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Post by jbrunwa on Jul 25, 2022 12:36:55 GMT -5
I’ve had two MOV failures in surge suppressor strips. As KeithL says, both were pretty spectacular failures with significant smoke and charring of the enclosure. I couldn’t buy a robust enclosure and a MOV for the price of a surge strip with one included (economy of scale at work). But don’t keep loose papers or other combustibles in close proximity to your surge strip! I gave up on MOV a few years ago. I now use only ZeroSurge series surge protection devices. They say they have never had a failure. I use the 2 outlet model and plug a plain outlet strip into it to provide the number of outlets I require. |
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Post by leonski on Jul 25, 2022 14:26:50 GMT -5
Just a note for anyone considering doing anything DIY with MOVs. Remember that an MOV does NOT "magically eat the surge".... When the MOV "activates" it simply short circuits the surge to ground for a split second. And, in order to do this, the ground connection it's connected to must be able to handle that current. Therefore it is critical that the other end of that MOV have a REALLY SOLID connection to a REALLY SOLID ground. The protection you get from the MOV is only as good as the ground it is connected to.(Remember that what you call "ground" is simply a wire connected to "ground".) If your ground is not solid... For example if you use a cute little ground terminal... Or a thin ground wire... Or if the ground on your circuit breaker panel is weak... Then your GROUND may jump up to a VERY DANGEROUSLY HIGH potential... (You can actually get a dangerous surge in the ground connection itself.) So it's very important that you make sure your ground connections are tight and properly maintained. (That's one of the benefits of series-mode protectors... they don't rely on being able to safely dump lots of current to ground.) And, yes, as Leonski said, when an MOV does fail, they tend to explode into little burnt pieces... Often to the accompaniment of quite a bit of smoke and even a risk of actual fire... (MOVs are considered to pose a fire risk - so they should always be used in at least a fire-resistant enclosure... ) Yes.....Anyone buying into MOV should be aware it is is sacrificial device. Big enough surge and it's plastered all over the inside of the enclosure. But for sub-critical hits? They'll last quite a while. Here in SoCal, for example, we don't have much in the line of big zaps, except maybe up in the mountains or out in the deserts..... For those actually interested in how they work? Look at the link I provided for a Good, simple explanation. And since they are 'commodity cheap'? You may be able to use them in a DIY fashion? CHECK Local Building / Electrical Codes. My house has a long (10 feet?) Copper Rod bonded to the ground of my electrical system..... While of course, with point of use surge protection, you are limitied to the size of the ground wire. Again? check building / electrical codes, but in some cases I'm not certain the Ground needs to be the same size as the Hot / Neutral. It can be one gauge smaller. So? 12ga wire and 14ga ground. CHECK YOUR LOCAL code or in some cases the NEC....National Electric Code. Keith has a point, though. What we count on is that a strike be far enough away to 'fan out' thru the grid and Zap YOU less. A direct or next door strike? Sorry about that! Water is funny stuff. The maximum resistivity of water is 18 Megaohm. I'm not certain of the measuring conditions. We had rinse baths that would rinse product until the water reached a certian resistivity....maybe 10meg or so, than switch to 'dry' mode. A special cell was in the drain stream and always fully immersed. That was the measureing point. |
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KeithL
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Post by KeithL on Jul 25, 2022 15:02:40 GMT -5
I have a pair of very similar units made by BrickWall...
(Although, to be fair, I don't think I've ever experienced a truly major surge either.)
I’ve had two MOV failures in surge suppressor strips. As KeithL says, both were pretty spectacular failures with significant smoke and charring of the enclosure. I couldn’t buy a robust enclosure and a MOV for the price of a surge strip with one included (economy of scale at work). But don’t keep loose papers or other combustibles in close proximity to your surge strip! I gave up on MOV a few years ago. I now use only ZeroSurge series surge protection devices. They say they have never had a failure. I use the 2 outlet model and plug a plain outlet strip into it to provide the number of outlets I require. |
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Post by leonski on Jul 25, 2022 15:18:28 GMT -5
Good information. If I EVER saw lightning other than 'between clouds' or looking like a Fluorescent lamp that wouldn't start? I'd consider. My house backs up to a hill which provides a little protction, but I"m not in the protection cone of 45 degrees.... BTW? If you thought you needed this here in SoCal? 3x the national average would be where it'd start. Followed by who knows WHAT nonsense from the building department (another 1200$ in permits, fees and inspections......) while copper would suddenly be as precious as Rhodium..... |
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KeithL
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Post by KeithL on Jul 25, 2022 15:24:18 GMT -5
It's also worth mentioning that a lightning rod system protects your house from "a direct physical hit"... either on the structure or the wiring inside it... (or the plumbing if you have metal plumbing).
A lightning rod DOES NOT protect you from a surge caused by a hit on the power grid, or the transformer on your pole, or even on the power drop line from the pole to your house.
And, unless you live in that creepy old mansion on the top of the hill, if your AREA is prone to strikes... Then there is a lot of risk that the grid NEAR your house will be what gets hit... And the result could be a major surge through the grid...
In most places the power grid itself is protected against really major surges... But that type of protection could easily allow through a short surge of "only two or three thousand volts"...
According to BrickWall "according to the IEEE the largest transient the interior of a building should experience is around 6000v".... And this is what their are tested to withstand... (I believe the other series-mode surge suppressors carry similar ratings.)
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Post by leonski on Jul 25, 2022 15:40:22 GMT -5
It's also worth mentioning that a lightning rod system protects your house from "a direct physical hit"... either on the structure or the wiring inside it... (or the plumbing if you have metal plumbing).
A lightning rod DOES NOT protect you from a surge caused by a hit on the power grid, or the transformer on your pole, or even on the power drop line from the pole to your house.
And, unless you live in that creepy old mansion on the top of the hill, if your AREA is prone to strikes... Then there is a lot of risk that the grid NEAR your house will be what gets hit... And the result could be a major surge through the grid...
In most places the power grid itself is protected against really major surges... But that type of protection could easily allow through a short surge of "only two or three thousand volts"...
According to BrickWall "according to the IEEE the largest transient the interior of a building should experience is around 6000v".... And this is what their are tested to withstand... (I believe the other series-mode surge suppressors carry similar ratings.)
I just read the exact same 6000v number. Testing / specs are tought with either Zero or Brick protection. Someone noted that Brickwall is a Liscencee of ZeroSurge...... Any whole house product or just point of use? |
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Post by DavidR on Jul 25, 2022 16:51:54 GMT -5
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Post by Boomzilla on Jul 25, 2022 17:07:13 GMT -5
In the house we owned 30 years ago, a storm rolled through one night and the power went out. Despite having no electricity, every fluorescent light in the house was glowing brighter than if they’d been powered, and the TV screen was similarly glowing. It was eerie!
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Post by housetech on Jul 25, 2022 17:19:57 GMT -5
Double thumbs up for brick wall surge protectors.
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Post by leonski on Jul 25, 2022 18:56:21 GMT -5
In the house we owned 30 years ago, a storm rolled through one night and the power went out. Despite having no electricity, every fluorescent light in the house was glowing brighter than if they’d been powered, and the TV screen was similarly glowing. It was eerie! Shades of Nikola Tesla! |
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Post by Boomzilla on Jul 25, 2022 19:09:26 GMT -5
Double thumbs up for brick wall surge protectors. No surge protector would have prevented this. It was not from the power grid - it was static electricity. The lights and television were turned off, but there was sufficient static in the atmosphere to cause them to glow. |
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Post by leonski on Jul 25, 2022 20:56:28 GMT -5
Tesla (Nikola) was a HUGE fan of what we'd identify as 'broadcast power'. His lab was located in Colorado Springs, which might be the 'lightning capitol' of the United States. The experiments undertaken there were successful and he burned out the largest generator west of the Mississippi.... Today, we know about the Schuman Resonance, which I suspect Tesla would have 'fed' in order to create a dense enough field to power appliances worldwide. The Wardenclyff Tower was early 20th century. His Colorado Springs experiments were immediately PRIOR to the construction of the tower. www.nasa.gov/mission_pages/sunearth/news/gallery/schumann-resonance.htmlBoom? Your house is obviously haunted by the spirit of Tesla...... |
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Post by Boomzilla on Jul 25, 2022 21:52:40 GMT -5
I’d have preferred the spirit of Sofia Vergara… but it was what it was!  |
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KeithL
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Post by KeithL on Jul 26, 2022 9:07:51 GMT -5
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KeithL
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Post by KeithL on Jul 26, 2022 9:25:57 GMT -5
That's pure electric field power... With the ground at ground, and the clouds at as much as several million volts, there's enough field strength across the length of the bulb to light it. You're basically inside a charged capacitor; the ground is one plate, the cloud is the other, and the air is the dielectric ... (And, when the air ionizes, and that dielectric "breaks down", you have a lightning strike... which is a place you do not want to be standing.) Supposedly you can create a similar effect simply by holding up a fluorescent bulb if you happen to be standing under a high-voltage power line. In that case the field strength is continuous - and well within the ability of the air to maintain its insulation integrity. A very high-voltage line... not the 6kV lines that run through the small poles in front of your house. (It requires a field strength of several thousand volts across the length of the bulb to light it up at all brightly.) In the house we owned 30 years ago, a storm rolled through one night and the power went out. Despite having no electricity, every fluorescent light in the house was glowing brighter than if they’d been powered, and the TV screen was similarly glowing. It was eerie! |
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Post by Boomzilla on Jul 26, 2022 10:41:25 GMT -5
Yep - we had 50,000V feeders at the plant and could do that trick.
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Post by Boomzilla on Jul 31, 2022 6:43:39 GMT -5
Back in 1976, I got my first well-paying job. In anticipation of that job, I went by the local Nissan dealer knowing that I'd need a reliable car to get to work. In my usual worn jeans & t-shirt, I must have wandered around the dealership for 30 minutes, and not a single salesman approached me. Well, I got the job and a week or two later returned to the Nissan dealership. This time, the moment I walked in, no fewer than FOUR salesmen descended on me asking if I needed help. After selecting a car, I told the salesman of my experience the previous visit, explained that I was dressed identically, and asked what attracted the salesmens' attention to me this time. He said "it's the glasses." Only guys who work in plants wear that style of safety glasses, and anyone who works in a plant can afford one of these cars.
I never forgot that experience, and when I opened my consulting business, began wearing much better clothes, shoes, and watches to advertise "success" to my potential clients. Seemed to work, and validates the old saw "clothes make the man."
Now that I'm older, I have also noticed that manners, courtesy, and a professional demeanor can get me into a lot of places where first impressions can't.
Boomzilla
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Post by leonski on Aug 2, 2022 20:53:30 GMT -5
No values for inductor OR the caps. And I'm unclear on just what a 'snubber' IS? Which is not to say I've never been snubbed..... |
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Post by garbulky on Aug 2, 2022 22:43:35 GMT -5
Back in 1976, I got my first well-paying job. In anticipation of that job, I went by the local Nissan dealer knowing that I'd need a reliable car to get to work. In my usual worn jeans & t-shirt, I must have wandered around the dealership for 30 minutes, and not a single salesman approached me. Well, I got the job and a week or two later returned to the Nissan dealership. This time, the moment I walked in, no fewer than FOUR salesmen descended on me asking if I needed help. After selecting a car, I told the salesman of my experience the previous visit, explained that I was dressed identically, and asked what attracted the salesmens' attention to me this time. He said "it's the glasses." Only guys who work in plants wear that style of safety glasses, and anyone who works in a plant can afford one of these cars. I never forgot that experience, and when I opened my consulting business, began wearing much better clothes, shoes, and watches to advertise "success" to my potential clients. Seemed to work, and validates the old saw "clothes make the man." Now that I'm older, I have also noticed that manners, courtesy, and a professional demeanor can get me into a lot of places where first impressions can't. Boomzilla B'zilla is well received everywhere he goes! He's such a nice guy. |
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Post by Boomzilla on Aug 2, 2022 23:03:30 GMT -5
B'zilla is well received everywhere he goes! He's such a nice guy. Did someone forget to tell my wife? LOL |
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