can overwhelm protection inside appliances? A type of surge that seeks earth ground. We earth this typically destructive surge before it can enter the building - and with only one properly sized protector. Then massive energy of this far more destructive surge is dissipated in earth - does not find destructive paths to earth via household appliances. What provided the protection? What dissipates surge energy? Does that silly little MOV absorb such surges? Of course not. Surge energy must dissipate somewhere. Earth is where surge energy is dissipated. No earth ground means no effective protection from a type of surge that typically cause appliance damage. Appreciate that I have understood earthing for probably longer than you have existed. You are even confusing low resistance earthing with low impedance. Appreciate why a connection to earth ground must be 'less than 10 feet' - and other critical factors. If you don't understand those numbers, then you have not yet learned the many functions performed by earthing. Of course this is well beyond what the OP was asking. Chances are the building is so old as to not even have any earthing - a major human safety problem as well as making a surge protector completely ineffective. On Sep 24, 12:54 am, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote: > You don't have any clue what your talking about? Really, be honest! > [quoted text clipped - 62 lines] > > The extra earth on plugs is only for safety > So what does the typically destructive surge seek? Earth ground. > Why must those earthing wires be so short? Well let's finish the [quoted text clipped - 58 lines] > human safety problem as well as making a surge protector completely > ineffective. I guess your the god of earth ground? Please... nots not get into some silly fight over such an issue. I believe you are confusing safety with surge protection. Surge protectors are not decides with saftey in mind but only to protect the equipment involved to some degree. I agree that safety is an issue and I agree its best to have earth ground. Hell, maybe they would put a piece of rebar driven into the ground where every recepticle is along with some type of external surge protection for the whole house? But the fact of the matter is that is that many devices use only hot and netural without any earth ground even whe its available(go look at your toster and any small appliance). In any case my point is that surge protectors themselfs do not need earth ground. I never said it was a good idea not to have them but you claimed they are completely ineffective without earth ground and this is simply not the case. They do exactly what they were designed to do with out any earth ground... infact if you open one up, at least in a cheap one, you will not see the surge protection circuitry use earth ground at all. The only thing I really disagree with you on is that surge protectors, and here I'm implicitly refering to the common ones that the average person can buy, do not need earth ground to protect against your average surge and minimize damage to the device connected. It greatly minimizes the damage to devices connected compared to not having anything at all(Even if you have earth ground). Is it the ultimate solution? Can you stop all surges and prevent all possible saftey hazzards? No. But you can increase your chances to device failure by 1000x(I'm just making that number up but seems resonable) by adding even a cheap surge protector(a simple mov). Of course even that introduces some saftey issues as you have proven by your links... MOV's are perfect and if they short out then you can have a serious saftey problem. Anyways... > The only thing I really disagree with you on is that surge protectors, and > here I'm implicitly refering to the common ones that the average person can > buy, do not need earth ground to protect against your average surge and > minimize damage to the device connected. It greatly minimizes the damage to > devices connected compared to not having anything at all(Even if you have > earth ground). You have assumed the only surge protector available to a layman is power strip (plug-in) type. A layman must buy multiple plug-in protectors sold by less responsible companies such as Tripplite, Belkin, APC, Monster Cable, etc. for much more money. Or a layman can purchase one effective protector sold by well respected companies. Names understood by any guy who visit electrical supply departments even in Lowes or Home Depot. Effective protector with a dedicated earth ground is sold to layman by GE, Siemens, Cutler-Hammer, Intermatic, Leviton, Square D and others. An effective protector costs tens (maybe 100) times less money per protected appliance. That 'so expensive' plug-in protector can even contribute to damage of an adjacent appliance. No earth ground means it must earth that surge somewhere. Published is this very first conclusion in one 1996 IEEE paper: > Conclusion: > 1) Quantitative measurements in the Upside-Down house clearly > show objectionable difference in reference voltages. These occur > even when or perhaps because, surge protective devices are > present at the point of connection of appliances. Which one of us traced a surge destructively through a plug-in protector; earthed that surge, destructively, through adjacent computers. BTW, that plug-in protector did what its numerical specifications claim. I and this IEEE author witnessed the same problem. Again you have assumed only one kind of surge - the one that is not typically destructive. Again, you are ignoring what the typically destructive surge seeks - earth ground. Again, you are ignoring wire impedance - or why that earthing connection must be so short. Again, where is the surge energy dissipated? What happens if that plug-in protector grounds a surge on neutral wire? A transient is then induced on all other adjacent wires - more transients inside a building. Where is the protection? Just another reason why the plug-in solution is ineffective. Nothing new here. What is required for surge protection was well proven even 80 years ago. The principles are based in what Ben Franklin demonstrated in 1752. Protection without earthing was not effective. Ham radio operators would even disconnect antenna leads, put that connector inside a mason jar, and still suffer damage. When did the damage stop? When the antenna was earthed. Why? Effective surge protection is always about earthing surges. Does your telco install plug-in protectors adjacent to their $multi- million switching computers? Of course not. Your telco does not waste money on ineffective and grossly expensive devices. Your telco installs protectors to be more effective AND cost less money. To make protection even better, your telco installs a better earthing system. Better earthing makes better protectors. Jon. You claim earthing is not essential? Why is earthing THE most critical part of every protection system including your telco's surge protection? They don't shutdown for every thunderstorm. They cannot suffer surge damage. Their computer is connected to overhead wires all over town. Each thunderstorm may result in 100 surges. Why does the telco not suffer damage? Their protectors connect as short as possible to earth ground. Tto make that protection even better, a telco wants that protector up to 50 meters distant from electronics. Appreciate the separation that also makes a protector more effective. Short to earth ground and separated from electronics means better protection. How curious. Homeowners can obtain same protection in one 'whole house' protector with proper earthing. What follows are example after example; what both professionals and experience teach. In literally every IEEE paper on surge protection, what is always required? Earth ground. How did van der Laan and Deursen correct surge damage in a nuclear hardened, Norwegian, maritime radio station in their 1998 IEEE paper? They fixed the earthing. They corrected how protectors were earthed. How did another construct a radio station so as to not suffer damage from direct lightning strikes? http://scott-inc.com/html/ufer.htm The NIST defines what a protector does on page 6 (Adobe page 8 of 24) . http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf > You cannot really suppress a surge altogether, nor > "arrest" it. What these protective devices do is > neither suppress nor arrest a surge, but simply > divert it to ground, where it can do no harm. Another professional with decades of experience describes protection: http://www.harvardrepeater.org/news/lightning.html > Well I assert, from personal and broadcast experience spanning > 30 years, that you can design a system that will handle *direct [quoted text clipped - 15 lines] > That's most generally a low *inductance* path rather than just a > low ohm DC path. Jon - how many decades ago were you building these systems; learning from experience? How many decades ago were you tracing surge damage by even replacing semiconductors to make electronics completely functional? You claim we all have been wrong all this time? You did not even know about wire impedance - why the earthing wire must be so short, no sharp bends, separated from other wires (which is why the ground or neutral wire inside Romex is not sufficient for earthing), no splices, not inside metallic conduit, etc. Why do we know about things so important for earthing? Do you even know why that wire must not be inside metallic conduit? How many semesters did you take in Electromagnetic Wave Theory? Jon. Again I appreciate your spirit. But your analysis completely ignores fundamental electrical concepts. Do you know why wire inside conduit makes a bad surge conductor? You did not even answer this question - where does surge energy get dissipated? If not earth, then where? You have recommended protection from one type of transient that is made irrelevant by standard electronic designs. Where is surge energy dissipated? Earth ground is where that energy is dissipated without damage. How did Orange Country stop surge damage to their emergency response facilities? Did they install plug-in protectors? Of course not. Orange County fixed their earthing systems - nothing more: http://www.psihq.com/AllCopper.htm Defined was a 'whole house' protector - a *secondary* protection system. What is the center of that system? Building earth ground. What is *primary* protection? A homeowner should also inspect the essential component of their *primary* protection system: http://www.tvtower.com/fpl.html Where surge damage is not acceptable, earthing is the one component always required for effective protection. A protector is only as effective as its earth ground. Some protection systems don't even require a protector - but always require earthing. How many examples of professionally installed solutions were provided? 15? Of course, none of this addresses human safety problems created by unreliable wiring - an internal problem. Earthing is also important for human safety reasons as well as for transistor safety. This is about earthing to avoid externally source problems. One properly earthed protector is - by far - the most effective solution and the best solution per dollar. It is the only solution for a house with two wire receptacles. Too many older homes are missing an earthing system - let alone one that both meets and exceeds post 1990 National Electrical Code requirements. We are not discussing 100% protection. Discussed is protection that is well over 90% effective. Earthing both for transistor safety and for human safety. Even those 'scary pictures' demonstrate the pathetic nature of plug-in protectors - near zero proteciton. Don't agree? Then where does that plug-in protector's specs even claim protection from the type of surge that does damage? It does not. Those cheap plug-in protectors may even earth surges, destructively, through adjacent electronics. No earth ground means no effective protection. Even worse, those cheap protectors cost tens of times more money per protected appliance - are more expensive as well as ineffective. The effective protector costs about $1 per protected appliance. The only effective protector is the one that can earth typically destructive surges. How many of your protector designs have been tested by direct lightning strikes? Well, show us how fifteen times over how all this is wrong. Explain the importance of wire impedance. Explain where surge energy is dissipated. Explain how to a plug-in protector stop surges from seeking eath ground. Explain why the plug-in manufacturer does not even claim protection. Explain why so many professionals are wrong. Instead, a protector is only as effective as its earth ground. I appreciate what you have posted. But it is what you don't know that has led you to erroneous conclusions. One glaringly obvious problem. Where is the surge energy dissipated? Another obvious problem. Why do locating that cannot suffer damage not use the protectors you have recommended? > Another professional with decades of experience describes > protection: [quoted text clipped - 31 lines] > > How many semesters did you take in Electromagnetic Wave Theory? Actually I probably know more about EM theory than you. Do you know anything about Tensors, the Retarded Curl theorems, Vector Laplacians, Relativistic Maxwels equations, etc..? I doubt it... I'm not ignoring anything and infact I'm taking into account much more than you. Your ignoring the cost it takes to rewire a house for earth ground. The fact that neutral is earth ground but usually exists at a slightly higher potential because of resistance. The fact of the matter is that you might be right in theory but for all practical reasons your wrong. Sure one shouldn't but a price on life but the fact of the matter is, is that people do it every day. Now since your such an expert and believe in having earth grounds outweigh any cost then why not do it for the guy for free? Why don't you also compaign to get all applicances to support earth ground? Can you do me a favor though? Can you look at the number of people killed a year by toasters? How bout electrical shocks from appliances in general? How bout electricity in general? Compare that with people dieing by car crashes. The fact is your a saftey nutt. There are hundreds of millions of homes in the world that don't use earth ground and very few people die from it. A properly designed device can go a long why without earth ground. All earth ground is is a extra measure of safety. If they wanted you could add 10 earth grounds and it wouldn't make a device any safer if it wasn't used properly and wouldn't add anything over just one ground(for obivous reasons). I never claimed that earth ground was evil or bad... but there are practical considerations that you easily overlook. The OP said "The house's plugs aren't grounded. Will this affect the efficacy of a surge protector? Is the computer at risk or just the AC adapter?" And the f.cking fact of the matter is that earth ground plays no role in the efficiency because netural is approximately earth ground(in theoretically they should be equivilent if it wasn't for resistance). This is why your wrong in that you keep arguing about something that no one asked. Now if he asked about the safety it would be an entirely different matter... and its ok to point out that rewiring the house would go a long way for safety factors. Now if you really want to prove to me that your write about the OP's question and that I'm wrong then show me a circuit that improves(significantly) its surge capabilities by using earth ground over one that doesn't. Talking about safety has nothing to do with it cause I don't give a sh.t about that. Its not what the OP asked and I'm sure many people have pointed how why earth ground is used. You can beat that nail to death but it isn't going to change anything. You can also talk about how you have been rewiring houses since you were a baby sh.tting in your diapers and pissing in your mouth but it doesn't change any of the facts. If you want to try and prove something then do it with science and not authority cause I don't give a sh.t if your the president of the electrical satefy club at your local HS. Show me a circuit that significantly increases the surge protection that uses earth ground to accomplish it over the best that can be done without out using ground. Why not the worse? Because then you'll show me a circuit without any protection and any ground and claim one with a ground and MOV works better. Jon Slaughter is not ignoring anything? Your post even ignores what the original poster asks. There is no major rewiring cost. Necessary for both human safety and surge protection is an 8 foot earth rod and less than 10 feet of bare copper 6 gauge wire. Where is this massive cost? Why do you also trivialize that cost by justifying "a price on human life"? Why do you post about people killed by toasters? David Schwartz asked nothing about toasters. Jon completely ignores his problem and ignores industry standard solutions. Why, Jon, do you recommend plug- in protectors that do not provide effective protection (don't even claim to provide protection) and that are even a safety threat on two wire receptacles? An effective protector has a short earthing connection. A plug-in protector has all but no earthing when too far from earth ground and too close to an appliance. A human safety threat is also demonstrated by 'scary pictures' of grossly overpriced and ineffective plug-in protectors. Even a report from a North Carolina Fire Marshall notes how 'protector' fires may be mistakenly blamed on an overload. Did you learn from any of those citations? Why do you even ignore: > You cannot really suppress a surge altogether, nor > "arrest" it. What these protective devices do is > neither suppress nor arrest a surge, but simply > divert it to ground, where it can do no harm. Jon recommends a plug-in protector? He also recommends leaving earth grounds missing because human safety is irrelevant? Jon did not understand meaning of 'divert' in that above quote? He recommends a device that requires earth ground but does not even have a safety ground? Jon erroneously assumes those two grounds are same because he does not even comprehend the significance of wire impedance and the importance of 'divert'. Jon provides no technical facts to support his supposition. Jon recommends multiple plug-in protectors that don't even claim to provide protection. Jon recommends not upgrading a building's earth ground that provides both human safety and transistor safety. He says it is too expensive. Meanwhile neither safety ground nor neutral wire does anything effective. Simple wire impedance (a 13,000 volt example) makes that obvious. Jon even ignored citations that repeatedly answered this: > Show me a circuit that significantly increases the surge protection > that uses earth ground to accomplish it over the best that can be > done without out using ground. Standard solutions were provided how many times - 15 - 20? Did you read any of them? > Well I assert, from personal and broadcast experience spanning > 30 years, that you can design a system that will handle *direct > lightning strikes* on a routine basis. ... When effective protection is installed, in every case, earthing defines each layer of protection. When protection was ineffective, what did they do? Did they install plug-in protectors? Of course not. They required a solution - not a scam. They fixed earthing in the Orange County FL emergency response center: http://www.psihq.com/AllCopper.htm But again, cited are technical reasons - not claims punctuated with 'sh.t' and 'f.cking'. Jon, do you have anything technical to post - such as the numeric specification from that plug-in protector that even claims protection from each type of surge? Where are those numbers? Jon, you even confuse wire resistance with wire impedance (why connections must be short, no sharp bends, not inside metallic conduit, etc). With basic electrical knowledge, then you would understand why wire impedance is so critically important. You would know why the US Air Force requires all protectors at the service entrance and why an industry benchmark - Polyphaser - discussed earthing extensively. You don't possess technical experience of simple electrical concepts AND you obviously never worked where effective protection is routinely installed. With experience, then you have seen where a plug-in protector earthed a surge, destructively, through adjacent electronics. With experience, then you would know that earth rod and 6 AWG wire is inexpensive. You even trivialize human safety; even justify unnecessary risk by citing a toaster. Do you know anything about earthing or safety ground other than what is in a Wikipedia article? Apparently not based upon what you have posted. Older homes with two wire receptacles typically do not have sufficient earthing. Often that earthing is even missing. In one case, a house even exploded because earthing was missing. The original poster is encouraged to inspect - maybe upgrade - earthing that provides both human safety and transistor safety. Jon never knew what is "the cost it takes to rewire a house earth ground". That cost is known trivial when one has knowledge and experience. On Sep 24, 10:59 pm, "Jon Slaughter" <Jon_Slaugh...@Hotmail.com> wrote: > ... > I'm not ignoring anything and infact I'm taking into account much more than [quoted text clipped - 60 lines] > without any protection and any ground and claim one with a ground and MOV > works better. > No earth ground means > it must earth that surge somewhere. Published is this very first > conclusion in one 1996 IEEE paper: >> Conclusion: What does the 1994 (not 1996) paper really say about plug-in suppressors: "Mitigation of the threat can take many forms. One solution. illustrated in this paper, is the insertion of a properly designed surge reference equalizer [multiport plug-in surge suppressor]." In 2001 the same author wrote the NIST guide which says plug-in suppressors work. Because plug-in suppressors violate w_'s religious belief in earthing he has to twist what Martzloff says about them. > Again, you are ignoring what the typically > destructive surge seeks - earth ground. Again, you are ignoring wire > impedance - or why that earthing connection must be so short. Again, > where is the surge energy dissipated? Never fly in an airplane. They do not have the required short connection to earth to protect against surges and lightning strikes. (Jon is so stupid - he thinks airplanes are safe.) > What happens if that plug-in protector grounds a surge on neutral > wire? A transient is then induced on all other adjacent wires - more > transients inside a building. Where is the protection? Just another > reason why the plug-in solution is ineffective. Surges that come into a house on the neutral wire are directly earthed by the neutral-ground bond in US power services. A plug-in suppressor clamps the voltage on all wires to the common ground at the suppressor. The voltage on the wires going to the protected equipment is safe for the equipment. The IEEE guide explains that earthing occurs elsewhere. > Does your telco install plug-in protectors adjacent to their $multi- > million switching computers? Of course not. What a surprise! telcos don’t use plug-in suppressors to protect high amp hard wired switches with thousands of signal wires that would have to go through the suppressor. > The NIST defines what a protector does on page 6 (Adobe page 8 of > 24) . > http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf What does the NIST guide really say about plug-in suppressors? They are "the easiest solution". and: "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances, No for two-link appliances [equipment connected to power AND phone or CATV or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless." Because plug-in suppressors violate w_'s religious belief in earthing he has to twist what the NIST guide says about them. > How did Orange Country stop surge damage to their emergency response > facilities? Did they install plug-in protectors? Of course not. > Orange County fixed their earthing systems - nothing more: > http://www.psihq.com/AllCopper.htm w_ has a fetish about tower antennas (including some other links). If you plan on erecting a 280 foot lightning rod (aka. tower antenna) in your yard and connecting it to equipment in your house this may be relevant. But not for the rest of us. > It is the only solution for a house with > two wire receptacles. Service panel suppressors are a good idea. They may not practical for the OP because the house is probably rented. If relying only on a service panel suppressor, make sure the phone, cable, ... entry protectors are connected with a *short* wire to the earthing wire at the power service. Without a short wire, a high voltage can develop between power and signal wires that can damage equipment connected to both. That is why the NIST guide, above, says “No for two-link appliances”. (That does not cover all surge possibilities, like voltage from cable center conductor to shield.) > Then where does that plug-in protector's > specs even claim protection from the type of surge that does damage? > It does not. Complete nonsense. > The > effective protector costs about $1 per protected appliance. If you count light bulbs and outlets as appliances. > Instead, a protector is only as effective as its earth ground. The requires statement of religious belief in earthing. Everyone is for earthing. The only question is whether plug-in suppressors work. Both the IEEE and NIST guides say they are effective. w_ has no links in his post that says plug-in suppressors are NOT effective. And no answers to the great questions of age: - Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors? - Why does the NIST guide says plug-in suppressors are "the easiest solution"? - Why did Martzloff’s paper say “Mitigation of the threat can take many forms. One solution ... is the insertion of a properly designed [multiport plug-in surge suppressor].” -- bud-- > So what does the typically destructive surge seek? What SURGE ? A voltage transient across live and neutral 'seeks' nothing. There seems to be some huge myths about 'surges'. Graham On Sep 24, 2:31 pm, Eeyore <rabbitsfriendsandrelati...@hotmail.com> wrote: >> So what does the typically destructive surge seek? > > What SURGE ? > A voltage transient across live and neutral 'seeks' nothing. The surge seeks earth ground. A typically destructive surge destroys chimneys and church steeples - why? It seeks conductive path to earth. How did Franklin avoid that damage? He diverted electricity to earth where the energy was absorbed. What makes Franklin lightning rods so effective? Its earth ground. A surge on AC electric wires is seeking earth ground. If not earthed before entering a building, then a path to earth may be destructive via appliances. This is the surge that damages household appliances. Any surge between line and neutral is trivial and daily made irrelevant by protection already inside appliances. What type of surge may overwhelm that internal appliance protection? The one that seeks earth ground. What earths that surge? A protector with a short ('less than 10 foot') connection to earth. Meanwhile one 'whole house' protector also makes a 'line to neutral' surge irrelevant. One protector does what multiple plug-in protectors hope to accomplish. Then one 'whole house' protector also protects from a type of surge that actually does appliance damage because it is earthed. > So what does the typically destructive surge seek? Earth ground. > Why must those earthing wires be so short? Well let's finish the [quoted text clipped - 3 lines] > protector attempts to earth a trivial 100 amp surge via neutral wire? > 13.000 volts difference. Of course the neutral does not earth the 100A surge. The IEEE guide has an example of how a plug-in suppressor works (beginning pdf page 40). The suppressor works by CLAMPING the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing. The guide explains *earthing occurs elsewhere*. Because this violates w_’s religious belief in earthing he can’t understand the example. > The effective protector earths before that surge gets anywhere near > to appliances. Both the IEEE and NIST guides say plug-in suppressors are effective. > Your MOVs protectors do protect from the type of surge as exampled. > Do appreciate that it is not the type of surge that typically causes > damage. Surge that damaged electronics seeks earth ground. Bullcrap. Plug-in suppressors work on any surge. For surges coming in on the power line, the neutral-ground bond at the service converts common mode surges into transverse mode surges anyway. > If the MOV protector is grossly undersized as is common with > many plug-in protectors, then even these scary pictures can result: > http://www.hanford.gov/rl/?page=556&parent=554 w_ can't understand his own hanford link. It is about "some older model" power strips and says overheating was fixed with a revision to UL1449 that requires thermal disconnects. That was 1998. > Appreciate that I have understood earthing for probably longer than > you have existed. Perhaps educated beyond his intelligence. w_ is on a crusade against plug-in suppressors. Reliable sources - both the IEEE and NIST guides - say plug-in suppressors are effective. w_ has never found a link that says plug-in suppressors are NOT effective. And w_ has never explained: - Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors? - Why does the NIST guide says plug-in suppressors are "the easiest solution"? -- bud-- > Of course the neutral does not earth the 100A surge. The IEEE guide has > an example of how a plug-in suppressor works (beginning pdf page 40). [quoted text clipped - 3 lines] > elsewhere*. Because this violates w_'s religious belief in earthing he > can't understand the example. Bud claims the protector works by clamping to nothing. Se we review page 42 Figure 8 in his own citation. A protector is adjacent to a TV. It is too far from earth ground. So it clamps? Yes, it clamps the (maybe 100 A) surge 8000 volts destructively through TV2. A surge seeks earth ground. If not clamped to earth (if clamped to nothing) then a surge will increase voltage, as necessary, to obtain earth ground. Page 42 Figure 8 - the surge is earthed 8000 volts destructively through an adjacent TV. Bud promotes for the plug-in protector industry. His protectors don't have a dedicated earthing wire and have massive profit margins. Plug-in protectors that don't even claim to protect from a surge that typically does damage. Furthermore, his protectors cannot be used on two wire receptacles. Bud's post is completely irrelevant to the OP's question - a house with two wire receptacles. One protector that does clamp (shunt, divert, connect) to earth is the protector also used where damage is not an option - the 'whole house' protector. That telephone line protector, installed for free on each subscriber line, also has an earthing wire. A protector is only as effective as its earth ground. Even Bud's citations warn about that need for proper grounding. A plug-in protector can even contribute to appliance damage - page 42 Figure 8. The OP's house does not even have safety grounds - just another reason why his ony option is one 'whole house' protector - properly earthed. >> Of course the neutral does not earth the 100A surge. The IEEE guide has >> an example of how a plug-in suppressor works (beginning pdf page 40). [quoted text clipped - 5 lines] > > Bud claims the protector works by clamping to nothing. Bud repeats what the IEEE guide says - as in the quite above. w_ can not understand because of his religious blinders. > Se we review > page 42 Figure 8 in his own citation. A protector is adjacent to a > TV. It is too far from earth ground. So it clamps? Yes, it clamps > the (maybe 100 A) surge 8000 volts destructively through TV2. The illustration in the IEEE guide has a surge coming in on a cable entry. There are 2 TVs, one is on a plug-in suppressor. The plug-in suppressor protects TV1, connected to it. Without the plug-in suppressor the surge voltage at TV2 is 10,000V. With the suppressor at TV1 the voltage at TV2 is 8,000V. It is simply a *lie* that the plug-in suppressor at TV1 in any way contributes to damage at TV2. The point of the illustration for the IEEE, and anyone who can think, is "to protect TV2, a second multiport protector located at TV2 is required." w_ says suppressors must only be at the service panel. In this example a service panel protector would provide absolutely *NO* protection. The problem is the wire connecting the CATV entry block to the power service ‘ground’ is too long. The IEEE guide says in that case "the only effective way of protecting the equipment is to use a multiport protector." Because plug-in suppressors violate w_'s religious belief in earthing he has to twist what the IEEE guide says about them. > A surge > seeks earth ground. If not clamped to earth (if clamped to nothing) > then a surge will increase voltage, as necessary, to obtain earth > ground. The IEEE guide explains earthing occurs elsewhere. In the illustration in the guide, pdf page 42, the guide explains earthing occurs primarily through the ‘ground’ wire from the cable entry block to the power service (but the wire is too long). > Bud promotes for the plug-in protector industry. To quote w_ "It is an old political trick. When facts cannot be challenged technically, then attack the messenger." My only association with surge protectors is I have some. With no technical arguments, w_ has to discredit those that oppose him. > Plug-in protectors that don't even claim to protect from a surge that > typically does damage. Complete nonsense. > Furthermore, his protectors cannot be used on > two wire receptacles. Bud's post is completely irrelevant to the OP's > question - a house with two wire receptacles. They are not “my” protectors. With 2 wire receptacles there is not a good solution. Plug-in suppressors can be used with 2 wire loads. They could also be used with loads with grounding plugs but the grounds can float. The grounds will also float with service panel suppressors. The accepted practice with a grounding plug is use a GFCI receptacle. Adding a phone or cable connection makes it more likely the GFCI will trip. The best solution is to find a grounded receptacle. > One protector that does clamp (shunt, divert, connect) to earth is > the protector also used where damage is not an option - the 'whole > house' protector. That telephone line protector, installed for free > on each subscriber line, also has an earthing wire. Service panel suppressors are a good idea. But if you rely only on them, make sure the ‘ground’ wire from the phone, cable, ... entry protector makes a *short* connection to the earthing wire at the power service. If not a high voltage can develop between power and signal wires as illustrated in the IEEE guide pdf page 40. That is one reason why the NIST guide says: "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances, No for two-link appliances [equipment connected to power AND phone or CATV or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless." > A protector is > only as effective as its earth ground. The required statement of religious belief in earthing. > A plug-in protector can even > contribute to appliance damage - page 42 Figure 8. The lied repeated. > The OP's house > does not even have safety grounds - just another reason why his ony > option is one 'whole house' protector - properly earthed. It is not the OP’s house. It is the house his son is living in. His son is likely renting. A service panel suppressor is probably not practical for a renter. Everyone is for earthing. The question is whether plug-in suppressors work. Both the IEEE and NIST guides say they are effective. There are 98,615,938 other web sites, including 13,843,032 by lunatics, and w_ can't find another lunatic that says plug-in suppressors are NOT effective. All you have is w_'s opinions based on his religious belief in earthing And still no answers to the great questions of age: - Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors? - Why does the NIST guide says plug-in suppressors are "the easiest solution"? - Why did Martzloff’s paper say “Mitigation of the threat can take many forms. One solution ... is the insertion of a properly designed [multiport plug-in surge suppressor].” - How would a service panel suppressor provide any protection in the IEEE example, pdf page 42? Bizarre claim - plug-in surge suppressors don't work Never any sources that say plug-in suppressors are NOT effective. Twists opposing sources to say the opposite of what they really say. Attempts to discredit opponents. w_ is a purveyor of junk science.  Signaturebud-- >> My son just moved into an older house near his college. We're told >> that the electricity isn't entirely reliable and that he should use a >> surge protector. As others have noted, the problem may be surges or may be other power problems. How common are lightning storms? >> The house's plugs aren't grounded. Will this affect the efficacy of a >> surge protector? >> Is the computer at risk or just the AC adapter? The best information on surges and surge protection I have seen is at: http://omegaps.com/Lightning%20Guide_FINALpublishedversion_May051.pdf - "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005 (the IEEE is the dominant organization of electrical and electronic engineers in the US). And also: http://www.nist.gov/public_affairs/practiceguides/surgesfnl.pdf - "NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001 The IEEE guide is aimed at those with some technical background. The NIST guide is aimed at the unwashed masses. > Myth purveyors will claim that a surge protector will absorb energy. > Energy that could not be stopped even by three miles of sky. > Protectors don't stop or absorb surges (except where myths are > promoted). The IEEE guide explains plug-in suppressors work by CLAMPING the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing). The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40). In the US, UL requires plug-in suppressors have MOVs from H-G, N-G, H-N. Note that all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor. Connecting all wiring through the suppressor prevents damaging voltages between power and signal wires. These multiport suppressors are described in both guides. > A protector is nothing more than a connecting device to protection. > Protection is earth ground - where energy is absorbed. w_ has a religious belief (immune from challenge) that surge protection must use earthing. Thus in his view plug-in suppressors (which are not well earthed) can not possibly work. As the IEEE guide explains, plug-in suppressors do not work primarily by earthing. > Chances are the only earthing > (if it still exists) was to a cold water pipe. That earthing is no > longer sufficient even for human safety. Complete nonsense. Water pipes (10 ft or more buried metal) have had to be used as an earthing electrode in the US for a very long time. > For transistor safety, one > 'whole house' protector connected to that upgraded earthing means > massive transistor protection. A service panel suppressor is a good idea but then you also need a short connecting wire from phone and cable entry protectors to the earthing wire at the power service. The house is likely rented which probably makes a power service panel suppressor impractical. > Every incoming utility must enter at a same location to also make > that short earthing connection. For example, the phone line has a > 'whole house' protector installed for free by the telco. But that > protector, also, is only as effective as its earth ground. Even the > cable must be earthed to that same electrode before entering the > building. The cable and phone building entry protectors must connect with a *short* wire to the earth electrode wire at the power service. A short wire keeps the potential at the power and phone and cable ‘grounds’ the same. In the IEEE example the ‘ground’ wire from the cable entry protector is too long. That allows 10,000V to develop between the cable and power wires. The IEEE guide says in that case "the only effective way of protecting the equipment is to use a multiport protector." The IEEE guide says even 10 foot connecting wire is too long (pdf page 38). Francois Martzloff, the NIST guru on surges and author of the NIST guide, has written "the impedance of the grounding system to `true earth' is far less important than the integrity of the bonding of the various parts of the grounding system." According to NIST guide, US insurance information indicates equipment most frequently damaged by lightning is computers with a modem connection TVs, VCRs and similar equipment (presumably with cable TV connections). All can be damaged by high voltages between power and signal wires. > Cable is protected without a protector. No reason for a > cable protector. Cable is earthed directly with no protector. No reason for a protector? The IEEE guide notes that the voltage between cable center conductor and sheath is limited by the breakdown of F-connectors which is typically 2-4,000V. The guide notes that connected equipment can be damaged at those voltages. Plug-in suppressors are likely to clamp the voltage to a safe level. > Far more useful on 'that' unreliable wiring is to > replace selective circuit breakers with Arc fault breakers or GFCI > breakers. If the wiring to the outlets does not have a ground, in the US equipment with a ground prong on the power cord can be plugged into a GFCI outlet or outlet that is protected by a GFCI. (The outlet needs to be marked “No equipment ground”) The best solution is if the computer can be moved to where there is a grounded outlet. Using a plug-in suppressor without a grounded outlet is not a great idea. Particularly if the equipment plugs have ground pins there is not a great solution. If the plugs are all 2 prong, I would probably use a plug–in suppressor. A plug-in suppressor provides protection without a ground wire, but as the IEEE guide shows, the ground potential can be shifted when the suppressor works. It could also shift the ground potential if the MOVs get ‘leaky’ if hit with many surges. -- bud-- > >> My son just moved into an older house near his college. We're told > >> that the electricity isn't entirely reliable and that he should use a > >> surge protector. > > As others have noted, the problem may be surges or may be other power > problems. How common are lightning storms? Indeed. The house wiring itself won't cause any surges. From what I've heard the OP would be wise to check that the neutral isn't 'floating' though (assuming this is in the USA with the '2 phase' 240V supply). Graham |
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