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Thunder
When I hear thunder, or I'm temporarily away from my XP Home computer and
thunder is predicted, I turn the system and UPS off and unplug the modem telephone line. Overkill? Before I did this I lost the built-in modem to a nearby lightning strike (I assume). However most businesses and many other systems are left on durng storms evidently with no problems. What do you do? TIA -- You know it's time to clean the refrigerator when something closes the door from the inside. |
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Thunder
"KenK" ha scritto nel messaggio
... What do you do? In my house I haven't a SPD (surge protection device), so if the storm is strong I unplug everything: modem telephone line and AC power plugs too. GF |
#3
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Thunder
"G.F." ha scritto nel messaggio
... if the storm is strong I correct: a storm is strong by definition. I intended to say: if the weather is bad enough. GF |
#4
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Thunder
KenK wrote:
When I hear thunder, or I'm temporarily away from my XP Home computer and thunder is predicted, I turn the system and UPS off and unplug the modem telephone line. Overkill? Before I did this I lost the built-in modem to a nearby lightning strike (I assume). However most businesses and many other systems are left on durng storms evidently with no problems. What do you do? TIA Depends on the storm. We rarely get lightning here but when it does, and if nearby, I unplug everything and take a nap. Every electronic device I have is on at least one surge protector. That goes for power and communication wiring. The office does not use surge protectors but then the computers are $300 Dell/HP/etc. Throw away units. The servers are fully protected though. |
#5
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Thunder
On 7 Jan 2016 18:25:38 GMT, KenK wrote:
When I hear thunder, or I'm temporarily away from my XP Home computer and thunder is predicted, I turn the system and UPS off and unplug the modem telephone line. Overkill? Before I did this I lost the built-in modem to a nearby lightning strike (I assume). However most businesses and many other systems are left on durng storms evidently with no problems. What do you do? TIA I agree with everyones. I unplug everything when I notice more frequent lighting and the thunder are getting louder. Personally, I don't have the confidence to trust a surge protector. IMO, if a lightning can jump from the clouds onto the ground, I don't think it's impossible for it to jump a few more millimeters or inches in a surge protector circuit. It can even blow up a thick wood if it gets in its way. Small chance, but it's not impossible. I just rather be safe than sorry. Chances are that it'll strike taller buildings or antennas. My suggestion is to make sure you have a properly installed lightning protection for the house. i.e. a rod at top of the highest part of the house connected to a cable that goes directly into the soil ground. This is not just for your house, but it's for everything in it. Power and phone lines are actually security risk in this matter. For the computer, unplugs everything, move the plugs and their wires (and you) as far away as possible from the power sockets (and phone sockets). Make sure the distance is farther than the distance between the power/phone socket and the soil ground. Would be great if your computer table has wheels so that you can move it too. http://stormhighway.com/surge_protectors_ups_lightning_protection_myth.php |
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Thunder
On Thursday, January 7, 2016 at 1:25:43 PM UTC-5, KenK wrote:
However most businesses and many other systems are left on durng storms evidently with no problems. Many without surge protection talk in terms of 'blocking' or 'absorbing' a surge. How does that 2 cm part inside an adjacent (near zero) protector 'block' what three miles of sky could not? It doesn't. How do its hundreds of joules 'absorb' surges that are hundreds of thousands of joules? It doesn't. When damage occurs, some hype another myth: "nothing can protect from direct lightning strikes". That is true when one ignores well proven science. Your telco's CO suffers about 100 surges with each storm. So your town is without phone service for four days while they replace that $multi-million computer? Of course not. That CO must withstand all surges - including so many that occur without warning - to have no damage. By comparison, unplugging is unreliable - dependent on something very unreliable - a human. Ben Franklin demonstrated protection from direct lightning strikes without damage. Everyone learned this in elementary school science. Many forgot due to what is taught in advertising. Lightning (a typical surge) seeks earth ground. A best connection to earth is maybe 20,000 amps through a wooden church steeple. Wood is not a very good electrical conductor resulting in a high voltage. A high voltage times 20,000 amps is high energy - steeple damaged. Franklin connected 20,000 amps to earth via a rod and good electrical conductor. Good conductor results in a near zero voltage. Near zero voltage times 20,000 amps is near zero energy - nothing damaged. Lightning seeks earth ground. A best connection to earth is maybe 20,000 amps incoming on AC mains through household appliances. Household appliances are not very good electrical conductors resulting in a high voltage. A high voltage times 20,000 amps is high energy - appliances damaged. For over 100 years, the informed connected 20,000 amps to earth via a properly earthed 'whole house' protector (plug-in protectors have all but no earth ground connection). That protector and low impedance (ie less than 10 foot) connection to single point earth ground results in a near zero voltage.. Near zero volts times 20,000 amps is near zero energy - no energy inside a house to destroy appliances. How does one disconnect a refrigerator, GFCIs, smoke detectors (that must be working after every surge), clocks, dishwasher, air conditioner, etc? One does not. So where is protection? Disconnecting is a futile attempt when one ignores what Franklin demonstrated in 1752, what has been standard for over 100 years in facilities that cannot have damage, and what costs about $1 per protected appliance. To be blunt; no protector does protection. Effective protectors connect surges to what harmlessly absorbs hundreds of thousands of joules - single point earth ground. A protector is only as effective as its earth ground. Therefore only effective protectors have that always required and dedicated earth ground wire. Lightning rod is structure protection from lightning. Properly earthed 'whole house' protector is appliance protection from lightning (and other surges). This less expensive and well proven solution has always been that simple. |
#7
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Thunder
"KenK" wrote in message
... When I hear thunder, or I'm temporarily away from my XP Home computer and thunder is predicted, I turn the system and UPS off and unplug the modem telephone line. Overkill? Before I did this I lost the built-in modem to a nearby lightning strike (I assume). However most businesses and many other systems are left on durng storms evidently with no problems. No anxiety in users who have either (a) a surge protector on the household power supply or (b) lightning rods or similar grounds on metal chimneys, roofs, dishes etc. -- Don Phillipson Carlsbad Springs (Ottawa, Canada) |
#8
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Thunder
Don Phillipson wrote:
"KenK" wrote in message ... When I hear thunder, or I'm temporarily away from my XP Home computer and thunder is predicted, I turn the system and UPS off and unplug the modem telephone line. Overkill? Before I did this I lost the built-in modem to a nearby lightning strike (I assume). However most businesses and many other systems are left on durng storms evidently with no problems. No anxiety in users who have either (a) a surge protector on the household power supply or (b) lightning rods or similar grounds on metal chimneys, roofs, dishes etc. With the objective being in that case, if it is inevitable a high object is going to get hit, you're trying to deflect the energy if possible to a purpose-built structure. So the ideal situation, would be to have no "sharp pointed electrical devices" on your roof at all. Or, no metal roofing materials. Nothing to make a corona to form an ion channel. But if you must have things like that on the roof, then a lightning rod with a stout conductor to ground would help. Your objective is not to attract lightning as such. A rod with a sharp point on the top, can cause corona discharge. That can help construct an ion channel, to conduct the bolt, and have the bolt "prefer" to hit the rod, rather than surrounding items. If the rod had a smooth round metal ball of large diameter, then corona would be less likely to form, and the rod would not be as effective. That's why it has the point on the end. The conductor to ground should not be made of 30 gauge wire. It needs to be a decent piece of wire. Even whether it is stranded or solid wire might make a difference (mutual repulsion could cause a stranded wire to explode). And then the earth connection is important too. Areas of the country vary, as to how much junk shoved into the ground, is sufficient for conduction. In some areas, the materials in the ground make a poor conductor, requiring a fairly large structure (area-wise) might need to be used for grounding. Here, we might get away with a single rod shoved six feet into the ground. You need local advice as to what is sufficient where you live. If you do not offer a sufficient connection to ground, the lightning bolt you've "attracted" with the rod, as the energy is flowing down the wire, it can jump through the wall of the house, and follow any more enticing conductor it finds. With disastrous results. So this is not a toy to play with. If you're going to use rods, find someone who knows how to install them properly. As a kid, for a couple years I had a 100ft horizontal antenna for radio reception, in the back yard. To this day, I don't know why I'm still alive :-) We had lightning hit a tree in the back yard (or come close enough to it to split the trunk), but that was several years after I removed the antenna. Even back then, I was aware of the risk, but "not in technicolor", not realizing it could have started a fire, blown out a wall, or whatever. ******* I had an instructor at work, who happened to live in Florida. And he was a ham radio operator. He has a tower on the side of the house. The tower would have the usual grounding structure. But he also described how he protects the coax cable (feed) traveling up the tower. If the tower was hit, he'd be protected. But as energy flows down the tower, by transformer action, it makes a "1:1" copy of itself on the shield of the coax cable. He takes several large diameter winds of coax cable, into a coil. And holds it on the side of the house with nylon wraps. What happens then, is if induced lightning appears on the coax, it wants to flow into the house, following the cable. But the three or so coils of coax held to the side of the house in large loops, experience mutual repulsion. There is an explosion, and the coax coils are blown right off the side of the house. Leaving a large gap between the ends. The ham radio equipment could still be damaged. But the majority of the energy won't flow down the burnt remains of the coax at house level. So if there is a leader and return bolts, not all of them can follow the same path. The tower is likely to handle most of it. And the purpose of me telling that story, is to point out that any wire you use for your lightning rod, should not be coiled. It should be a straight run, right down to the grounding rod. As if you coil excess wire on purpose, it will function as an "interrupter" instead of as a "conductor". Paul |
#9
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Thunder
[Default] On Fri, 8 Jan 2016 16:07:57 +0700, in
microsoft.public.windowsxp.general JJ wrote: I agree with everyones. I unplug everything when I notice more frequent lighting and the thunder are getting louder. Personally, I don't have the confidence to trust a surge protector. IMO, if a lightning can jump from the clouds onto the ground, I don't think it's impossible for it to jump a few more millimeters or inches in a surge LOL. You make a good point. protector circuit. It can even blow up a thick wood if it gets in its way. Small chance, but it's not impossible. I just rather be safe than sorry. Chances are that it'll strike taller buildings or antennas. My suggestion is to make sure you have a properly installed lightning protection for the house. i.e. a rod at top of the highest part of the house When I first bought this house, I noted that it had a metal chimney (2 of them, one for the furnace and one for the metal fireplace) and I figured I'd attach a lightning rod to the top of the chimney, but I wanted some advice on grounding the fireplace box. I called the lightniing 800 number, but when they learned I wasn't in Florida, they seemed to lose interest. Heck, this was before the internet and the number was advertised in Maryland or I wouldn't know about it. I got distracted and since then I've figured the tall trees near my house provide protection, though I knew a woman with more tall trees than I have and lightning burned out her refrigerator, two phones and some things I've forgotten. connected to a cable that goes directly into the soil ground. This is not just for your house, but it's for everything in it. Power and phone lines are actually security risk in this matter. For the computer, unplugs everything, move the plugs and their wires (and you) as far away as possible from the power sockets (and phone sockets). Make sure the distance is farther than the distance between the power/phone socket and the soil ground. Would be great if your computer table has wheels so that you can move it too. http://stormhighway.com/surge_protectors_ups_lightning_protection_myth.php |
#10
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Thunder
On 1/8/2016 3:29 PM, westom wrote:
Excellent information on surges and surge protection is at: http://www.lightningsafety.com/nlsi_lhm/IEEE_Guide.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 (as everyone likely knows the IEEE is a major organization of electrical and electronic engineers). And also: http://pml.nist.gov/spd-anthology/fi...es_happen!.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 The IEEE surge guide is aimed at people with some technical background Many without surge protection talk in terms of 'blocking' or 'absorbing' a surge. Westom can't figure out how protection works. He believes it must be "blocking" or "absorbing". Both are wrong. How does that 2 cm part inside an adjacent (near zero) protector 'block' what three miles of sky could not? It doesn't. Of course it doesn't. Protectors do not work by "blocking" How do its hundreds of joules 'absorb' surges that are hundreds of thousands of joules? It doesn't. Of course not. Neither service panel or plug-in protectors work by "absorbing". (But both do absorb some energy in the process of protecting.) And the energy that can reach a plug-in protector is rather small. See another post. For over 100 years, the informed connected 20,000 amps to earth via a properly earthed 'whole house' protector Service panel protectors are a real good idea. But from the NIST surge guide: "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 [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable 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." Service panel protectors do not, by themselves, prevent high voltages from developing between power and phone/cable/... wires. The NIST surge guide suggests most equipment damage is from high voltage between power and signal wires. (plug-in protectors have all but no earth ground connection). Westom believes all protection must directly earth a surge, and can't figure out how plug-in protectors work. As the IEEE surge guide explains (starting page 30) plug in protectors do not work primarily by earthing surges. Earthing occurs elsewhere. Plug-in protectors work by limiting the voltage from each wire (power and signal) to the ground at the protector. he voltage between the wires going to the protected equipment is safe for the protected equipment. If using a plug-in protector all interconnected equipment needs to be connected to the same protector. External connections, like coax also must go through the protector. To limit the voltage from each wire to the ground at the protector all wires must go through the protector. A protector is only as effective as its earth ground. Therefore only effective protectors have that always required and dedicated earth ground wire. Flying planes are crashing every day when they are hit by lightning. For real science read the IEEE and NIST surge guides. Excellent information from reliable sources. And both guides say plug-in protectors are effective. |
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Thunder
On 1/8/2016 3:07 AM, JJ wrote:
Personally, I don't have the confidence to trust a surge protector. IMO, if a lightning can jump from the clouds onto the ground, I don't think it's impossible for it to jump a few more millimeters or inches in a surge protector circuit. The author of the NIST surge guide (cited in another post) looked at energy that could reach a plug-in protector. He found the maximum surge on incoming power wires with any reasonable probability of occurring is 10,000A per wire. That is with a 100,000A lightning strike to the power wires at an adjacent utility pole in typical urban overhead distribution. Only 5% of strikes are stronger, and the strike is extremely close. (Service panel protectors with much higher ratings are readily available.) Using that surge and branch circuits 10m and longer, the maximum energy that made it to the MOV in a plug-in protector was a surprisingly small 35 joules. In 13 of 15 cases it was 1 joule or less. Plug-in protectors with much higher ratings are readily available. There are a couple reasons the energy is so low. One is that at about 6,000V there is arc over from the service panel busbars to the enclosure (US). Since the enclosure is connected to the earthing system that dumps most of the energy to earth. Since the neutral is bonded to the ground/enclosure (US) that also limits the exposure inside the house. The second reason is that lightning is a very short event. That means that the surge current components are relatively high frequency (relative to 60Hz). That means the inductance of the wires is much more important than the resistance. You simply can't have high surge currents. Some plug-in protectors have protected equipment warranties. They can have warranties because the exposure is far lower than we imagine it is. My suggestion is to make sure you have a properly installed lightning protection for the house. i.e. a rod at top of the highest part of the house connected to a cable that goes directly into the soil ground. This is not just for your house, but it's for everything in it. The problem of conductor impedance is also a problem for rod down-conductors. Resistance goes down rapidly with larger diameter wire, but inductance is not reduced nearly as fast. As a result the potential at the rods can be far higher than the potential at the earth connection. Metal within 6 ft of the lighting rod system may have to be bonded to the system. If it isn't, there can be a side flash between them. Also, if an "average" lightning strike of 20,000A is earthed to a pretty good 5 ohm-to-earth earthing system, the earth connection will be 100,000V from 'absolute' earth potential. (There can be arcing along the surface of the earth near the connection.) In the US, the lightning rod earthing system must be bonded to the power earthing system. You want everything to float up to the same potential. http://stormhighway.com/surge_protectors_ups_lightning_protection_myth.php Has some major wrong information. See above. |
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Thunder
On 1/9/2016 5:50 AM, Paul wrote:
With the objective being in that case, if it is inevitable a high object is going to get hit, you're trying to deflect the energy if possible to a purpose-built structure. The electrical charge in lightning descends in a series steps (a stepped leader). When it gets low enough, it strikes whatever is nearest. That is usually the highest, but not necessarily. Lightning can strike the side of a house. The final striking distance is longer for stronger strikes - weaker strikes can hit the side easier than strong strikes A rod with a sharp point on the top, can cause corona discharge. That can help construct an ion channel, to conduct the bolt, and have the bolt "prefer" to hit the rod, rather than surrounding items. If the rod had a smooth round metal ball of large diameter, then corona would be less likely to form, and the rod would not be as effective. That's why it has the point on the end. Seems reasonable. But the limited research that I have seen indicates a rounded end is more likely to be hit. If you had corona discharge at the rod-end, that can form a charge-cloud that hides the rod. Rods get hit because they are designed to be closer. The conductor to ground should not be made of 30 gauge wire. It needs to be a decent piece of wire. Even whether it is stranded or solid wire might make a difference (mutual repulsion could cause a stranded wire to explode). Every down-conductor I have seen was stranded. (else it would be very hard to bend). |
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Thunder
On Sat, 9 Jan 2016 13:37:43 -0600, bud-- wrote:
Every down-conductor I have seen was stranded. (else it would be very hard to bend). The main reason for that is high frequency current actually travels down the skin of the wire so that braided stranding offers a lot more area to carry the leading edge of the shot. |
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Thunder
On Saturday, January 9, 2016 at 7:17:11 PM UTC-5, wrote:
The main reason for that is high frequency current actually travels down the skin of the wire so that braided stranding offers a lot more area to carry the leading edge of the shot. Braided to lower impedance to earth. Since a protector is only as effective as its earth ground. That means impedance (inductance) as low as is possible. However braided cable is no longer recommended even in Mil-Std installations. Because braided cable corrodes faster. Effective protection even from direct lightning strikes must remains functional for decades. Protection is defined by that connection and its earthing electrodes. A misrepresented citations says what defines protection. Not any protector.. But if anyone learns this, then his employer will suffer diminished profits. Quote:
Quote:
Quote:
Braided wire was once commonly used to make effective 'whole house' protectors better. Because protection is always about making a low impedance connection (ie more surface area means lower inductance and impedance). Solid copper wire is now preferred so that what is critical to surge protection (earthing and its connection) is not corrupted or compromised by corrosion and weather. In every case, protection is defined by quality of and a (low impedance) connection to single point earth ground. That does not sell undersized and extremely profitable plug-in protectors. Protection has always been about where hundreds of thousands of joules dissipate. A protector is only as effective as its earth ground. Critical is that low impedance connection. NIST guide, that shows why plug-in protector need a 'whole house' solution, makes same recommendations. NIST guide says what a protector must do: Quote:
Effective protection means a surge is not anywhere inside - if earthed (a low impedance connection) by a proven, much less expensive, and properly earthed 'whole house' solution. Because the earthing connection is critical, braided wire was once often used. Then no surge anywhere inside a house means no 8000 volt damage to a TV made possible by a nearby plug-in protector. Key to that is connecting a surge low impedance to earth. So that a destructive current is not inside the house. |
#15
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Thunder
On Saturday, January 9, 2016 at 7:17:11 PM UTC-5, wrote:
On Saturday, January 9, 2016 at 7:17:11 PM UTC-5, wrote: The main reason for that is high frequency current actually travels down the skin of the wire so that braided stranding offers a lot more area to carry the leading edge of the shot. Braided to lower impedance to earth. Since a protector is only as effective as its earth ground. That means impedance (inductance) as low as is possible. However braided cable is no longer recommended even in Mil-Std installations. Because braided cable corrodes faster. Effective protection even from direct lightning strikes must remains functional for decades. Protection is defined by that connection and its earthing electrodes. A misrepresented citations says what defines protection. Not any protector.. But if anyone learns this, then his employer will suffer diminished profits. An effective, low-impedance ground path is critical for the successful operation of an SPD [Surge Protection Device]. High surge currents impinging on a power distribution system having a relatively high grounding resistance can create enormous ground potential rises, resulting in damage. Therefore, an evaluation of the service entrance grounding system at the time of the SPD installation is very important. True for all protectors. A protector is only as effective as its earth ground. Citation says more about what is most important: To achieve optimum overvoltage protection, ... These large inductive voltage drops are added to the inherent limiting voltage of the SPD, raising the effective limiting voltage at the service equipment terminals. The inductance of the wire is the determining factor rather than the resistance of the wire. The inductance is a function of the length and the loop area of the circuit including the SPD. Protectors (ie plug-in type) too far from earth provide worst protection. The numbers: For 20 inch (50 cm) leads, the extra voltage from the inductance of the leads is almost 600 V for the 10 kA impulse, almost doubling the limiting voltage of the protector itself. One of the main functions of the service entrance SPD is to reduce the surge current reaching any downstream protectors Impedance is why a wire from protector to what absorbs energy must be so short (ie less than 10 feet - as short as is practicable). To even protect downstream (plug-in) protectors. Plug-in protectors, without that low impedance connection, do not claim to protect from typically destructive surges. Even refuse to discuss it to protect sales. Proven and properly earthed 'whole house' protection is essential to even protect downstream (plug-in, point of connection) protectors. Braided wire was once commonly used to make effective 'whole house' protectors better. Because protection is always about making a low impedance connection (ie more surface area means lower inductance and impedance). Solid copper wire is now preferred so that what is critical to surge protection (earthing and its connection) is not corrupted or compromised by corrosion and weather. In every case, protection is defined by quality of and a (low impedance) connection to single point earth ground. That does not sell undersized and extremely profitable plug-in protectors. Protection has always been about where hundreds of thousands of joules dissipate. A protector is only as effective as its earth ground. Critical is that low impedance connection. NIST guide, that shows why plug-in protector need a 'whole house' solution, makes same recommendations. NIST guide says what a protector must do: 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. By ignoring facts in his own citation, he hopes all will buy protectors that magically suppress or "arrest" a surge. NIST guide even shows, on Page 33 (Adobe page 42) figure 8, what happens when a protector is too close to appliances and too far from earth ground. It must earth that surge somewhere. So it connects a surge to earth 8000 volts destructively via a nearby TV. Effective protection means a surge is not anywhere inside - if earthed (a low impedance connection) by a proven, much less expensive, and properly earthed 'whole house' solution. Because the earthing connection is critical, braided wire was once often used. No surge anywhere inside a house means no 8000 volt damage to a TV made possible by a nearby plug-in protector. Key to that is connecting a surge low impedance to earth. So that a destructive current is not inside the house. That low impedance wire may be braided or solid coppper. But it must be short. |
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