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Our power went down yesterday afternoon (December 12). The utility posted a message on their 1-800 number with expected repair time (a few hours later), but no explanation except that ~2000 customers were affected in our suburban area (Northeast USA).
Here's the weird bit -- LED bulbs stayed on, at reduced brightness. I got out a meter and measured 16 VAC in the house. This was enough to make useful light from "dimmable" LED bulbs (happened to be GE brand). After it got dark, we could also see that incandescent bulbs were giving off a faint reddish glow.
16VAC was also enough to keep a Netgear home router/Wi-Fi box going, it must have a switcher in the wall wart that accepts a really wide input voltage range?
Called a friend on the other side of the country who is an EE (with hardware background). He didn't have a good explanation, but suggested that in the process of bringing the grid back up there might be some big voltage swings--recommended unplugging everything we could. Went out to dinner and all was restored when we got home (no damage).
He also told a story from a rural area (near CA-Nevada border) where there was a power failure that upset the normally-balanced split phase -- instead of ~120V on both sides of neutral, the power went to 80V on one side and 160V on the other side of neutral. Equipment on the high voltage side failed due to extended over-voltage, seems that surge suppressors won't deal with this much energy.
Anyone? How does the grid fail-soft?
(Score: 5, Informative) by Ethanol-fueled on Tuesday December 15 2015, @04:36AM
Your friend was correct about the voltage swings, although this is done by the power company our of necessity. The reason why your friend mentioned unbalanced power levels on either side of the AC line is because, in the event of a massive power-failure, specially-trained linemen have to sever the power lines and weld monstrous resistors the diameter of large sewer pipes in series between the hot sides of the load. They may also weld a lower-valued but still large resistor similarly on the neutral side of the AC load, depending on the topology. This of course throws off the RLC time constant, meaning, it will take longer to get your power restored, but it is done to safely prevent damage to the infrastructure.
As for your router, and the LEDs, they can still operate because there is the ability to draw higher current in exchange for lower voltage - enough to operate due to the smaller levels needed to draw - they will just do so less efficiently. The bulbs operate differently because they are simply drawing current as a proportion to proper conditions, and as such are dim.
(Score: -1, Offtopic) by Anonymous Coward on Tuesday December 15 2015, @06:53AM
Its a masjesus miracle!
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @09:31AM
8-) You must be the life of the party at company events.
-- gewg_
(Score: 5, Informative) by LoRdTAW on Tuesday December 15 2015, @02:43PM
A more likely scenario would be an open neutral leg or failed voltage regulating transformer. Any properly built home in the last 60+ years would have its panelbox neutral and ground line connected together. The utility transformer would also be tied right to ground creating a return path but of higher impedance depending on moisture content of the earth resulting in a voltage drop. If the neutral opened before the earth return, all sorts of bad things could happen if there are no other transformers downstream as appliances would be in series with others and dividing the voltage. That could fry certain appliances. If there were downstream transformers, they could form an autotransformer setup and recreate the missing neutral.
One type of regulating transformer that would cause low voltage during a failure are known as ferroresonant transformers a.k.a. constant voltage transformer or CVT. They use an LC tank circuit on the same core to regulate the output voltage. They absorb spikes, boost low voltages and sags due to varying load conditions all without a single moving part. The only external parts are the caps. The tank circuit regulates the flux of the core. Voltage drops? More flux is allowed to build. Higher voltage? Less flux is allowed to build. If the capacitors blow, they safely go into a low voltage output condition as they can't regulate. Beautifully simple. They are very useful as they can compensate or long runs in rural areas where voltages can swing widely due to line impedance and varying load. So if the factory down the road turn a few big motors on and the line voltage begins to drop, the transformers take up the slack and boost the voltage.
I actually replaced a small one just last week in an electron beam welder which stabilized the voltage supplying the filament, focus and deflection coils. The foreman was confused as to why there was only 8 volts at the fuse from the output of the transformer. Turns out one of the old caps blew, the case was swollen a bit and was internally shorted. Repair was as simple as ordering new caps of equal voltage and value rated for inverter and line filtering duty. Loaded tested it and put it back on the shelf. Caps cost a grand total of 25 bucks. FYI, the input voltage is rated from 190 to 260V and the output is a constant 118V. We feed it from a 3 phase 120/208 Y using only two legs for single phase 208.
Another method of line regulation is the use of multi tap autotransformers where they switch taps when needed to boost voltage. It's possible that the autotransformer opened up or one of the transformers failed in a way to become an inductor and simply insert resistance to drop the voltage.
Either way, the fault was certainly one in a transformer or open neutral.
(Score: 0) by Anonymous Coward on Wednesday December 16 2015, @01:58AM
IMHO ferroresonant transformers are underrated, meaning, they should be used more. They work by core saturation, BTW, so if input voltage increases, you just get more input current flow, but not more output voltage because the core is saturating (clipping). They're not as efficient as a good switching supply, but they sure live longer.
(Score: 0) by Anonymous Coward on Wednesday December 16 2015, @03:42AM
They're more expensive than regular old silicon steel transformers, bulkier per watt, and run hotter (less efficient).
The only place I've seen them deployed where they were justified was in a product acceptance test setup where *repeatability* of results was paramount.
...then again, I live in a First World country with a pretty reliable electricity supply.
-- gewg_
(Score: 1) by driverless on Wednesday December 16 2015, @05:13AM
Ferrorresonant transformers are awesome, best power protection you can get (within sane price limits), they're almost indestructible. The downside to them is that they buzz like a small substation, and they're quite lossy, efficiency can go as low as 60-70% under low load, and you're throwing away this power all the time, i.e. even with no load connected or the load powered off.
Oh, another issue is size and weight, a 1500kVA Sola weighs in at something like 40kg (which contributes to its resilience, your power spikes are being absorbed by 35+kg of iron and copper, not some woosy MOV, which shouldn't even be used in any application involving power protection).
(Score: 2, Funny) by Anonymous Coward on Tuesday December 15 2015, @04:38AM
They are using power outages to give the NSA a narrow window to breach home networks to compromise computer systems.
Consumer grade routers fail to 'dumb switch' mode at poweron without router processor intervention. Given that consumer routers can take upwards of 15-30 seconds to initialize and flip the switch chips back into secure mode, it would give government agents plenty of time to access consumer networks, snoop mac addresses, gain access to management engines, etc before the wall goes back up, at which point compromised systems can phone home for further instructions.
This is hopefully just a paranoid rant, but food for thought among the more security conscious soylentils: Is your router the weak link in your chain of anonymity?
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @04:41AM
Brownout conditions can cause routers to fail into dumb switch mode until the next blackout or physical reset (unplugging and replugging power).
(Score: 2, Funny) by Some call me Tim on Tuesday December 15 2015, @05:00AM
My DSL modem and router are on UPS power and behind seven proxies, so I'm not too worried about this.
Questioning science is how you do science!
(Score: 2, Funny) by Anonymous Coward on Tuesday December 15 2015, @08:23AM
Yeah, I also thought of getting power from UPS, but the guys at United Parcel Service told me they deliver only parcels, not power.
(Score: 3, Insightful) by mth on Tuesday December 15 2015, @05:05AM
Most people use a router they get from their ISP. It would be much easier for the NSA to work via the ISP to put a backdoor into the router firmware: only a handful of people would have to be in the know for this to work and stay secret. A power outage is going to be noticed by pretty much everyone working at the power company.
Also, the security offered by a router firewall is often overestimated: typical setups don't restrict or monitor traffic coming from the inside, so if there is any program or device on the inside that is compromised, an attacker can use that to tunnel through.
(Score: 4, Informative) by frojack on Tuesday December 15 2015, @05:24AM
Consumer grade routers fail to 'dumb switch' mode at poweron without router processor intervention.
Your tinfoil is too tight dude.
Consumer grade switches are simple linux or BSD devices, and they route NO INBOUND connections until iptables is loaded.
Just like every other linux box. They don't default to dumb switch mode. In fact, most won't even pass outbound traffic until iptables is loaded.
Pretty sure I saw an NSA guy climbing your up your down spout up to your gutters. You might want to go stand watch on your roof for a few hours.
No, you are mistaken. I've always had this sig.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @08:45AM
He does have a point in, in some cases.
A firewall usually require two network interfaces. However, you can instead use a managed switch with two VLANs and only one network interface. If you're building your own, a managed switch is a more expensive solution, but when building millions of devices, we're likely talking chips at a few cents a piece. And here's the thing: Most home routers already have a four port switch built in. Except that's at least a five port switch (one port is hard wired to the router), and might as well be a six port one, with the last port used as the uplink port on a separate VLAN, thus saving a network interface.
In this case, switch may very well start out with no VLAN configuration, and only have that loaded when the router starts up (saving a separate memory chip to store switch configuration).
(Score: 2) by frojack on Tuesday December 15 2015, @06:23PM
Except not a single one that I have found works that way.
The WAN port is not physically on the switch group. Separately wired. So just because you can imagine a situation where this might happen doesn't mean this is common or that there is even ONE consumer router that operates that way.
No, you are mistaken. I've always had this sig.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @05:54PM
Unfortunately while the tinfoil might be on tightly, I can confirm that at least some consumer routers can fail into an unmanaged switch. It isn't the most common scenario, but it does happen. Now whether undervolting is a good way of triggering this, I can't tell you.
As for why, it is because you aren't dealing with a Linux or BSD box with these interfaces directly, you have an intervening switch ASIC either built into the router SoC or standalone. In braindead operation, you therefore just get a switch.
(Score: 2) by FatPhil on Tuesday December 15 2015, @08:34AM
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by Dunbal on Tuesday December 15 2015, @11:51AM
So in order to stop the NSA all you need is to stick your router on an uninterruptible power supply? :)
(Score: 1) by driverless on Wednesday December 16 2015, @05:18AM
You can get 12V UPSes, it's basically just a 12V SLA with a trickle charger and a failover switch. Unfortunately they're a bit hard to find (although you can homebrew one with a PicoUPS), the least difficult to source are the CyberPower ones, e.g. the DTC36U12V. So you replace your router PSU with one of these and get outage-proof (or at least resilient) power from it.
(Score: 5, Informative) by Hartree on Tuesday December 15 2015, @04:41AM
One possible thing that comes to mind is that someone on the line near you was running a generator just plugged into their house wiring without a disconnect and left the main breaker on. What with only energizing one side of the 220 line back to the pole you might get some weird low voltages out down the line after going through a couple of transformers.
This is dangerous for any linemen working on that line as it can put an unexpected voltage on a line they expect to be shut down.
(Score: 2) by frojack on Tuesday December 15 2015, @05:10AM
This!
You would be surprised how often this happens. Or current leaks through some rats nest behind someone's desk with half on one circuit and half on another, and no fool proof way to depower the entire circuit, while power leaks through what should be low-voltage wiring.
Its Christmas lights season. Who knows how many snowbanks and puddles someone ran extension cords through. It could be leaking from between neighbors or _cough_ borrowed power.
16 volts is an odd number. That's far more unbalanced than is likely to happen in the real world.
And your friend was right, shutting everything off was the way to go. But pulling your main breaker would have been the smart thing to do, as no mater what you shut off, you are bound to forget something somewhere and it could cost you a major appliance.
No, you are mistaken. I've always had this sig.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @05:12AM
Yep, jerks with generators and suicide cords suck.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @05:20AM
In my experience, they blow... along with their breaker, if they are lucky, and more expensive things, if they are not.
(Score: 1) by Some call me Tim on Tuesday December 15 2015, @05:14AM
I would bet you're right. Probably some dummy that doesn't have an automatic disconnect installed. I'm the last house on the neighborhood feed and I can tell when someone turns on a high load appliance, lights flicker, UPS units alarm, kind of a pain in the middle of the night. I'm looking at a whole house UPS, they've really come down in price.
Questioning science is how you do science!
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @05:42AM
Thanks tesla!
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @05:22AM
Could this also occur with a photovoltaic array or wind generator on a neighbour's property? I guess this would require a faulty intertie.
(Score: 2) by carguy on Tuesday December 15 2015, @05:44AM
I'm the OP. I like the explanation of a neighbor with incorrect generator setup, except for one thing. The 16 VAC appeared almost immediately after the failure. As I remember it, the lights went out (including the LED bulb) and back on a couple of times quickly. This (I believe) is the utility's circuit breakers resetting a couple of times to see if the fault has gone away. After that the power was off for a few seconds and then the LED came on at the dim level.
So the 16 VAC was on the line almost immediately after the final cutoff. It was also on at our next door neighbors -- an elderly couple who were very pleased that I brought over a couple of spare LED bulbs. Saved them trying to get around by flashlight. They also had 16 VAC for a few hours, confirmed by volt meter. Don't know if they are on the same transformer as us or not--will have to check sometime.
How about this -- the utility circuit breaker actually was able to reconnect, but during the few seconds of the failure/overload a transformer winding partially shorted and the output voltage was greatly reduced. Could this do it?
There was another short power failure today, but this time I watched the LED bulb and it did not stay lit. So no repeat (yet).
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @06:30AM
What you have then is an old-fashioned soldering gun.
Not a lot of voltage across that 1 turn but, with essentially zero ohms limiting the current, it's gonna pull a whole bunch of current.
The transformer will self-destruct before long--if it doesn't blow a fuse first.
-- gewg_
(Score: 2) by LoRdTAW on Tuesday December 15 2015, @02:44PM
See my comment above: https://soylentnews.org/comments.pl?sid=11142&cid=276656#commentwrap [soylentnews.org]
(Score: 1) by driverless on Wednesday December 16 2015, @05:22AM
A common problem with PV, which is why they're supposed to have anti-islanding capabilities built in. This means they stop producing power in the event of a grid failure, so they don't electrocute the people trying to repair the fault, or at least stop feeding it back onto the grid.
(Score: 2) by LoRdTAW on Tuesday December 15 2015, @02:25PM
I'm surprised the circuit breakers don't blow. My only guess is there is enough impedance to prevent this but I still doubt that a ~6kW gas genset could ever back feed the grid without tripping one of its two 20 amp breakers. Though, I have heard of this happening. My guess was in those situations is the utility lines become isolated enough to prevent generator loading and just float. So if someone has their own little transformer and their high voltage feeder fuse blows, they can still backfeed the transformer and cause a floating high voltage potential on the primary.
(Score: 3, Interesting) by VLM on Tuesday December 15 2015, @04:22PM
If you try to power an entire neighborhood off a small generator, combined with trying to make the governor smoother by having a heavy flywheel, I've heard stories about the crankshaft of the generator shearing when the output is shorted either by a wiring error or back feeding foolishness. Usually cars can't be damaged by stalling them, but often enough you can damage a generator trying the same trick. 60 Hz is pretty slow and you can have quite a torque spike in the shaft before mechanical breakers open. Most backfeeding incidents end in a loud bang, sudden silence, then swearing about all the damage to the engine.
In practice there's two problems.
Linemen aren't complete idiots and know how to handle electricity, but after working 36 straight hours without a break after a hurricane because he likes overtime $$$ and he literally falls asleep on his feet and falls out of the bucket asleep to his death, then everything gets kinda smoothed over such that no one is to blame because he must have gotten shocked by a back feeding generator or WTF, causing a minor shock that scared the hell out of him so he lost his balance. Or just plain old lost his balance, how does an old timer lose his balance and fall to his death, must have been a GD backfeeder. A close second is after 36 straight hours of work literally spacing out and forgetting which side of the circuit is currently live. If I climbed a pole I'd have an interesting time not getting killed, but these guys know what they're doing and its not an issue.
The other problem is see first paragraph generators hooked up incorrectly generally don't operate for long, and as such are not a significant threat however people stupid enough to do something that stupid, will none the less perform all manner of other idiocy likely leading to death, fire, etc. Like run circuits between hot and ground, making massive ground loops by making multiple gnd-neutral connections, staple stranded extension cords to rafters instead of installing romex, make virtual 220 circuits by grabbing two opposing phase 110 circuit hot leads, wire their kitchen stove for 4-wire then hotwire a 3-wire cord/circuit onto it, all kinds of stupid stuff. Even non-electrical stupid stuff like run the generator in their basement or garage to prevent theft, run it in the rain unprotected, refill the gas tank while the generator is running, look for gas line leaks with a lit match, etc. Its a general denigration of "hold my beer and watch this" culture rather than specifically making fun of one practice of that culture.
(Score: 2) by LoRdTAW on Tuesday December 15 2015, @05:36PM
I've seen some pretty dumb stuff myself. The best is I worked with a guy who refilled a small coleman gas generator while running on a carnival job that was running a bouncy castle and cotton candy machine. The gas splashed and hit the hot cylinder head and I assume the exhaust pipe. The whole thing flashed, so his reaction was to whip the gas can around and throw it. Well that resulted in him splashing gas on his arm which caught fire and then heaved the gas can at a wood fence which went up in flames. My uncle was there with his ride truck and said he heard screams and saw a plume of black smoke coming from behind the bouncy castle along with people running away. Fire department came and put the fence out and the gas that was on the ground burnt itself out. Dumb dumb who filled the tank was treated for minor burns as he was at least smart enough to stop drop and roll to put his arm out before it was severely burned. We had to pay for the fence and the generator needed a new fuel tank. We then made him pay us back for the fence which wasn't much. That dude always caused all sorts of cartoonish calamities. Once he actually did the paint can on a board across two horses that gets turned into catapult after something heavy fell on it and splashed white paint all over the yard, equipment, two vans and himself.
(Score: 4, Informative) by Some call me Tim on Tuesday December 15 2015, @04:47AM
Consumer grade surge suppressors aren't designed to handle extended over voltage loads. They shunt to ground momentary spikes from 330Vac (UL listed devices) and up for very brief amounts of time. The components (MOV's) will also degrade after a number of spikes and then you lose all protection. https://en.wikipedia.org/wiki/Varistor [wikipedia.org]
Questioning science is how you do science!
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @05:00AM
> The components (MOV's) will also degrade after a number of spikes and then you lose all protection.
The good surge suppressors will "fail dead" - once the MOVs are burnt out the power-strip will stop working. Some go permanently dead, others act sort of like a circuit breaker and you can turn them back on and use them as a plain old power strip. The shitty ones just keep working even though all the suppression has been burnt out.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @06:58AM
once the MOVs are burnt out[,] the power-strip will stop working
A metal-oxide varistor used as a surge suppressor is a -shunt- device.
It would be interesting to know how the failure of that (typically getting higher in resistance and breakover voltage with age) disables the strip.
I suppose that they could specify the device so that it is *always* pulling some current and, when that current falls below a threshold, additional circuitry could cause a relay to drop out.
That kind of spec would be really non-standard and the protection device would consequently have a shorter lifespan.
-- gewg_
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @12:42PM
You can have a computer chip count the number of power spikes, then assume the Varistor is damaged after some limit (they are rated by the number of joules after all).
I have a fairly expensive one that promises to beep annoyingly when the protection runs out. Not sure if I think that is a good thing or not... It also has a low-pass filter that will filter the smaller spikes.
(Score: 2) by el_oscuro on Wednesday December 16 2015, @12:08AM
That's true. A number of years ago, I was TDY to London and had to setup US spec computer equipment. So we had transformers to convert the 220 to 120. Part of our setup process involved testing of all of the components prior to use. It was an important event and our shit had to work.
So I plugged in the transformer, plugged the laptop in, and booted into the DOS application we ran. Our laptops were the heavy duty Grid Compasses with titanium cases. Anyway, it ran fine, so I shut it down and plugged in the surge protector...
... Which promptly exploded. We ran a voltage check on the transformers output and instead of the expected 120V it was putting out almost 400V. I guess I should have tried the surge protector before the laptop, but I had never seen one explode before.
I guess they don't make computer equipment like they used to.
SoylentNews is Bacon! [nueskes.com]
(Score: 3, Informative) by Anne Nonymous on Tuesday December 15 2015, @05:36AM
It's Bigfoot in his flying saucer disrupting the grid as he brings JFK back for Elvis's birthday party.
(Score: 4, Informative) by Anonymous Coward on Tuesday December 15 2015, @06:25AM
___ ________
)( |
)( 120V R 60V
)(_____ _| <--- broken or badly corroded neutral
)( |
)( 120V 3R 180V
___)(_______|
The power company delivers the juice to your neighborhood as single-phase high voltage.
It isn't split-phase until it exits your local step-down transformer.
The usual reason for the voltage in 1 part of your house being hugely different from another part is that the neutral connection at the panel is crappy or missing.
The voltage that appears on each "phase" is then determined by the voltage divider made up of the stuff connected to each "half" of the load.
If one "half" has a whole bunch more stuff connected, that "half" will read a lower voltage.
As others have said, this doesn't appear to be the fault of the power company.
There is likely something odd going on with a neighbor's non-kosher setup.
-- gewg_
(Score: 3, Informative) by Whoever on Tuesday December 15 2015, @07:31AM
It could also be (as happened to my neighbour) a broken neutral cable from the local step-down transformer to the house. In this case, it would be the power company's fault.
(Score: 5, Informative) by LoRdTAW on Tuesday December 15 2015, @01:27PM
It's not always split phase. Some areas will feed you from a 120/208 3 phase Y using two of the three phases. Makes balancing a 3 phase high voltage feeder much easier. If the phases are labeled A, B and C, homes are connected A-B, B-C, C-A to achieve balance. The only downside is appliances expecting 240V will operate at slightly reduced power. But it usually isn't a problem.
And don't expect everything to be uniform, power companies do weird stuff. I live in south Queens a my home is powered by 120/240 true split phase. If you look at the poles, there are three wires that feed every house on the block. But when you get to either corner, you can see that the three wires met up with four wires from a 3 phase setup. This is not kosher and the lines could never be connected. So the hot legs are actually isolated with insulators on each side of the block and only the neutrals are connected. So my block is the only block in the area with true 120/240 split phase fed from a single 100KVA pole transformer. Everyone else has 120/208 off of a 3 phase Y. Why? Who knows. Maybe it was originally supposed to be multiple 120/240 feeders and they canned the idea or upgraded and our block was forgotten.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @01:37PM
no explanation except that ~2000 customers were affected
this doesn't appear to be the fault of the power company
Uh how do you get that it is not their fault? They may have done nothing 'wrong' per se but they are quite responsible for it.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @09:01PM
Yes, -the outage- was certainly due to the power company's stuff.
As soon as the utility came back up, all the voltages were back to normal, so a flakey neutral isn't indicated--not theirs or OP's.
The mention of 3-phase by LoRdTAW injects the possibility of a lost phase--but I have never been in a place where that is a thing in purely-residential areas[1].
I also don't recall seeing a 3-phase feed under 177V, so I dismissed that possibility.
[1] Requiring an additional sizable transformer yard and additional large wires with no monetary gain from that stuff.
Working from that dataset, my conclusion is that while the power company's feed was dead, logically, the phantom voltage was due to some cause other than the utility.
-- gewg_
(Score: 2) by sjames on Tuesday December 15 2015, @06:15PM
It can be a lot of things depending on the exact setup of the neighborhood wiring. If the power company loses the neutral, suddenly fairly simple circuits effectively become comp[lex and somewhat unpredictable. Much moreso if it's a neighborhood that has a 120/208 wye setup. For example, two lights on seperate phases are suddenly effectively connected in series across the phases instead. Turn one off, both go off. But just to confuse matters, the (disconnected) neutral is bonded to ground, so if one light is off, the other is now powered by 208v but with a high value parallel resistor and capacitor connected in series. Who knows what voltage drop it might see? (it depends on the weather, soil composition, solar activity, etc). Your TV might end up in series with the neighbor's dryer.
(Score: 4, Interesting) by ledow on Tuesday December 15 2015, @10:32AM
I bought my girlfriend an electric kiln. This is a 32A monster thing that weighs a ton that you plug into a commando connector (the building site connectors - 220V 32A in my case, which needs a slightly-larger-than-normal version). I bought it second-hand because new they cost more than anything I've ever bought in my life.
We paid an electrician to put an RCD and external commando connector on the side of the house in the alleyway (the idea being that we could use it for other things, maybe even an electric car someday). He cabled it all in, said it worked, certified it, and left.
When I plugged in the kiln, I hadn't had a chance to test it previously. 32A raw connections are rare at 220V in domestic scenarios! We plugged it in, it lit up, but that's all it did. Not action at all, no heat.
I ordered the circuit diagrams from the manufacturer, I dug out all my electrical knowledge, took the thing apart and COULD NOT for the life of me see a problem.
So I bought some adaptors and plugged other things into the 32A commando connector. Nothing. The extension lead lights would light up but they wouldn't power. When I voltage-tested, I got about 20v. Extremely weird.
I had wanted to avoid exposing myself to the kinds of power in that box and playing with fuseboxes, but eventually I just switched the house electric off, tested I was safe, and opened up the box on the side of the house.
I found that he had wired the neutral and live into the huge power switch.
He'd wired the commando connector to Live and Neutral terminals provided below the switch.
But he'd only wired the live in between the two. The neutral was completely disconnected and two separate wires coming in and out.
So much for electrical certification!
When I wired the neutral in properly, it all just worked, kiln included, and has worked for over a year now.
Check your neutrals. I bet you have a similar situation.
(Score: 2) by FatPhil on Tuesday December 15 2015, @12:32PM
Absolutely. However, out of paranoia, check everything. The first thing I did when I started house-hunting was to buy a simple mains socket tester. Plug it in, and a pattern of leds lights up telling you what's good and what's wrong. This was after nearly electrocuting myself on some small consumer electronics device on the first day in my previous place - there was god-knows-what coming out of the *earth* connector. Paid a professional to fix that, I'm a wuss.
> 32A raw connections are rare at 220V in domestic scenarios!
Yeah. It's strange that you're not using 3-phase (or 2/3 of 3-phase)? My sauna stove is available in 1-phase 230V configuration at 40A, but I have a 3-phase configuration at 400V and much lower current per phase. Everyone I know (who has a sauna) has the 3-phase install, but that's because in this part of the world saunas are designed in at building/renovation time, not afterthoughts.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @01:02PM
Those little detectors do not detect hot ground and neutral (sometime happens to defeat the test, I have read). You can use a voltage sensing pen for that.
(Score: 2) by Runaway1956 on Tuesday December 15 2015, @04:33PM
Depending on what part of the country you are in, the electric company may make 3-phase "unavailable" in residential areas. Where I live, there is no 3-phase to the homes. Of course, there is 3-phase at the highway, and if I were to beg and plead, they would come out, run the third wire down the county road, and hook it up to my meter loop. The fee would be as much as several month's electric bills. If I lived in town, or if I lived at the other end of the property, the 3-phase would be a hell of a lot closer, and cheaper, but still not cheap. Different states have different laws, of course. When I was a kid, my dad wanted 3-phase 480 volt, he just picked up the phone, and it was hooked up within a couple days, no problem, no big bill.
Abortion is the number one killed of children in the United States.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @01:47PM
I don't know about where you live (you didn't say) but in the USA the Neutral and Ground wires are to be connected at all times and never go through a switch. Those wires should go uninterrupted all the way back to the bus bars in the main circuit panel, the only exception being with a GFCI or AFCI breaker where the Neutral passes through the breaker as the device needs to monitor the load on that wire at the same time as the Hot.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @03:23PM
Devices connected to the load side of a GFCI receptacle would be another situation where the neutral is not directly connected to ground at the panel.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @10:34AM
Welcome to Nightvale.
(Score: 2) by sjwt on Tuesday December 15 2015, @10:51AM
https://en.wikipedia.org/wiki/Brownout_(electricity) [wikipedia.org]
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @02:44PM
wikipedia is a bit low on "brownout".
i happen to have a bog normal 50Hz ~220V/380V three-phase four-wire connection to a Y-transformer.
Were i live we don't have many small powerplants but rather a big lignite burner that has to service a rather
big physical area (of course it is interconnected to other power plants in the country).
sometimes we get "brownouts"; that is one phase is at about 217 V while the other ones could be ~76 V and ~117 volts or so.
during one of these brownouts i had to do some errands and passed the "service bus" of the electrical power provider
and they were replacing (again) a fuse on the medium 22kV lines going to my area.
the 22kV fuse blew on one phase and so the transformer was only fed by two-phases from the 22kV side and then, because it was a transformer,
it transformed some of the working phases onto the "dead" phase but only yielding 76 V or 117 Volts or such.
so if a supplying phase on 22kV breaks a fuse then you get a brownout also.
btw, asking the repairmen about the amp rating for the (massive) 22kV they told me it was 12 Amps ^_^
i guess they cannot put a bigger fuse because else the 22kV lines would need to be replaced or else start sagging and/or over-heating.
(Score: 1) by crb3 on Tuesday December 15 2015, @11:49AM
> He also told a story from a rural area (near CA-Nevada border) where there was a power failure that upset the normally-balanced split phase -- instead of ~120V on both sides of neutral, the power went to 80V on one side and 160V on the other side of neutral. Equipment on the high voltage side failed due to extended over-voltage, seems that surge suppressors won't deal with this much energy.
> Anyone? How does the grid fail-soft?
My parents' house went through this when one of the live lines, plus a center-return somewhere, snapped in a windstorm. Return path for the hot line was then through the local stake to the stakes of nearby still-connected houses. A surge-suppressed strip on the high side didn't just burn out, it burned up and started a fire; they're just now finishing up getting things set up as they were before, with a lot of replacement electronics, after a room repair.
Lessons: don't put surge-suppressed strips in closets where they're not immediately visible when they decide they've had enough. And don't automatically assume that the internal breaker will pop when that happens. And consider Murphy-proofing by taking the house offline when microbursts are forecast: this was the second time their power went strange, but the first time it set fire to the place.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @01:18PM
In the late 70s, all the lights in our house would get very bright, then very dim, and continue that cycle for awhile. It was like the lights going crazy in the movie Poltergeist, which was very strange because our neighbor was one of the actors in that film. The utility came out and found the lead-ins from the pole transformer had too much resistance in them, replaced and back to normal. At our shop, we had a blackout that affected the entire community. Everything was dead except all the fluorescent tube lamps were still on. I checked the voltage and it was only about 6 volts. I guess once the bulbs are on, it doesn't require much to keep them going.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @03:36PM
And Bob's your uncle.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @03:46PM
No, bob's my dad and brother.
(Score: 1) by driverless on Wednesday December 16 2015, @06:02AM
Bob's my Uncle Dad. Cousin Mom is Lucy.
(Score: 2) by VLM on Tuesday December 15 2015, @04:02PM
16 VAC across maybe a 10 meg input impedance meter, sure. That's not much of a current.
Google up "induced voltage".
People think power outages are like magic spherical video game EMP bombs but reality is unless your whole metropolitan area lost power the HV lines are up. Even if your subdivision lost power the MV lines might be up. Quite likely there's power close enough to the disconnected lines to couple some in.
When you have a short the auto-reconnector thingies fire a couple times and for a second every five seconds in case it was just an intermittent, it'll reset the circuit breaker for a moment. Maybe a couple times. But if you're still drawing sparks a minute later off a downed line, either it failed open somehow and the breaker didn't trip, or if they're really small sparks its just induced current from lines near enough by that are still up.
For lack of a better place, there's high voltage towers going thru a nearby county owned hiking park and its tradition for kids to wave old fashioned fluorescent light tubes in the air under the power lines and they light right up.
You kids and your new fangled switching power supplies, the rectifiers probably have such a fast switching speed you may be seeing rectified local AM radio station pickup not induced 60 Hz current. After all a giant grid of copper wire, if not connected to power, is a hell of an AM radio antenna, and making a LED dimly glow is not that ambitiously beyond a crystal radio set's power. Of course the inductance of the transformers probably doesn't help. Then again maybe just the drop to your house, from your house to the pole to the transformer would make a decent random wire radio antenna when its not powered up. What your cheap multimeter designed for DC and 60 Hz things when fed a couple MHz AM radio signal is mysterious, could be 16 VAC on the display, who knows what an oscope would see.
So I'd give it about 50/50 odds that its simple induced power or AM radio antenna pickup making modern switching power supplies happy. You're not going to run a clothes dryer off that, but then again it doesn't take much to make a couple LEDs dimly glow.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @04:17PM
And then, of course, there is this lovely big cell we call Planet Earth. On a good low-impedance meter you can always read a potential between any two ground rods, which usually increases with distance, and is one reason why proper bonding practices specify single-point earthing for each service drop.
You should've seen the fun when an idiot "safety director" decided to have maintenance drill and pound ground rods for every machine in a factory instead of using the building column grid. When I saw what they did I just told the plant engineer to put it back like it was and sent them my bill, along with some germain NEC reference excerpts.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @04:22PM
Did you know... if you string a wire parallel with high tension powerlines you can get free electricity even though it's not physically connected? Don't let the utilities catch you though, they'll send you a nasty C&D and make you remove it.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @08:25PM
I used to be our companies "safety inspector"... that is until I caught upper management changing my reports. I told them to shove it and to find someone else to do it, which was pulling me away from my main duties anyway for a lousy extra 1 hour of pay. The dipshit that took over only pencil whipped the inspection reports, without actually checking anything. About a year later a fire broke out and the first extinguisher that was used didn't work. The inspection tag on it hadn't been filled out since the last time I checked it.
(Score: 0) by Anonymous Coward on Tuesday December 15 2015, @05:54PM
i try not to give google more use than necessary. Shame on you for making them install CDNs and force them on us for your convenience. Someone should "kleenex" up the mess caused by them and "xerox" the results for us all to see. Cause will let you google it for me, but I wont search it on them myself. I'm pretty left wing, so I am going to go duck it up instead.
(Score: 0) by Anonymous Coward on Wednesday December 16 2015, @12:14AM
The most famous example of induced current was The Carrington Event. [wikipedia.org]
Telegraph equipment was welding together or exploding.
When checking whether electrical feeds are alive, an electrician doesn't tend to use a high-impedance voltmeter.
He will use something that draws a bit of current. [google.com]
That gets rid of phantom voltage readings.
I have a 10k 5W resistor I got out of my junk box and mounted on a dual-banana feedthrough connector.
I hook that to my meter when checking household voltages.
It pulls ~2W @ 120V and ~6W @ 240V.
Similar kind of idea as a Wiggy.
-- gewg_