Here's a very good document on home protection written for the non-electrically inclined-
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Pay particular attention to the section on GPR, there's a lot of people in the industry who, while they may know about it "intellectually", don't really think about it enough. :(
Suppressors don't just protect against lightening but also against transient spikes on the power lines induced by heavy equipment etc.
How much protection you get depends on how much money you spend. The cheaper MOV "little black box" units that Mr. Holme's electrician is so in love with (he does do neat wiring, though :)) are good for the occasional spike, if you live in an area prone to lightening & you own a lot of $$$ electronics you might want fork out for an industrial strength unit-
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but figure on ~$1000 for a top of the line one with SASD devices that will stand up to the abuse.
cavelamb wrote in news:crqdnXdLqtofmDjWnZ2dnUVZ snipped-for-privacy@earthlink.com:
often,the "protected" parts are faster to blow than the protection device.
there are specs on how fast such protection has to operate. It's a few nanoseconds. also,how much energy)in joules) that it must be able to shunt or absorb. Often,the strike is way more than the device can tolerate.
I've seen MOVs that has absorbed a lightning strike and blew apart,yet the power supply itself survived.All it needed was a new fuse and cleaning the blown MOV's metal deposits off the PCB.
No, it isn't. A "true" GPS, be it motor-gen or otherwise, is not the genuine animal unless it's output is being generated constantly whether commercial power is present or not. A motor-gen UPS would not be fit the true GPS definition unless the generator ran constantly from its source of power, battery or commercial. In the "true" GPS, switching is implemented only in the event of primary power failure; and then only to interrupt or restore primary power to the batteries charging component.
Bob Swinney
"chicken UPS's"
installations, both on PBX
I recall the batts
Hi, In my working days in radio telcomm. UPS was composed of battery bank, motor-generator set and control(switching) unit. I don't recall we ever suffered radio link outage. This is true UPS.
Either you buy a protector that will somehow absorb all that energy. Or you buy protectors based upon how it was done even 100 years ago. Protection is always about where energy dissipated. Either that energy remains outside the building. Or that energy is inside hunting for earth ground destructively via appliances. Adjacent protectors simply give surges even more potentially destructive paths through adjacent appliances.
An effective surge protector means even the protector remains functional. A minimal 'whole house' protector starts at 50,000 amps. Direct lightning strikes are typically 20,000 amps. Yes, the protector must be sized to even earth direct lightning strikes and remain functional. And that means the connection to earth must be additional requirements - short ('less than 10 feet) to earth, no sharp wire bends, no splices. all protectors meet at (again 'less than
10 feet to') the single point earth ground, ground wires separated from other non-ground wires, not inside metallic conduit, etc.
Protection is always about where energy dissipates. If those hundreds of thousands of joules dissipate in earth, then no damage. This is how it was done even 100 years ago.
But somehow a magic box next to the appliance will absorb all those joules? Always view the tech specs. Plug-in protectors rates at hundreds of joules will somehow make hundreds of thousands just disappear? That is what they claim. In analysis, we even traced surges earthed destructive through a network of powered off computers because the surge was permitted inside the building. And because a surge on the black (hot) wire was connected directly to the motherboard by the protector. The protector bypassed protection inside the computer's power supply.
Telcos do not waste money on protectors adjacent to electronics. That switching center must never suffer damage. A switching center, connected to overhead wires all over town, may suffer 100 surges with each thunderstorm - and no damage. Why? Each protector connects short to the single point earth ground. And the protector is up to 50 meters separated from electronics. That separation increases protection.
No protector is protection. None. The only effective protectors make that short connection to single point earth ground. Ineffective protectors (a $3 power strip with some ten cent protector parts selling for $25 or $150) are profit centers. The NIST (US government research agency) discusses those ineffective protectors by describing what every protector must do:
by diverting the
grounding is
The NIST describes plug-in protectors as "useless". Obviously. It does not even claim protection in its numeric specs. Find those spec numbers that list each type of surge and protection from that surge? No plug-in protector makes protection claims. They are a profit center.
Protection is always about where energy dissipates. IOW why facilities with effective protection both meet and exceed post 1990 National Electrical code. Where does energy dissipate? A protector is only as effective as its earth ground - which no plug-in protector has and therefore will not discuss. Effective 'whole house' protectors come from General Electric, Keison, Intermatic, Siemens, Square D, and Leviton. An effective Cutler-Hammer solution sells in Lowes and Home Depot for less than $50.
How bout a surge from downed power lines? Ours got knocked down from ice on trees falling on the main lines into the house 4am Christmas eve. Started a fire (12" flames) on the Belkin UL approved spike/ surge protector right next to the christmas tree & plasma TV! Could never get an answer as to why this happened. Knocked out a couple other surge strips including a plug in CO2 detector. Thank god thats all that happened.
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Must be something to do with the end of the power- where it dissipates ?
That isn't correct. The main function of a surge protector is to shunt the current to ground. In doing so, SOME of the power is converted to heat as it passes through because the MOVs are not perfect conductors and do have some small resistance.
All of the good whole house surge protectors that I have seen have indicator lights that show if they are still functioning or not. Some also have audible alarms to signal that they have failed, or relay contacts that can be sent to a remote alarm system, etc.
Well, we all knew this was coming. Mention surge protector, and like a bolt of lightning from the sky, here comes WTom.
So far, I would mostly agree. Except the part about a direct lightning strike. A direct lightning strike is mostly a red herring, because even if the lightning bolt hit the service cable near the building, it's highly unlikely that the path of all or even most of the lightning is going to be through the service wire and into the surge protector. Far more likely, it will arc with most of the energy finding ground outside the building before it ever gets to the surge protector at the panel or meter.
Here;s where Tom likes to start arguing against strawmans and the rant about plug-in surge protectors begins. The actual question was about a whole house surge protector.
Total nonsense. Every line card on a telco switch has surge protection right on the card where it connects to the incoming line. Much like if you take apart an analog modem, you will almost always find MOVs or similar components there.
In fact, just like the IEEE recommends, the telco uses a tiered approach. Yes, they have surge protection where the line enters the building. But they also have it on the line cards. Months ago I even found you semiconductors designed and marketed for telcos that go on the linecards, complete with the application notes. Yet, here we go again.
Please provide us a link to NIST or any other credible source that says plug-in protectors are ineffective as part of a protection plan. You've been asked that here for years and we have yet to see the link.
will work by diverting the
e useless if grounding is
And here comes the list again. What Tom won't tell you is that of those companies on his list of real effective and responsible manufacturers, most of them also sell plug-in surge protectors. They recommend using them as part of a tiered strategy.
As for the HD solution for less than $50, that doesn't square with your criteria of needing a minimum of 50,000 amps, because they have no such product available at HD.
The best advice was already provided. That was the link to the IEEE guide on surge protection.
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Everyone can read what respected peer-reviewed engineers recommend. And I can tell you this. They don't say plug-ins are ineffective. Read chapters 5 and 6. Instead, they show them being used as part of a tiered strategy. You put whole house protection at the meter or panel. Then you use plug-ins that route all power and signal through them, to further protect key equipment, eg, TVs, PCs, etc.
Hopefully everyone here either has him filtered out, or is intelligent enough to ignore him completely. Debating him is a fools errand.
His use of usenet consists of scanning for threads about surges, lightning and power strips. He's been spewing his nonsense for years. Occasionally he manages to fool someone and they start conversing with him, or thinking that he is on to something. The only thing he is on to is some sort of mental illness. Either that, or he is one of the greatest trolls of all time.
Ferrite rings are for EMI, so the buzz in the box stays there and not in your radio or stereo. Switching power supplies can generate a whole lot of hash and that's the type that's gradually replacing the old-syle wall warts. The ring is acting as a choke for RF, also generated by the computer itself. Different deal than surge protection, but also needed these days.
Look up "surgistor" or MOV, that's what's in those surge protectors. They're rated in joules, the amount of energy they can pass. The higher, the better, and more costly they get. The better surge protector strips will say how much energy they can handle on the package. I assume the panel versions do the same. What none of the ad copy says is that MOVs have a distinct lifespan. They WILL wear out after snubbing "x" number of spikes and become useless. Some of the power strip units tie the neon switch light to the MOVs. If no light when switched on, the MOVs have expired and it's time for a new strip. But nobody tells the consumer about it. So there's a whole lot of dead protectors out there that are just power strips now. Usually there's MOVs between ground and each supply wire and between the supply wires. Not rocket science.
As far as lightning protection, they'll do part of that, up to the energy rating. Which is why you need the tiered approach. Arrestors on the line in, surge protectors on the panel and on each high-value electronic item. My sister is always getting hits, they blow the phones off the walls, but since she's gotten decent surge protectors, those get fried instead of the computer or video equipment. They have to be replaced, but she gets the sort with insurance attached, so not that costly.
There are other approaches to surge and spike protection, an MG set is pretty much immune to any such up to direct lightning strikes. A ferro-resonant transformer used to be a big part of the innards of one line of power conditioners, pretty much immune to spikes, but the transformer itself was noisier than a whole switch yard. Had one in a corner of the shop for a mini-computer, had to go outside to talk to anyone. None of those will snub spikes on LAN, phone or video cables, for that you have to go to power strips with built-in protection or stand-alones.
I posted links to photos of telco cards with rows of MOVs, yet he claims they don't exist. He is just a brain dead troll like Cliff, and The_Mangled_Toad.
While I was staying in a motel in Southington, CT an empty room burned. Smoke detector started the fire. Melted & dripped flaming plastic on the bed ....
(Had central wiring back to the office & was poorly installed.)
Lightning strikes can be far larger than 50,000A (but low percentage). But a strike to a power line has multiple paths to earth. Investigations have shown the largest lightning-caused surge with any reasonable probability of occurring is 10,000A on an incoming power wire. The
50,000A suppressor rating can handle that. High ratings give long life.
The best information on surges and surge protection is in a guide from the IEEE at:
(also posted by Howard and trader) and a simpler guide from the NIST at:
Neither service panel or plug-in suppressors can reliably handle crossed power lines. MOVs which can handle 10,000A for maybe 100 microseconds are rapidly burned out by longer duration events. (These events are probably the major cause of catastrophic MOV failures.)
I would not make my own suppressor attached to power lines (other than fuse protected MOVs in equipment).
Poor w has to warp a thread about service panel suppressors to his favorite topic - plug-in suppressors. Trying to not repeat traders nice reply....
François Martzloff was the surge guru at the NIST and wrote the NIST guide. He also wrote numerous published technical papers. One paper looked at the energy absorbed in a MOV on a branch circuit. It was surprisingly small - 35 Joules max. In 13 of 15 cases it was 1 Joule or less. That was with up to 10,000A coming in on the service wire. There are a couple of reasons for that - I could elaborate if anyone is interested.
Plug-in suppressors are only a "magic box" to w because he refuses to understand how they work - clearly explained in the IEEE guide starting pdf page 40. They work by CLAMPING (limiting) 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 absorbing). The guide explains earthing occurs elsewhere.
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). It is likely that much of equipment damage is from high voltages between power and signal wires. This is illustrated in the IEEE guide example starting pdf page 40.
A service panel suppressor can not limit the voltage between power and signal wires. To do that, there has to be a *short* ground wire from the telephone entrance protector to the earthing system near the power service. Also for the cable entrance ground block (and dish....) With a large surge current to earth, the "ground" at the building can rise thousands of volts above "absolute ground". Much of the protection is that power and phone and cable wires rise together. If short ground wires can not be used (as in the IEEE guide example) the guide says "the only effective way of protecting the equipment is to use a multiport [plug-in] protector."
For similar reasons, all protected equipment that is interconnected needs to be connected to the same plug-in 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.
What does the NIST guide really say about plug-in suppressors? They are "the easiest solution". And "one effective solution is to have the consumer install" a multiport plug-in suppressor.
The required statement of religious belief in earthing. Why aren't airplanes crashing daily when they get hit by lightning (or do they drag an earthing chain)?
Often asked and never answered - simple questions:
- 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 does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor?
- Why does the IEEE guide say for distant service points "the only effective way of protecting the equipment is to use a multiport [plug-in] protector"?
- Why do your favorite manufacturers make plug-in suppressors?
- Why does favorite manufacturer SquareD say (for their service panel suppressor) "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use"?
And why can't you find a source that agrees with you that plug-in suppressors are not effective?
For real science read the IEEE and NIST guides . Both say plug-in suppressors are effective.
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