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Do You Unplug For Thunderstorms?
- Thread starter ncridgerunner
- Start date
CyberGus
Not Just a Member
As long as you don't have a Flux Capacitor, you should be good
legendsk
Member
Most of the surge suppressors for sale will reduce or stop small surges. But they are about like laying a penny on a railroad track with the hope of stopping a train. I do watch the weather a little to decide for scheduling outdoor activities. When I see a storm moving in that has some lightning I will make it a point to unplug the Tesla, (and leave the wall connector plugged in), because the repair cost of the Tesla is an order of magnitude or 2 more than my old computer, tv, etc. The neighbors have had frequent damage to their electronics, in some cases about everything in the house, but I have only had a couple of LED lamp failures.
And I'm going to double up on this one.
There's this general idea around serious surge protection: First you got the input power feed; then, you have a filter, usually with chokes and possibly capacitors; and then you have your voltage limiting devices, like MOVs or TVS diodes. The filter is jiggered to be low-pass: That is, low frequency stuff (like, say, 50Hz/60Hz) flies on through with no attenutation. But at high frequencies, say, something above a kHz or 20, the filter will have serious attenuation.
The general way this works is as follows: Say one has a nearby lightning strike with 1.5us to 20us rise times. This hits the filter. If all the filter has is inductors (not unusual), this will fly right on through; but, when one hits the MOV, it does its turn-on and low-impedance trick.
We now have a low impedance to ground, neutral, or whatever; and current starts to flow through ye inductor. Inductors hate rapid changes in current, so all the voltage drop is across the inductor. Ta-da! The inductor(s) has/have, effectively, isolated the house from whatever madness is going on with city power. And that's how one keeps all the electronics on the other side of the surge protection from letting the smoke out.
Extra credit can be achieved by:
- placing small, but high voltage capacitors across the MOVs and/or in front of the inductors on city power.
- Placing spark gaps on the city power side of the filter. It won't change rise times too much, but it will shunt a goodly amount of the applied energy to ground.
And this is where things go somewhat off the rails when one talks about a whole-house surge protector. That surge protector box that's plugged into a wall outlet? The wire gauge has to be big enough to handle 15A or so. That's not teensy-tiny wire. That means that, to get the 1uH to 15uH inductance one needs to do the job, the inductor has to be Physically Large. It'll be small enough to fit in the Home Depot special, sure.
But now lets talk about somebody who's got a 200A panel. Um. That's BIG wire. Roughly the same number of turns, but the whole shooting match is not going to fit in a 3"x3"x3" box. Since one needs at least two, and probably three of these inductors. And the MOVs have to be bigger since, well, we're talking more energy anyway.
So: Those cheapie ones from Home Depot are cool, may do something for the occasional surge since the MOVs will be present; but I'd expect that MOVs (which, remember, do have limited lifetimes) would fail after a time. The one you want probably costs at least a couple hundred bucks and requires a real electrician to put it in, probably (not sure about this) after the meter but before the breaker box.
Again: One goes to this kind of extreme when one's a farmer on the flats; or the poster somewhere earlier in this thread whose garage or whatever was situated on a ridge and was subject to some serious lightning energy. Most of us don't need to sweat it.
But I hate the idea of that Home Depot special. My impression is that those look great, but won't do anything for you (except, perhaps, explode) when a real lightning bolt strikes nearby.
(And that last bit: Yes, I've had to personally contend with blown-up gear, smoke, removed parts, and burned-out circuit boards that was due to lightning a few times. Usually it's been due to seriously improper grounding in the field.)
NewbyMaybe
Newby1Kenowby
The general rule if there's smoke after the strike then you're screwed, no one has figured out how to get the smoke back into those parts.
Chewy13
https://ts.la/nick670348
Well I like to lie to myself that my Siemens FS140 does something to protect my gear
Interesting. I've read the data sheet.Well I like to lie to myself that my Siemens FS140 does something to protect my gear
Clearly, what's in there is a MOV/TVS diode combo. Cute that they say it can respond in 1 ns. That implies that it's a combo of TVS diodes (silicon, fast reacting, but power dissipation is limited) and MOVs (bulk material, capable of a fair amount of instantaneous power dissipation, but slower reacting).
The current levels specified seem to indicate that the box is pretty much filled with the body of at least two MOVs.
It wants a 20A, duplex 240 VAC breaker. So, it does appear to be protecting both phases in ye standard home split phase setup.
Interesting for another reason: As I mentioned before, MOVs in general have a limited lifetime, especially if they get hit near their energy levels. When they fail, they can fail open or short. If one fails short, the breaker pops. In which case one's going to have to run down there and notice that the breaker's open.
If one of the MOVs in there fails open, there's still power, so one will get an audible alert.
In the fail-short case, then, it'll be a silent failure. Until one opens up the breaker box and looks.
I dunno. It's better than nothing, for sure. But, I've helped design and test surge-resistant equipment. The general idea is not to protect the entire neighborhood/central office/whatever. Putting chokes in series with the power feed, before the MOV/TVS stuff, does that isolation function, so one is only protecting oneself and not the universe. Which makes the variation in strength of the surge a more manageable problem.
And.. As somebody mentioned before this, surge protection isn't just for the occasional lightning strike. There's power crosses, pieces of industrial equipment giving up the ghost, Dr. Frankenstein pushing the knife-blade switches open or closed, and so on. City power is.. dirty.
For most people standard UL/CSA/EC protection built into equipment is sufficient for the purpose. There are exceptions: The aforementioned Farmer on the Flats being the obvious case, or somebody who lives literally next door to an electrical company power switching yard.
But there's always the possibility that one's house or the power pole right in front will take a direct strike from the 1 in 100 year bolt, I guess. But if one is worrying about things on that level, then I'd guess I'd say that the Siemens widget wouldn't be quite good enough: I'd go full farmer, and put the spark gaps and chokes in. Just like the old-timey telephone central offices do.
bo3bdar
Member
Great background and discussion, thanks for the details. I recently had a power outage event, not a lightning strike, and it broke my refrigerator. Fridge was not on a surge protecter, and I think it was killed by a startup surge after they fixed the lines, or possibly during the event which had an on-off-on-off cycle for an automatic repowering circuit that could not be repowered properly. (blown transformer upstream from me.)
As part of understanding whether I ought to have a surge protector on the fridge, I did some research. $1500 for a new fridge stings, and the answer is I definitely want a surge protector. No it's not a panacea, but it would have prevented this loss.
One thing I discovered that was news to me, as an EE, and I emphasize above- surge protectors have a limited lifetime. The MetalOxideVaristor (MOV) components wear out. The joule ratings are how much energy they can dissipate before failing, so one big event can do it, but also thousands of small events.
That means that if you have some ancient surge protector strips, they probably don't do anything anymore. Depending of course on how bad your power is. If you have some that are 10 years or older, you should think about replacing them.
Secondly- most surge protectors don't give you any indication if they are dead or not, if the MOV is worn out. This is a truly horrible design practice to have protective equipment silently fail but keep allowing current through. The better quality stuff has either an LED indicator for 'worn out', and the even better ones will fail open circuit so you know without having to look. Having to look behind my fridge on occasion is probably not going to happen, for example, but if the light is out when I open the door, I can get right on it.
WireCutter had a recent review of surge protectors that are worth your money. But quick pass- anything from TrippLite will be good. Long term, I expect TrippLite to be ruined by money grubbing short termitis, but they only sold out recently, so their current stuff is still solid. Get the ugly metal box versions, those are the real deal.
No way of knowing if it would prevent the loss even if it was a spike. It also could have been an extended low voltage situation.
Going along with this thread... Say a surge hits.
On the one hand, a big enough surge (10 kV!) or something will fry the house wiring and all that jazz, so one ends up with a house fire, and everything electronic is smoking away. That.. doesn't usually happen. Although if one reads some of the literature about EMP from nukes, an unplugged incandescent lamp in the house can pick up enough energy on the cord to blow the light bulb.
More likely is that there's an extreme overvoltage on stuff that Can't Take It. Interestingly, magnetics (coils, motor windings, stuff like that) have a natural immunity to that kind of thing. For those of you who don't know, inductors naturally resist a change in current going through an inductor. Capacitors are kind of the opposite: They resist a change in the voltage across the terminals.
So, say one has a 10 kV spike come down the wires from Ye Local Lightning Strike. Impress this across an inductor: One is not going to overcurrent and melt the inductor wires because inductors won't conduct on that kind of spike. What might happen is that a big enough voltage across a coil might be big enough to bust the insulation. But that's a hard call: adjacent wires in a coil are electrically close to each other, so there's this kind of big voltage divider across the coil. There might be a return wire laid close to the input wire, I suppose, that might have insulation break down. But all that is along the lines of handwaving: Maybe it'll happen, maybe it won't.
But something that's not handwaving has to do with the motor start capacitors. Three phase motors don't typically have issues with starting: The three phases naturally make a rotating magnetic field that drags the rotor around in the correct direction. A single phase motor doesn't have that luxury. So, an extra winding is put into the motor, hooked up to a capacitor, and said capacitor makes a phase shift that results in a bitty magnetic field rotating around ahead of the main one from the coil, and that's enough to get the motor turning. Once turning, it runs.
If one looks at an outside air conditioning unit's small pile of electronics, one will typically discover a couple-three capacitors that are designed (a) to get the blower fan moving and (b) to get the compressor motor running. Same is true on any motor in Ye Typical House, since, far as I know, all these motors are single phase, whether they're hooked up between 120 VAC and neutral or from 120/0degrees to 120/180 to get 240 VAC, single phase.
But there's this thing about capacitors: they have a maximum voltage rating. Exceed that and ye dielectric goes Pop!, and that's that for the capacitor.
From memory, most of the capacitors I've seen that get hooked up across house wiring are typically rated for 400V or 600V.
On the plus side for the motor start capacitors of the world, they have significant capacitance, 1 uF or so. At 1 MHz, that's an impedance of less than an ohm; so the self-protection function of a cap like that is to shunt the lightning bolt energy to ground. Which works, so long as there's... not.. a lot of energy. Which lightning bolts tend to have. (I, personally, have seem some rather blown-up boards subjected to this kind of thing and, no, a 1 uF cap won't cure this kind of problem.)
The other place in a fridge that wouldn't nicely survive a big strike would be the control circuitry. These days, that's mainly describing a computer. The transistors that make up a computer are rated, best case, for around 10V; worst case, around 1.5V. And to get to all that low voltage one has to get through the power converter, which consists of inductors, capacitors, diodes, switching power circuits, and, more likely than not, some MOV-based lightning protection circuitry. Those UL standards aren't there for play, you know.
So, flipping coins: Best bet what killed your fridge was the motor start caps. Next best bet is a fried power converter. The first one is a (relatively) simple fix, unless the motor start capacitor for the compressor is sealed inside the compressor housing (which happens); the second one, well, may as well get a new fridge.
I would think by your own insurance. Of course you could sue and possibly get something.
Ground lightning strike while Tesla Model S was Supercharging
Update to Model S disabled after close by lightning strike while Supercharging
TMC thread
Bottom line, Tesla engineers had the OPs Tesla Model S for a month and a half, after the lightning incident, while Tesla performed diagnostics and made repairs to an unspecified number of Tesla Model S components. Tesla returned the repaired Model S to the OP once repairs and testing by the Service Center was completed.
Update to Model S disabled after close by lightning strike while Supercharging
TMC thread
Bottom line, Tesla engineers had the OPs Tesla Model S for a month and a half, after the lightning incident, while Tesla performed diagnostics and made repairs to an unspecified number of Tesla Model S components. Tesla returned the repaired Model S to the OP once repairs and testing by the Service Center was completed.
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I live on a hill and a tree in front of my house was hit by lightning years ago. The lightning blew out a trench from the tree to my underground power line to my well pump. Burned up that pump along with a TV in my house and some other electrical equipment. I think it would be wise to unplug my Y during thunderstorms.
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