Along those lines, I would think that if "ethical" and "security" are a problem, having valuable data on a phone is downright stupid. How many people lose their phones? I happens all the time.
My Blackberry is protected by a passphrase and auto-locks after 30 seconds of inactivity. (which is set by BES policy, it's not something I can configure).
The data stored on the phone is encrypted.
If someone picks up my phone, they have 8 guesses at the passphrase before the phone wipes itself. As soon as I report the phone lost/stolen to my IT department, the phone will be wiped remotely (or will be wiped the next time the phone is on the cellular network).
I'd say that someone has a better chance of getting to my secret data by stepping into my office when I step out (5 minute auto-lock timeout on my desktop and no disk encryption) than getting to it from my phone.
As other posters have pointed out, there are valid reasons to be cautious about the cloud. He's not saying "ethical" as in immoral, but ethics as in a professional responsibility to protect client data.
Until a cloud service takes the blackberry approach where the only person that has the key to decrypt the data stored on their server is the customer himself, Cloud services will have a hard time assuring customers that their data is secure and won't be inadvertently released to another customer. (not to mention the case where a cloud employee accesses the data).
Even something seemingly innocuous such as mail envelope information may be protected under various data protection laws. A breach of data could be financially devastating to an organization that's covered under these laws. (PCI, HIPAA, DoD security levels,etc). Even data that is not protected by law may be so valuable to the organization that they don't want it inadvertently shared with others in the cloud.
Even if the cloud service provider guarantees that the customer's data won't run on the same hardware as other customers, there's still a chance for cross contamination, like if the service provider accidentally restores a backup tape on the wrong machine, or an employee copies a configuration file to the wrong server.
Is there a cloud email provider that allows for on-disk encryption? (I'm not talking about PGP encrypting all of my messages so even the recipient can't see them without decrypting, but I mean storing the data encrypted on disk and not decrypting until it's on my device).
I've known people that are that paranoid, and they work in healthcare and their job is to comply with HIPAA.
Isn't Wifi last decade too? And Bluetooth. You're so archaic, my next phone will connect to the net via TCP/IP: "Traditional Carrier Pigeon Internet Protocol". Latency sucks, but bandwidth is incredible. I've seen theoretical transfer rates in excess of 1Gbit/second (with latency in the 1 hour range, depending on your distance from home).
I don't treat my phone as a little computer with much the same capabilities as my big computer because it's lacking the screen and keyboard that my computer has. If I want a document on my phone, I just email it to myself. Am I supposed to explain to my mom how to STFP her recipes to phone?
For most small businesses their data is safer in the cloud than on their own servers (though the original article submitter is likely savvy enough to keep their servers patched and secure).
I tried to convince a small non-profit that they should move to Google Docs to get calendaring and access to files from home. They refused, saying "We don't trust them with our email and documents, what if hackers broke in". Yet they were using their ISP's POP3 mail server for email with no password encryption, and their office "fileserver" was the receptionist's computer and the whole reason I was visiting them was to help clear malware off that computer when their ISP threatened to cut off their internet service because that computer was part of a botnet and sending out spam.
If you have ethics and security issues with storing data in the cloud, then shouldn't you also be looking for a device or application that encrypts sensitive data?
Do any Android phones do encryption natively? I've heard that the upcoming Droid Pro claims to. I know the iPhone has encryption support, but I don't know how whether it encrypts all application data or only data that Apple deems 'sensitive'.
The point isn't that you personally can see the source code (unless you're a developer), but that others can see it and extend and enhance the product.
Most people don't value open-source in home appliances, but If you had an open source (and flashable) alarm clock, and if you hate that the snooze is always a constant 9 minutes, it's likely that someone else thought the same thing and released a patch to lat you set the snooze to whatever you want.
Likewise, if you have an android phone and hate that it doesn't support your VPN at work, you can bet that someone else had the same problem and ported a Cisco compatible VPN client to it.
The destruction would have been far less than that of Nagasaki or Hiroshima, since it would have detonated on the ground, instead of high in the air over the cities in Japan.
I wonder if that's what that other guy meant when he said this:
And that bomb detonated at an altitude of 500m to maximize destruction. An accidental surface detonation in an airplane crash is going to have a much smaller destructive zone, even though the bomb is twice as powerful. So even if that bomb had detonated in the crash, there would be survivors even on the airbase itself.
A an accidental detonation from a bomb twice the size dropped on Japan would not result in " immediate death toll" that " may have reached six figures".
In 1950, the population of Fairfield was around 3000. I don't know the size of the air force base, but I don't think it was close to the 6 figure range (today it has 15K military and civilian workers, it may have been higher during the cold war). Suisun City today has a fraction of the population of Fairfield.
Just 3km from the hypocenter of the bomb dropped on Nagasaki, most structures withstood the blast and most people that were indoors survived the initial blast.
And that bomb detonated at an altitude of 500m to maximize destruction. An accidental surface detonation in an airplane crash is going to have a much smaller destructive zone, even though the bomb is twice as powerful. So even if that bomb had detonated in the crash, there would be survivors even on the airbase itself.
Even in a 1 megaton blast (50 times as powerful as the bomb dropped on Nagasaki) , there's a 75% survival rate just 7.5 miles from the blast.
Thank you! You're absolutely right, I used 100 * 10^9 instead of 100 * 10^12 for the capacitance so I was off by a factor of 1000 -- thanks for the correction!
That makes perfect sense, but I wish Eivind Eklund would elaborate on his comment that some places use two hots but no neutral. What are they hot in relation to? Just to each other? So it'd be kind of like an outlet with an isolation transformer? Is there any ground reference at all?
Aw, man, you're going to start being civil. Okay, me too.
I thought I was already being civil?
More generally, let's go over this from first principles.
1. You can't get electrocuted or feel a shock unless there is current flowing. I can't prove this one but it's what Wikipedia says too.
Agreed.
2. You can't have a current flow unless there is a potential difference. That's derived from Kirchhoff's mesh rule: the sum of the emf in a circuit is the sum of the potential drop in the circuit.
Again, no arguments here.
3. You can't have a potential difference if there is only one wire, because there's nowhere to establish a difference: there isn't a circuit, by definition.
I disagree a little here. You don't need two "wires", just two "conductors". It seems like it's only a distinction in semantics, but the distinction will become clear later.
4. As such, if you touch a single wire, there cannot be a current flow. (I'm neglecting the capacitance of a body, but I specifically noted that in the original post -- and that's what I measured with the Keithley, and it's negligible.)
You still haven't convinced me that a rabbit has no path to ground. I have no reason to disagree that in your lab with an insulating floor and insulated shoes that your body would conduct practically zero current to ground, but in the real world, electrical shocks and even electrocution can result from contacting a hot wire, no need to contact both hot and neutral at the same time.
5. Cutting a single wire, regardless of its voltage, still does not provide a potential difference, as there is still no circuit.
I still don't see how cutting the wire matters -- the rabbit did not cut the wire (did it? Do they really chew through the wire? I assumed they just bite through the insulation). In any case, can we just throw #5 out since it has no relevance at all?
Let's review to my original post, just to make sure everything is covered.
I said: "if the appliance isn't drawing power right then" -- which means no current is flowing, which means the entire line is at the same potential. So, no potential difference, so no way for there to be any current flow.
Here's where you've lost me again -- regardless of whether the power is on, the hot wire will have a potential of 120V at all points along it, and the neutral will have a potential of 0V. (in reality, voltage drop of the wire will cause a tiny difference in potential along the wire (increasing as current draw increases), but not enough to be meaningful.
Likewise, I said "as long as they only chew through one wire at a time" meaning the rabbit does not establish a potential difference between two lines: the rabbit is at a high potential with respect to ground but there isn't a circuit, so no current can flow.
This is the source of our disagreement - I say that any animal on a normal household surface without special protective gear will have a path to ground. It may be conductive or it may be capacitive, but it's a path nonetheless.
Particularly if he's chewing a refrigerator power cord, since in most cases he's going to be touching the metal (grounded) frame of the refrigerator to gain access to the cord. After looking at my refrigerator, I don't see how a rabbit could reach the part of the cord near the floor without touching some part of the refrigerator.
Uhhh. Okay, explain this to me. Since I'm both an electrician and an electrical engineer you can use the fanciest words you want. I have a wire. It is connected to 110 volts. It is not connected to anything else, which is why I specified that it is *unloaded*. I cut it in half.
To be fair, you said you can lick the hot wire without danger of shock, not just cutting it. Obviously if you clip with wire with insulated wire cutters you'll be fine.
Your path to ground is through the ground. What kind of surface are you standing on? Is it clean or dirty? What kind of shoes are you wearing?
My shoes are surprisingly conductive -- if I put both feet on my stainless steel cabinet, I get around 30000 ohms of resistance from my fingertips to the cabinet according to my multimeter. So there's my path to the floor. The NEC says to treat the concrete surface that I'm on as "grounded", so there's my path to ground.
Are you sure you're an EE? You mentioned that only a few hundred thousand electrons might flow due to capacitance alone - do you know how vanishingly small that amount of current is? The human body will have around 100pF of capacitance to ground, how much current (and how many electrons) will flow to charge 100pF to +169V and then discharge and charge to -169V every cycle?
oh wait, it's been a while since I've done any real EE type math, but I seem to be getting an effective resistance of 26500 ohms for a 60 Hz signal through a 100pF capcitor, so enough current will flow through capacitance alone to give you a shock. Did I do my math wrong?
I have gotten shocked before from a lamp where the cord had frayed and let the hot wire touch the lamp body. I got shocked when I touched the lamp while standing on a dry wood floor wearing rubber running shoes. One does not need an obvious path to ground to get a shock from 120VAC.
Where are these places? I thought most modern wiring practices use a hot and neutral wire (where neutral is at ground potential). They don't always make a distinction between hot and neutral at the outlet since often the outlet is unpolarized, but there is still a neutral. I'll admit to being completely unfamiliar with most asian wiring standards.
Is there any bonding between the incoming power legs and ground? What is the potential between the two hots and ground?
That's not how electricity works. The hot wire is hot regardless, but if nothing is drawing power, you can cut the hot wire with impunity. You can grab it and lick it, and your body will run up to 110V but if there isn't a path to ground, there isn't any current flow. Here's a great video [youtube.com] about a guy who works on high voltage lines, who is crawling along an uninsulated million volt line, working on it, because there's no ground return path so he's fine.
Tell me again how we moved from a rabbit under a refrigerator to an electrical serviceman on a high tension wire who takes great pains to ensure he's not grounded when he touches it? I was not describing how electricity works in all possible conditions, but in the conditions given in the post. Are those similar conditions? Do you see *any* difference between the two situations?
Why don't you do an experiment -- walk up to your refrigerator outlet (which should have no GFCI to protect you), stick a screwdriver into the hot side and hold onto the metal shaft of the screwdriver and see what happens. It's likely that you'll feel a shock. If you're unlucky you could die.
Its only 'hot' to you if your body completes a circuit to ground. Its perfectly possible to cut a hot wire if there is no chance of the current going through you to ground. Its how high voltage linemen who repair high tension lines via helicopter do it. The problem occurs if they get too close to a mast ( which would form a ground circuit ), or the other 'cold' conductor.
Yes, you are right. I would like to amend my post to say:
If the rabbit is wearing proper protective gear, including insulating rubber shields over his teeth, a dental dam in his mouth to prevent saliva from wetting his teeth and tongue, rubber booties on his feet to insulate him from the ground, and a full-body rubber jacket to prevent any part of his body from contacting the floor, in those circumstances, the rabbit may be safe from electrocution if he chews through the hot wire. In normal conditions found in most homes, with the normal clothing typically worn by rabbits, he'll likely provide a good enough path to ground to feel a shock when he chews through the hot wire.
Oh, and if the rabbit happens to be in a helicopter that is properly bonded to the power line...in those conditions he may also chew through the wire with impunity, though I would recommend that he wear the proper fall arresting gear.
lots of lamps have their switch on the cable, so the portion between the switch and the lamp works exactly as the switch controlled-outlet. so the parent is right : as long as the lamp is off (=the loop isn't closed) Mr. Rabbit is safe. And if he managed to short the exposed wires during his meal, you're going to discover some sparkling surprise next time you turn on the switch.
Except that he's talking about a refrigerator and specifically said appliance not lamp:
My aunt's rabbit chewed through her refrigerator power cable twice, and one of my rabbits, before she was no longer allowed to roam the house, chewed every cable off the back of a computer (all low-current save the power cable) on two occasions. Thing is: if the appliance isn't drawing power right then, they can chew through with impunity
I've never seen a refrigerator with an inline switch in the power cord.
Thing is: if the appliance isn't drawing power right then, they can chew through with impunity, and even if it *is* drawing power, as long as they only chew through one wire at a time they'll just get a quick shock when they cut that wire. And given how dry a rabbit's mouth is, and that it's cutting through with its non-conductive teeth, they might not even notice.
That's not how electricity works -- the hot wire is hot regardless of whether or not the appliance is drawing power.
There are 3 wires in your refrigerator's power cord -- the ground wire (which the rabbit can suck on all day with no ill effect), the neutral wire, which is bonded to the ground wire at the distribution panel, so it should be at the same potential as the ground wire in a properly wired house, and the third wire is the hot wire. This is the one with the juice and the one that will cause a shock regardless of whether or not the appliance is running or not.
Of course, in an outlet controlled by a switch, the hot wire will not be energized if the switch is off (again assuming a properly wired house - some amateur electricians have been known to put the switch on the neutral side).
I don't get it -- RIAA claims to lose 12 billion dollars a year due to piracy. If the Google API helps them recover a tiny fraction of that amount, then it's worth the few million dollars/year they are estimating the API costs would be.
It seems almost as if they think that there is not as much piracy out there as they claim!
Are you really trying to link an event that happened 150 years ago to modern epidemiology? Doctors in the 1850's still practiced trepanation to cure a variety of ills...I think a lot has changed since then, including the role of doctors in collecting medical statistics.
Like the grandparent poster said, a lot of today's injury statistics come from the insurance companies.
If there are no mechanical linkages between the ICE and wheels, it becomes possible to swap the ICE (or ICE and generator) for something different. Such as a fuel cell. Or a different and better ICE.
Who would do that? Engine technology seldom improves quickly enough to justify swapping out an engine to get better efficiency, it's generally cheaper and easier to buy a new car that's been engineered to take advantage of the new technology.
Even ignoring connecting to the transmission, an engine (or fuel cell) is typically not a self contained unit that you can just bolt into an existing car, there are all sorts of mechanical, electrical, and fluid linkages that have to be made with the car itself.
I have a 15 mile commute (each way), and rarely am able to reach speeds of 70mph on my way to work -- 35 - 45 is more typical.
The Volt would give me an all-electric commute, yet I can still drive it 200 miles to Tahoe on the weekends.
The all-electric Leaf will give me around 70 miles of range, so no long weekend trips.
The plug-in Prius (official version, not aftermarket conversions) would give me around 15 miles of all electric range.
I fail to see the controversy - most people can have an all-electric commute with the Volt. It was already known that the ICE engine would kick in to supplement the battery, the fact that it supplements via mechanical connection in addition to charging seems immaterial.
Right, I understand that Google can't fork openJDK and do what they want with it, but since they didn't do that and claim to have written their JVM from scratch, how do you compute damages against a product that is available for free, source code and all. If anything, Android promotes Java and makes it more popular, so I fail to see how Oracle can claim that it damages them?
If Oracle is actively supporting a free open source, implementation of the JDK, how does this affect their case with Google? how do they claim damages for a product that is available for free?
But as I pointed out in my other post, it's hard to move potable water. In fact, it might be easier to run a desalinization plant. To ship in bulk you need either an ice berg (which has been proposed) or a purpose built tanker. So far, at least, the economics of water just haven't risen to the point where putting a whole bunch of money in for a tanker makes sense. Maybe later, but not as of 10/10/10.
This may come to some surprise to you, but I just read an article where a company plans to ship water using oil tankers!
If all goes according to plan, 80 million gallons of Blue Lake water will soon be siphoned into the kind of tankers normally reserved for oil and shipped to a bulk bottling facility near Mumbai.
Nothing in there about icebergs or custom built tankers. If you want to check out the article, scroll up to the top of this page and follow one of the links.
Slashdot Mirror
I forgot to answer your point about the phones:
Along those lines, I would think that if "ethical" and "security" are a problem, having valuable data on a phone is downright stupid. How many people lose their phones? I happens all the time.
My Blackberry is protected by a passphrase and auto-locks after 30 seconds of inactivity. (which is set by BES policy, it's not something I can configure).
The data stored on the phone is encrypted.
If someone picks up my phone, they have 8 guesses at the passphrase before the phone wipes itself. As soon as I report the phone lost/stolen to my IT department, the phone will be wiped remotely (or will be wiped the next time the phone is on the cellular network).
I'd say that someone has a better chance of getting to my secret data by stepping into my office when I step out (5 minute auto-lock timeout on my desktop and no disk encryption) than getting to it from my phone.
As other posters have pointed out, there are valid reasons to be cautious about the cloud. He's not saying "ethical" as in immoral, but ethics as in a professional responsibility to protect client data.
Until a cloud service takes the blackberry approach where the only person that has the key to decrypt the data stored on their server is the customer himself, Cloud services will have a hard time assuring customers that their data is secure and won't be inadvertently released to another customer. (not to mention the case where a cloud employee accesses the data).
Even something seemingly innocuous such as mail envelope information may be protected under various data protection laws. A breach of data could be financially devastating to an organization that's covered under these laws. (PCI, HIPAA, DoD security levels ,etc). Even data that is not protected by law may be so valuable to the organization that they don't want it inadvertently shared with others in the cloud.
Even if the cloud service provider guarantees that the customer's data won't run on the same hardware as other customers, there's still a chance for cross contamination, like if the service provider accidentally restores a backup tape on the wrong machine, or an employee copies a configuration file to the wrong server.
Is there a cloud email provider that allows for on-disk encryption? (I'm not talking about PGP encrypting all of my messages so even the recipient can't see them without decrypting, but I mean storing the data encrypted on disk and not decrypting until it's on my device).
I've known people that are that paranoid, and they work in healthcare and their job is to comply with HIPAA.
Isn't Wifi last decade too? And Bluetooth. You're so archaic, my next phone will connect to the net via TCP/IP: "Traditional Carrier Pigeon Internet Protocol". Latency sucks, but bandwidth is incredible. I've seen theoretical transfer rates in excess of 1Gbit/second (with latency in the 1 hour range, depending on your distance from home).
I don't treat my phone as a little computer with much the same capabilities as my big computer because it's lacking the screen and keyboard that my computer has. If I want a document on my phone, I just email it to myself. Am I supposed to explain to my mom how to STFP her recipes to phone?
For most small businesses their data is safer in the cloud than on their own servers (though the original article submitter is likely savvy enough to keep their servers patched and secure).
I tried to convince a small non-profit that they should move to Google Docs to get calendaring and access to files from home. They refused, saying "We don't trust them with our email and documents, what if hackers broke in". Yet they were using their ISP's POP3 mail server for email with no password encryption, and their office "fileserver" was the receptionist's computer and the whole reason I was visiting them was to help clear malware off that computer when their ISP threatened to cut off their internet service because that computer was part of a botnet and sending out spam.
Yet Google is "too insecure" for them.
If you have ethics and security issues with storing data in the cloud, then shouldn't you also be looking for a device or application that encrypts sensitive data?
Do any Android phones do encryption natively? I've heard that the upcoming Droid Pro claims to. I know the iPhone has encryption support, but I don't know how whether it encrypts all application data or only data that Apple deems 'sensitive'.
The point isn't that you personally can see the source code (unless you're a developer), but that others can see it and extend and enhance the product.
Most people don't value open-source in home appliances, but If you had an open source (and flashable) alarm clock, and if you hate that the snooze is always a constant 9 minutes, it's likely that someone else thought the same thing and released a patch to lat you set the snooze to whatever you want.
Likewise, if you have an android phone and hate that it doesn't support your VPN at work, you can bet that someone else had the same problem and ported a Cisco compatible VPN client to it.
The destruction would have been far less than that of Nagasaki or Hiroshima, since it would have detonated on the ground, instead of high in the air over the cities in Japan.
I wonder if that's what that other guy meant when he said this:
And that bomb detonated at an altitude of 500m to maximize destruction. An accidental surface detonation in an airplane crash is going to have a much smaller destructive zone, even though the bomb is twice as powerful. So even if that bomb had detonated in the crash, there would be survivors even on the airbase itself.
A an accidental detonation from a bomb twice the size dropped on Japan would not result in " immediate death toll" that " may have reached six figures".
In 1950, the population of Fairfield was around 3000. I don't know the size of the air force base, but I don't think it was close to the 6 figure range (today it has 15K military and civilian workers, it may have been higher during the cold war). Suisun City today has a fraction of the population of Fairfield.
Just 3km from the hypocenter of the bomb dropped on Nagasaki, most structures withstood the blast and most people that were indoors survived the initial blast.
And that bomb detonated at an altitude of 500m to maximize destruction. An accidental surface detonation in an airplane crash is going to have a much smaller destructive zone, even though the bomb is twice as powerful. So even if that bomb had detonated in the crash, there would be survivors even on the airbase itself.
Even in a 1 megaton blast (50 times as powerful as the bomb dropped on Nagasaki) , there's a 75% survival rate just 7.5 miles from the blast.
http://www.pbs.org/wgbh/amex/bomb/sfeature/1mtblast.html
So even if a a 1 Megaton accidental detonation occurred in the NW corner of the base today, it wouldn't cause an immediate 6 figure death toll.
This, of course, this ignores the long term deaths and illness caused by radiation exposure.
Thank you! You're absolutely right, I used 100 * 10^9 instead of 100 * 10^12 for the capacitance so I was off by a factor of 1000 -- thanks for the correction!
That makes perfect sense, but I wish Eivind Eklund would elaborate on his comment that some places use two hots but no neutral. What are they hot in relation to? Just to each other? So it'd be kind of like an outlet with an isolation transformer? Is there any ground reference at all?
Aw, man, you're going to start being civil. Okay, me too.
I thought I was already being civil?
More generally, let's go over this from first principles.
1. You can't get electrocuted or feel a shock unless there is current flowing. I can't prove this one but it's what Wikipedia says too.
Agreed.
2. You can't have a current flow unless there is a potential difference. That's derived from Kirchhoff's mesh rule: the sum of the emf in a circuit is the sum of the potential drop in the circuit.
Again, no arguments here.
3. You can't have a potential difference if there is only one wire, because there's nowhere to establish a difference: there isn't a circuit, by definition.
I disagree a little here. You don't need two "wires", just two "conductors". It seems like it's only a distinction in semantics, but the distinction will become clear later.
4. As such, if you touch a single wire, there cannot be a current flow. (I'm neglecting the capacitance of a body, but I specifically noted that in the original post -- and that's what I measured with the Keithley, and it's negligible.)
You still haven't convinced me that a rabbit has no path to ground. I have no reason to disagree that in your lab with an insulating floor and insulated shoes that your body would conduct practically zero current to ground, but in the real world, electrical shocks and even electrocution can result from contacting a hot wire, no need to contact both hot and neutral at the same time.
Here's an example: http://www.cdc.gov/niosh/face/stateface/ca/92ca014.html
5. Cutting a single wire, regardless of its voltage, still does not provide a potential difference, as there is still no circuit.
I still don't see how cutting the wire matters -- the rabbit did not cut the wire (did it? Do they really chew through the wire? I assumed they just bite through the insulation). In any case, can we just throw #5 out since it has no relevance at all?
Let's review to my original post, just to make sure everything is covered.
I said: "if the appliance isn't drawing power right then" -- which means no current is flowing, which means the entire line is at the same potential. So, no potential difference, so no way for there to be any current flow.
Here's where you've lost me again -- regardless of whether the power is on, the hot wire will have a potential of 120V at all points along it, and the neutral will have a potential of 0V. (in reality, voltage drop of the wire will cause a tiny difference in potential along the wire (increasing as current draw increases), but not enough to be meaningful.
Likewise, I said "as long as they only chew through one wire at a time" meaning the rabbit does not establish a potential difference between two lines: the rabbit is at a high potential with respect to ground but there isn't a circuit, so no current can flow.
This is the source of our disagreement - I say that any animal on a normal household surface without special protective gear will have a path to ground. It may be conductive or it may be capacitive, but it's a path nonetheless.
Particularly if he's chewing a refrigerator power cord, since in most cases he's going to be touching the metal (grounded) frame of the refrigerator to gain access to the cord. After looking at my refrigerator, I don't see how a rabbit could reach the part of the cord near the floor without touching some part of the refrigerator.
Uhhh. Okay, explain this to me. Since I'm both an electrician and an electrical engineer you can use the fanciest words you want. I have a wire. It is connected to 110 volts. It is not connected to anything else, which is why I specified that it is *unloaded*. I cut it in half.
To be fair, you said you can lick the hot wire without danger of shock, not just cutting it. Obviously if you clip with wire with insulated wire cutters you'll be fine.
Your path to ground is through the ground. What kind of surface are you standing on? Is it clean or dirty? What kind of shoes are you wearing?
My shoes are surprisingly conductive -- if I put both feet on my stainless steel cabinet, I get around 30000 ohms of resistance from my fingertips to the cabinet according to my multimeter. So there's my path to the floor. The NEC says to treat the concrete surface that I'm on as "grounded", so there's my path to ground.
Are you sure you're an EE? You mentioned that only a few hundred thousand electrons might flow due to capacitance alone - do you know how vanishingly small that amount of current is? The human body will have around 100pF of capacitance to ground, how much current (and how many electrons) will flow to charge 100pF to +169V and then discharge and charge to -169V every cycle?
oh wait, it's been a while since I've done any real EE type math, but I seem to be getting an effective resistance of 26500 ohms for a 60 Hz signal through a 100pF capcitor, so enough current will flow through capacitance alone to give you a shock. Did I do my math wrong?
I have gotten shocked before from a lamp where the cord had frayed and let the hot wire touch the lamp body. I got shocked when I touched the lamp while standing on a dry wood floor wearing rubber running shoes. One does not need an obvious path to ground to get a shock from 120VAC.
Where are these places? I thought most modern wiring practices use a hot and neutral wire (where neutral is at ground potential). They don't always make a distinction between hot and neutral at the outlet since often the outlet is unpolarized, but there is still a neutral. I'll admit to being completely unfamiliar with most asian wiring standards.
Is there any bonding between the incoming power legs and ground? What is the potential between the two hots and ground?
That's not how electricity works. The hot wire is hot regardless, but if nothing is drawing power, you can cut the hot wire with impunity. You can grab it and lick it, and your body will run up to 110V but if there isn't a path to ground, there isn't any current flow. Here's a great video [youtube.com] about a guy who works on high voltage lines, who is crawling along an uninsulated million volt line, working on it, because there's no ground return path so he's fine.
Tell me again how we moved from a rabbit under a refrigerator to an electrical serviceman on a high tension wire who takes great pains to ensure he's not grounded when he touches it? I was not describing how electricity works in all possible conditions, but in the conditions given in the post. Are those similar conditions? Do you see *any* difference between the two situations?
Why don't you do an experiment -- walk up to your refrigerator outlet (which should have no GFCI to protect you), stick a screwdriver into the hot side and hold onto the metal shaft of the screwdriver and see what happens. It's likely that you'll feel a shock. If you're unlucky you could die.
Its only 'hot' to you if your body completes a circuit to ground. Its perfectly possible to cut a hot wire if there is no chance of the current going through you to ground. Its how high voltage linemen who repair high tension lines via helicopter do it. The problem occurs if they get too close to a mast ( which would form a ground circuit ), or the other 'cold' conductor.
Yes, you are right. I would like to amend my post to say:
If the rabbit is wearing proper protective gear, including insulating rubber shields over his teeth, a dental dam in his mouth to prevent saliva from wetting his teeth and tongue, rubber booties on his feet to insulate him from the ground, and a full-body rubber jacket to prevent any part of his body from contacting the floor, in those circumstances, the rabbit may be safe from electrocution if he chews through the hot wire. In normal conditions found in most homes, with the normal clothing typically worn by rabbits, he'll likely provide a good enough path to ground to feel a shock when he chews through the hot wire.
Oh, and if the rabbit happens to be in a helicopter that is properly bonded to the power line...in those conditions he may also chew through the wire with impunity, though I would recommend that he wear the proper fall arresting gear.
lots of lamps have their switch on the cable, so the portion between the switch and the lamp works exactly as the switch controlled-outlet.
so the parent is right : as long as the lamp is off (=the loop isn't closed) Mr. Rabbit is safe. And if he managed to short the exposed wires during his meal, you're going to discover some sparkling surprise next time you turn on the switch.
Except that he's talking about a refrigerator and specifically said appliance not lamp:
My aunt's rabbit chewed through her refrigerator power cable twice, and one of my rabbits, before she was no longer allowed to roam the house, chewed every cable off the back of a computer (all low-current save the power cable) on two occasions. Thing is: if the appliance isn't drawing power right then, they can chew through with impunity
I've never seen a refrigerator with an inline switch in the power cord.
Thing is: if the appliance isn't drawing power right then, they can chew through with impunity, and even if it *is* drawing power, as long as they only chew through one wire at a time they'll just get a quick shock when they cut that wire. And given how dry a rabbit's mouth is, and that it's cutting through with its non-conductive teeth, they might not even notice.
That's not how electricity works -- the hot wire is hot regardless of whether or not the appliance is drawing power.
There are 3 wires in your refrigerator's power cord -- the ground wire (which the rabbit can suck on all day with no ill effect), the neutral wire, which is bonded to the ground wire at the distribution panel, so it should be at the same potential as the ground wire in a properly wired house, and the third wire is the hot wire. This is the one with the juice and the one that will cause a shock regardless of whether or not the appliance is running or not.
Of course, in an outlet controlled by a switch, the hot wire will not be energized if the switch is off (again assuming a properly wired house - some amateur electricians have been known to put the switch on the neutral side).
I don't get it -- RIAA claims to lose 12 billion dollars a year due to piracy. If the Google API helps them recover a tiny fraction of that amount, then it's worth the few million dollars/year they are estimating the API costs would be.
It seems almost as if they think that there is not as much piracy out there as they claim!
How can it be a serious calculator without RPN? Any idea if it will be programmable enough to implement RPN? Maybe with an alternate boot ROM?
Are you really trying to link an event that happened 150 years ago to modern epidemiology? Doctors in the 1850's still practiced trepanation to cure a variety of ills...I think a lot has changed since then, including the role of doctors in collecting medical statistics.
Like the grandparent poster said, a lot of today's injury statistics come from the insurance companies.
If there are no mechanical linkages between the ICE and wheels, it becomes possible to swap the ICE (or ICE and generator) for something different. Such as a fuel cell. Or a different and better ICE.
Who would do that? Engine technology seldom improves quickly enough to justify swapping out an engine to get better efficiency, it's generally cheaper and easier to buy a new car that's been engineered to take advantage of the new technology.
Even ignoring connecting to the transmission, an engine (or fuel cell) is typically not a self contained unit that you can just bolt into an existing car, there are all sorts of mechanical, electrical, and fluid linkages that have to be made with the car itself.
I have a 15 mile commute (each way), and rarely am able to reach speeds of 70mph on my way to work -- 35 - 45 is more typical.
The Volt would give me an all-electric commute, yet I can still drive it 200 miles to Tahoe on the weekends.
The all-electric Leaf will give me around 70 miles of range, so no long weekend trips.
The plug-in Prius (official version, not aftermarket conversions) would give me around 15 miles of all electric range.
I fail to see the controversy - most people can have an all-electric commute with the Volt. It was already known that the ICE engine would kick in to supplement the battery, the fact that it supplements via mechanical connection in addition to charging seems immaterial.
Right, I understand that Google can't fork openJDK and do what they want with it, but since they didn't do that and claim to have written their JVM from scratch, how do you compute damages against a product that is available for free, source code and all. If anything, Android promotes Java and makes it more popular, so I fail to see how Oracle can claim that it damages them?
If Oracle is actively supporting a free open source, implementation of the JDK, how does this affect their case with Google? how do they claim damages for a product that is available for free?
But as I pointed out in my other post, it's hard to move potable water. In fact, it might be easier to run a desalinization plant. To ship in bulk you need either an ice berg (which has been proposed) or a purpose built tanker. So far, at least, the economics of water just haven't risen to the point where putting a whole bunch of money in for a tanker makes sense. Maybe later, but not as of 10/10/10.
This may come to some surprise to you, but I just read an article where a company plans to ship water using oil tankers!
If all goes according to plan, 80 million gallons of Blue Lake water will soon be siphoned into the kind of tankers normally reserved for oil and shipped to a bulk bottling facility near Mumbai.
Nothing in there about icebergs or custom built tankers. If you want to check out the article, scroll up to the top of this page and follow one of the links.