• Joachim Otahal (unregistered) in reply to Steve the Cynic
Steve the Cynic:
Actually, there is British running 240+/-10 and Continental running 220+/-10 both of which conform to the EU-wide standard of 230+/-20... The plugs are not compatible, even if the equipment is.

The plan to make whole Europe to 240 has been running for quite a while now (quite over a decade I think). They swith to 240 in small steps over many years. Currently "the continent" is at 234 V with regulation precision +- 2V at worst. Usually you have less than +- 0.5 V difference. But the 220 V is still written on many devices, but most modern have "220-240" written on them.

• Tharg (unregistered)

Folks,

I have to call BS on a few things here. First of all, most equipment that is expected to be able to work in numerous countries uses switch-mode power supplies (PSU). If adequately specified, and I do emphasise the "if" in that statement, plugging a U.S. based PC into a U.K. 240 Volt outlet presents no problem, other than plug form factor. The very nature of a switch-mode PSU protects both user and equipment.

There is no way to switch between voltages, so the story in that regard MUST be BS. A switch, by definition makes and/or breaks a circuit. It has no effect whatsoever on voltage. Switches which do this are usually referred to as molten lumps of metal, since by dissipating power in themselves, by ohms law, they inevitably melt. For this reason, power engineers have always strived to reduce switch dissipation to an irreducible minimum. For those of a truly geeky bent, look up GTO Thyristors, and see what google reveals.

Third, in the U.K. there is no such thing as a 120 volt outlet. Step-down transformers may be used, but these are as common as rocking-horse droppings.

Fourth (or whatever, it's late here) Ohm's law states that voltage is proportional to current and resistance, which is used to deduce the ubiquitously famous V=IR. Some previous posters have noted that electrical engineers (such as I) use the symbol j for current, instead of i. Mathematicians originally developed complex numbers using i, but this is very confusing for EE's, who universally use i as the symbol for current.

This is why I call BS on V=IR, because it assumes a unity power factor, i.e. a purely resistive load. Anyone who believes that a switch mode PSU is purely resistive has been smoking herbal tobacco.

V=IR is only true for direct current. For alternating current, such as is used EVERYWHERE in the world for power distribution, this is utter bollocks. The equation should be V=IZ where Z is an impedance, and not a resistance.

By definition, an impedance is the vector sum of resistance and reactance, which yields an impedance.

Finally, I plead with so many folks who obviously know far more than I about all things software, to practice what they preach, and refrain from making ill-informed comment about such apparently innocuous things as electrical installations.

In the U.K. the 17th Edition of the wiring regulations is a weighty tome, for reasons which this thread makes self-evident.

• (cs) in reply to anon
anon:
What would happen if the set the switch on a PSU to 240V but plugged it into a 120V outlet?

Consider your hand-held electronic game with run-down batteries. Gets flaky, right? Usually the same thing.

Damage is possible but unlikely. (Though I once saw a computer terminal fail due to being run on a low voltage.)

• Joachim Otahal (unregistered) in reply to electric knownothing
electric knownothing:
What are the (dis)advantages of 220v vs 110v. Safety maybe if you get electrocuted (though 220 is still pretty safe, i experienced myself), but are there any technical debatables to not standardise?
The main advantage is that you can get more power through the same diameter wire. In Germany there is usually one fuse per room (living room) or one fuse for two rooms (sleeping rooms). Kitchen stuff like an oven or other special devices have seperate fuses.

With higher voltage you can transport the double energy with the same current, so the wire and plug does not heat up that much if you need 1000 W in 220V compared to 110V. For PC power supplies: The efficiency is better at 220V, usually about 5% better, less heat from the power supply. With the normal 16A fuses here you can draw 3300 Watt without problems, though real 3000 W devices are rare, 2000 W are common for electrical room heaters.

Now if you take the current way electricity is done in the US (I've seen the normal wiring, a nightmare compared to Germany standard) 220 V would be really a problem, billions of transformators would blow up within seconds or short circuit instantly, especially those which are "a bit" defective, but the defect does not show up at 110V. A lot of houses would burn.

As far as touching 220V to 110V, there is a difference, but not as bad as you may think (guess how I know). You should keep one hand in the pocket anyway when working on power outlets if you are not 100% sure they are without power.

• Azarien (unregistered) in reply to uzytkownik

Except that I used to have 230 volts BEFORE the change, and have 240 V now. Nothing blew up in my house, but some complaints in the neighbourhood were heard--usually involving old Soviet-made equipment designed for 220.

The plugs were not changed during the 220->230 change. Perhaps the most annoying power-related problem in Poland is that some old 2-wire plugs (the round ones) don't fit into 3-wire receptacle. Unless you "fix" the plug in a WTF style, by using a drill.

• Joachim Otahal (unregistered) in reply to anon
anon:
What would happen if the set the switch on a PSU to 240V but plugged it into a 120V outlet?

At first: Not much, either it does not give enough power to the PC or it works. But if it works and you operate it longer it will fail due to overheat of parts. It needs the double current from the wall outlet to generate the same voltage, in reality lot more than double since the circuits are calculated for that voltage. And higher Amps = more heat.

This usually applies to CHEAP power supplies, only those have such switches since it is cheaper that way.

• Tharg (unregistered)

Since power is proportional to the square of current, as always, voltage in power distribution should be high, and current low.

This is why in the U.K. power is transmitted at 400 or 275 KiloVolts, and not just volts.

I repeat, if you know not of which you speak, please do not speak, as this may endanger folks who trust such advice.

• (cs) in reply to JoJo
JoJo:
Since the guys come form the US, how would they be able to plug in if they forgot their power adapters as the article says - their plugs wouldn't fit into European sockets.
Rootbeer:
A quick skim of http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets doesn't turn up any plug designs which are physically compatible but use different voltages regionally.

Either this story has been anonymized past the threshold of plausibility, or the electrical WTFs in that warehouse are even worse than imaginable.

Plug-in adapters may have been in use. They convert the physical plugs, but don't change voltage. So US plug - adapter - UK socket normally gets 240 volts (boom boom for most things). But change the building power to give 120 volts to the circuit and all is fine (and a UK device expecting 240 plugged into an outlet giving 120 will just work slowly or not at all, it won't be destroyed).
• Azarien (unregistered) in reply to Rick
Rick:
Not that it would ever happen, but if the US were to convert to 220v for household current there would be many deaths, while all 3 parties were educated.

That would be very complicated thing to do, as all the installations in every household would have to be rated or replaced for the higher voltage. It's like railway gauge or right and left-hand driving: whatever you have in your country, you are stuck with it for good. As for the "more careful" thing: I don't know how does 110V feel like, but if an electrician is careful enough to never, ever touch a live wire, it doesn't matter what voltage he works on. I got shocked with 220 volts several times. A short accidental exposure won't kill you. Probably.

• Smokin' Jo (unregistered) in reply to Tharg
Tharg:
Folks, <snip> Anyone who believes that a switch mode PSU is purely resistive has been smoking herbal tobacco. < snip>

Hey Grumpy, isn't all tobacco herbal?

• AA (unregistered)
There is no way to switch between voltages,

Because having a switch that connects the circuit to either a 110V or 240V source is somehow impossible.

• Joachim Otahal (unregistered) in reply to Tharg
Tharg:
This is why in the U.K. power is transmitted at 400 or 275 KiloVolts, and not just volts.
One thing that was in the news a few days ago: China bought a few 800 kv DC tranformators from Siemens-Germany to transport the electricity from their windparks to the cities. (For those who ask why DC instead of AC: If the cable is VERY long DC is the way to keep losses down).

Look at the pictures from http://w1.siemens.com/press/de/pressebilder/?press=/de/pressebilder/bilder-photonews/2009/pn200917.php --

Remove the humans from the pictures that transformator looks like a 20 cm (8 inch) playmobil child toy.

http://w1.siemens.com/press/pool/de/pressebilder/power_transmission/300dpi/ept200810001-01_300dpi.jpg

http://w1.siemens.com/press/pool/de/pressebilder/2009/photonews/300dpi/PN200917/PN200917-02_300dpi.jpg

• AA (unregistered)

Someone needs to shop some lego figures in place of those people.

• Joachim Otahal (unregistered) in reply to AA
AA:
There is no way to switch between voltages,

Because having a switch that connects the circuit to either a 110V or 240V source is somehow impossible.

That is irony right? Those switches are real, the mechanics of those switches is very simple. Even if you do not use one common cable those switches are simple mechanics. A sewing machine is mechanically more complex by a few magnitudes, even the most simple watches which use analogue display instead of digits is a lot more complex.

• Loveknuckle (unregistered) in reply to Mike D.
Mike D.:
A power supply set to 120V but plugged into a 240V main doesn't look like a short circuit to the 240V main until it fails short, which is after it burns up.
You said "but plugged".
• (cs) in reply to Joachim Otahal
Joachim Otahal:
With the normal 16A fuses here you can draw 3300 Watt without problems, though real 3000 W devices are rare, 2000 W are common for electrical room heaters.
In Britain 3 kilowatt kettles are pretty common. The speed difference when boiling is noticable, and a quicker boil leads to less heat lost.
• Shinobu (unregistered)

Any system which tolerates not a single error and requires constant and perfect human vigilance to avoid catastrophe is deeply flawed.

Joachim Otahal:
With the normal 16A fuses here you can draw 3300 Watt without problems, though real 3000 W devices are rare, 2000 W are common for electrical room heaters.

I'm not sure where you are, but at least in Sweden, the common fuse size to use is 10 A (hence the 2 kW "border" you've noticed). Although the schuko plugs would handle 16 A without a problem, going up from 10 A to 16 A means switching from the minimum cable size (1.5 mm^2 area per conductor) to the next one (2.5 mm^2) in the wall cabling. Usually, only the stove necessitates using that cable dimension (and it also usually wants three-phase supply, so it's still a special case). Hence usually all wiring is made for 10 A, except the stove circuit and possibly some additional special equipment outlet.

Joachim Otahal:
With the normal 16A fuses here you can draw 3300 Watt without problems, though real 3000 W devices are rare, 2000 W are common for electrical room heaters.

I'm not sure where you are

South-West Germany. Here you can find 10A wiring only in old houses with old electricity (30+ years).

• Tharg (unregistered)

Not so RLS, VOLTAGE is the way to keep losses down, not current.

Long distance transmission of significant power is fraught with difficulties using alternating current (A.C.) For example, there is a 2 Gigawatt interconnect between England and France, and it uses direct current (D.C.) If A.C. is used, then it is necessary to synchronise both systems otherwise oscillatory currents develop, which fry the transmission system. Thus, to avoid England trying to force the whole of Europe to its frequency (via the interconnect) and/or the whole of Europe trying to drive England to its frequency, D.C. high voltage transmission is used, thereby decoupling the two systems.

The higher the voltage, the more efficient the transmission. Thus 800 K.V. is superb, and was chosen because of the long distances involved, and the need to decouple systems. It would be more efficient if we all transmitted power at say 10 Megavolts, but you will find it difficult to find insulators that can cope with this at your local hardware store (or anywhere for that matter).

There is little or no connection between long-distance H.V. power transmission and that which emerges from a wall socket near you. There are hordes of transformers between you and the 400 (or even 800) K.V.

• Tharg (unregistered)

Not so RLS, VOLTAGE is the way to keep losses down, not current.

Long distance transmission of significant power is fraught with difficulties using alternating current (A.C.) For example, there is a 2 Gigawatt interconnect between England and France, and it uses direct current (D.C.) If A.C. is used, then it is necessary to synchronise both systems otherwise oscillatory currents develop, which fry the transmission system. Thus, to avoid England trying to force the whole of Europe to its frequency (via the interconnect) and/or the whole of Europe trying to drive England to its frequency, D.C. high voltage transmission is used, thereby decoupling the two systems.

The higher the voltage, the more efficient the transmission. Thus 800 K.V. is superb, and was chosen because of the long distances involved, and the need to decouple systems. It would be more efficient if we all transmitted power at say 10 Megavolts, but you will find it difficult to find insulators that can cope with this at your local hardware store (or anywhere for that matter).

There is little or no connection between long-distance H.V. power transmission and that which emerges from a wall socket near you. There are hordes of transformers between you and the 400 (or even 800) K.V.

I'm posting this comment to see what timezone the comment timestamps are using. :D

• (cs) in reply to Coyne
Coyne:
frits:
I call BS. There is this thing called a fuse in every piece of electrical equipment that plugs into a wall outlet. For those of you who don't know, they are designed to break the circuit before damage occurs from overcurrent conditions.

Fuse slooooooowwwwww. Overvoltagedamagereallyfast!

This diagram shows that a 20A "fast-acting" fuse can carry 100A for up to 0.1 seconds before blowing.

So the power supply is long dead before the fuse can react. A capacitor can blow after 1/2 cycle of current (0.008 second)...it only takes that one pulse of voltage over the capacitor's rated maximum, and it's toast.

The fact that you chose a 20 Amp Bussman fuse as a line fuse for a PC invalidates your post.

Addendum (2010-01-06 08:39): I'd like to know where you get this from :

"A capacitor can blow after 1/2 cycle of current"

Most capacitors can take several seconds of gross overvoltage before overheating and failing. The voltage rating for capacitors has a built-in safety factor and is specified for continuous use.

• AA (unregistered)
That is irony right?

Sarcasm, actually. You'll notice I was quoting Tharg@294872.

Captcha: haero (We don't need another haero...)

• EE Bob (unregistered) in reply to nB

Really? Strange, as an electrical engineer, I've never seen anyone use E for volts. Ever. Not in industry or during my degree.

• Fred (unregistered) in reply to frits
frits:
Coyne:
frits:
I call BS. There is this thing called a fuse in every piece of electrical equipment that plugs into a wall outlet. For those of you who don't know, they are designed to break the circuit before damage occurs from overcurrent conditions.

Fuse slooooooowwwwww. Overvoltagedamagereallyfast!

This diagram shows that a 20A "fast-acting" fuse can carry 100A for up to 0.1 seconds before blowing.

So the power supply is long dead before the fuse can react. A capacitor can blow after 1/2 cycle of current (0.008 second)...it only takes that one pulse of voltage over the capacitor's rated maximum, and it's toast.

The fact that you chose a 20 Amp Bussman fuse as a line fuse for a PC invalidates your post.

Fuses, and Circuit Breakers, are designed to stop your house from burning down, and killing everyone in it.

They do this by interrupting the current before the wires get so hot that your wall catches fire.

In this example, the circuit breakers worked correctly. The factory did not burn down, and no one was burned to death.

• Teacher (unregistered) in reply to Fred

The typing teacher came in and started turning on the computers.

The first one went BANG and failed. The second one went BANG and failed. The third one went BANG and failed.

This sequence reduced the typing teacher to a quivering wreck.

As a result of this episode, I super-glued all the voltage setting switches into the 230 position.

• expat (unregistered) in reply to uzytkownik

Be glad you don't work in countries where the power system is truly screwed up. I deal with IT for a company in Saudi Arabia, where the wall sockets generally let you plug in UK, US, EU, and Australasia plugs, and where you get either 110 or 240, depending on where you are, how old the building is, and the mood of the electrician who wired it up.

• Paul (unregistered)

All the people calling BS:

• 110/120V is actually quite common in the UK - look on any building site, you'll see lots of yellow boxes (eg http://www.screwfix.com/prods/32327/Electrical-Supplies/Industrial/110V/1-5kVA-Power-Tool-Transformer)

These are used (a) because 110V is supposedly safer than 240V, and also (b) they are isolating transformers, thus reducing the risk of circuits to ground via a builder and (c) it lets companies charge more for construction equipment.

I suspect the factory the OP's company had just moved into already had humungous 240->120V transformers for (supposed) safety purposes.

• the person saying that "you can't switch between 240 and 120V" has obviously never heard of a DPDT switch (or maybe two DPST switches for added danger). I'm not saying it's sensible or safe, but it's certainly possible.

• I did an Electrical Engineering degree, and I don't remember using E instead of V anywhere (we did inconsistently use j instead of i though (depending on subject - maths used i, electromagnetics used j)).

• Fuses on UK mains plugs are definitely for protecting the wire. Yes, 1mm flex may not 'fuse' at 32A, but it will get very hot - this could cause a fire, especially if the flex is coiled or hidden under carpet or something. This is the reason that UK plug fuses are rated at 3A, 5A, 13A only - those are the common cable capacities. These fuses are also slow-blow fuses. For equipment protection, there should be a separate internal fuse, which can be rated much lower than 3A, and can be a quick- or slow-blow as appropriate.

Often low cost equipment (eg computer PSUs) aren't separately fused because if it blows up you just have to buy a new one, which is obviously to the benefit of the manufacturer. Also, in most circumstances, an interior fuse blowing would normally suggest an equipment failure, and who repairs computer PSUs?

• Not really related - but a wiring WTF. UK wiring has a nice system called the 'ring main' which isn't used in most other countries - it's used here because it uses less copper than the more common radial system (copper was in short supply during the war). However it's very dangerous because it can fail in an almost undetectable, but dangerous state (ie a broken ring, where everything still works, and the MCB will blow at 32A, but the cable can only handle 20A).

Other countries try to get a similar risk by not putting fuses on mains plugs, so they aim to get their fires by running 16A over 0.5mm flex.

• (cs) in reply to m0ffx
m0ffx:
Plug-in adapters may have been in use. They convert the physical plugs, but don't change voltage. So US plug - adapter - UK socket normally gets 240 volts (boom boom for most things). But change the building power to give 120 volts to the circuit and all is fine (and a UK device expecting 240 plugged into an outlet giving 120 will just work slowly or not at all, it won't be destroyed).
Most electronic equipment these days uses a switch-mode PSU, which (normally) copes very nicely with whatever domestic-level AC you throw at it. (It costs about the same to make PSUs that work everywhere, and doing so increases the number of countries the manufacturer can sell to.) Hardly anyone uses systems based on transformers any more; the little switches mentioned in the article have been old hat for years, and I think the last PSUs for which they were common were for AT cases. (I can remember buying one about 7 years ago, and being told that it was rather old hat and asked was I sure; I was, as I was reviving an old machine.)

It's the non-electronic equipment that's more of an issue. Lighting and anything that draws heavy current (heaters, larger motors) needs to be rated for what's installed. Luckily, most of that sort of stuff doesn't get moved around by consumers between different countries all that much.

• Red October (unregistered)

Paul's point above is half of what I was going to say. Being that tons (tonnes?) of power tools and such require 110V, and that if you want it, the power company can bring in just about any kind of power you want (Due to old equipment, I believe in NYC DC is still supplied to some factories!) if you're willing to pay for it, it would not be surprising to learn that the factory had if not a direct feed of 110V from the power company, that it had a huge on-site stepdown designed to run heavy-duty tools. The wiring was dodgy to begin with, it's also no surprise that the factory dudes would ghetto-rig the wiring however was convenient, or even that such a system was designed deliberately for a factory so that "normal" and 110V equipment could be used in a location as needed, and while this was acceptable in a factory setting, it was verboten in an office. Either way I've seen some nearly as bad WTFs in my experience.

I used to work in a Radio Shack, with a wonderful gentleman from Kenya, who was educated in England. I did nearly shit bricks when he sold someone a power converter for a journey to england and went about telling them to use the Europlug-type converter and a screwdriver or something to open the shutters on the BS-1363 socket and jam in the round-pin plug! It works but I wouldn't trust a tourist to do it!

Another curiosity is that certain common American 220+ plugs are wired as Phase/Phase/Return (The common plugs for clothesdryers and stoves) with two 120V lines and a common return. The motors and lights will run off a single 120V phase, as the drum motor doesn't need to be very strong, and 240V lamps would be a pain to find, but the heating elements will use both phases together. These sockets have no earth, and are "earthed" through the return! There are even obsolete types which are simply two phases, but these are uncommon at best (I've seen a grand total of one in my life). This "split-phase" system is also how the European 110V power tools operate, hence the safety feature (only 55V between a phase and return). There are also four-pin sockets which have a dedicated earth, and "normal" Phase-return-earth sockets that deliver 240V for air conditioners, etc. Some equipment that expects phase-return will work on phase-phase of equal voltage, some will not. I'm not an electrician and can't say why this is, but it certainly complicates things greatly.

• Kaijuu (unregistered) in reply to gramie
gramie:
The real probably >100 years real WTF is - who designed 2 compatible plugs with different voltages? Shouldn't they be idiotproof?

In Europe there are 2 standards ('British' and 'continental') both running 230V.

Or Japan, where the eastern part is on 50Hz and the western part on 60Hz!

The only real problem I've seen is that some timers that are based on AC frequency have to have two sets of markings.

But still, it's just ignorant.

When visiting the Ueno Science Museum in Tokyo, I learnt that the history behind this is the fact that back when electricity in Japan was a novelty, the Tokyo power company bought themselves an AEG generator (German, thus 50Hz) and those crazy Osakans (doing just about everything differently compared to Tokyo) hopped on the General Electric-bandwagon from the US (thus 60Hz).

• (cs) in reply to uzytkownik
uzytkownik:
Steve the Cynic:
uzytkownik:
The real probably >100 years real WTF is - who designed 2 compatible plugs with different voltages? Shouldn't they be idiotproof?

In Europe there are 2 standards ('British' and 'continental') both running 230V.

Actually, there is British running 240+/-10 and Continental running 220+/-10 both of which conform to the EU-wide standard of 230+/-20... The plugs are not compatible, even if the equipment is.

Not quite. Some time ago Poland switched from 220 V to 230 V - and it was said it was to confirm EU standard - but IANAL/IANAE. Anyway my point was that *incompatible* voltages should have *incompatible* plugs (compatible voltages having incompatible plugs is a mere annoyance).

As mentioned before, there are tons of standards in Europe. All except the British standard (type G; used in the UK, Republic of Ireland, Malta and Cyprus) use the basic two round pins for live and neutral (type C), whilst for the earth there are at least four systems: the German, the French, the Italian and the Swiss. The French (type E) and the German (type F) systems can be made compatible with a hybrid plug.

(It's even worse for telephone plugs, where each country has its own system. Usually, plugs now use RJ-11 as a standard.)

But the British and the, eh, non-British systems are not compatible. Yes, they are both more or less 230 volts, but the British system allows for high-current ring circuits, and doesn't have a fuse box. Instead, the fuses are in the plugs. Connecting a continental socket to a British system without a fuse would be a bad idea.

Here in Malta, we have the British system, but get a lot of equipment from the continent. A biro, screwdriver or key are useful tools to force a type C plug into a socket.

• Dan (unregistered) in reply to Severity One
Severity One:
but the British system allows for high-current ring circuits, and doesn't have a fuse box. Instead, the fuses are in the plugs. Connecting a continental socket to a British system without a fuse would be a bad idea.

The amount of ill informed nonsense in here is staggering, even from self proclaimed electrical engineers.

Let's see...

• Of course we have fuse boxes in the UK.

• Yes the plugs are different, but the voltages are compatible across Europe.

• Overvoltage does not blow fuses, overcurrent does.

• You can switch between voltages with a switch, provided you have different voltage supplies available to switch between.

• A laptop style power adapter is 99% of the time rated for 110-250v so this whole story is bunk in at least some way.

• Changing voltage does not change the current.

• Yale (unregistered) in reply to Mason Wheeler
Mason Wheeler:
I'm thinking back to that conversation, and if I recall correctly, it might make more sense in context. We weren't talking about suddenly switching voltages like what happened here. The subject was, to deliver the same amount of electrical power, whether it would be safer to do so at 120 or 220 volts. He said that 220 was safer because it could deliver the same amount of power at a lower amperage, which is what actually determines whether or not a shock will cause real damage.

(To put it in context, if you rub your feet on the carpet and touch a doorknob and you can feel the static spark, that's somewhere in the tens of thousands of volts, if not hundreds of thousands. But it's harmless because it's just an infinitesimal fraction of an amp.)

Does that make any more sense?

No. If an electrician told you anything like this, he's a terrible electrician.

The problem is that the amperage delivered is a function of two things (well, three technically, but we'll get to that in a bit). Namely, the voltage supplied and the resistance across the voltage. According to Ohm's law, I=E/R. That is, current = voltage / resistance. However, voltage doesn't do anything on its own--you can't power a motor with just voltage. You need current, which is the actual flow of electrons, to do the work. So given an increase in voltage, you get a proportional increase in current for the same resistance.

Picture a pipe that carries water, but is filled with sponges. The width of the pipe would be the voltage, and the density of the sponges would be resistance. If you increase the width of the pipe, but keep the density of the sponges the same, you can get more water through the pipe. Similarly, if you kept the width the same, but thinned out some of the sponges, you can get more water through the pipe. But in the end, you're interested in how much water is flowing through the pipe, not how wide the pipe is or how many sponges are inside it.

So, how does this apply to electrical safety? Well, your body has a constant resistance. It's the same whether you're touching a 110 or 220 line. But if you touch a 220 line, twice as much current will potentially flow through your body as a 110 line, because the voltage is twice as high but the resistance is still the same. That is, the density of the sponges is still the same, but the pipe is twice the size.

You're correct that static electricity has an incredibly high voltage, and yet a very low current. This gets us back to that third limiting factor I mentioned above. If there are just not that many electrons available, as is in the case of static electricity, it doesn't matter how wide the pipe is or how dense the sponges are past a certain point. You could have a pipe with the cross section of Manhattan that contains a vacuum, but if you only have a single bucket of water available it's not going to have much effect. But since the power company can supply you with effectively unlimited electrons--at least until your circuit breaker trips--you're going to get twice the zap on 220 as on 110. Don't count on the circuit breaker saving you, though. As little as 1/10 of an amp across your heart is enough to do you in, and most circuit breakers don't trip until the current exceeds 15 or 20 amps.

BTW, if you're wondering what an amp is, 1 amp (short for ampere) represents ~6.242 * 10^18 electrons flowing past a given point in one second.

• (cs)
Dan:
Severity One:
the British system [...] doesn't have a fuse box. Instead, the fuses are in the plugs. Connecting a continental socket to a British system without a fuse would be a bad idea.
* Of course we have fuse boxes in the UK.

In fact we generally use trip switches instead of fuses in the "fuse box", and RCD trips are required on new installations now (they also trip if the difference between live and neutral is more than 30mA, aka more than 30mA is grounded somewhere).

• (cs) in reply to Dan
Dan:
The amount of ill informed nonsense in here is staggering, even from self proclaimed electrical engineers.

Let's see...

• Of course we have fuse boxes in the UK.
Ah yes, you're right. I just didn't recognise it as a fuse box, because the fuses look completely differently from the continental ones that I'm used to (which nowadays would be circuit breakers anyway).

I opened that fuse box once, to try to figure out how the cables were going, must have looked at it for the best part of a minute, and closed it again.

The person responsible for the electrical wiring in my house ought to be taken out and shot.

• CMMI Snob (unregistered)

I got frist! That's a blast.

• chl (unregistered) in reply to Mason Wheeler
Mason Wheeler:
The subject was, to deliver the same amount of electrical power, whether it would be safer to do so at 120 or 220 volts. He said that 220 was safer because it could deliver the same amount of power at a lower amperage, which is what actually determines whether or not a shock will cause real damage.

This still does not make sense. If you touch a hot terminal, the voltage (with respect to ground) at that terminal will determine the damage to your body. More voltage => more current through your body => more damage. It is irrelevant how much current also happens to be running through any other connected equipment.

Again, your body is not built to accept constant electrical power from an outlet. It has a certain electrical resistance, which means that more voltage will drive more current through your body, and it is indeed the current that does the damage. Rule of thumb: 1mA is noticable, 10mA are painful, 100mA are fatal.

Here you can find 10A wiring only in old houses with old electricity (30+ years).

Here, old buildings quite commonly actually have 6A fuses. Not sure if that's due to the minimum area changing or just "better safe than sorry".

• marc (unregistered) in reply to Kaijuu

TRWTF is that they used identical plugs for the two different voltages, while European plugs and US plugs are naturally different. They could have ordered in a few US style wall sockets and run those on 100 volts, and keep the EU stuff running at 240. As the sockets are incompatible with one another, that would've prevented all troubles altogether. (Likewise you're unlikely to plug industrial 360V plugs into a 240V socket or vice versa).

• (cs) in reply to Fred
Fred:
frits:
Coyne:
frits:
I call BS. There is this thing called a fuse in every piece of electrical equipment that plugs into a wall outlet. For those of you who don't know, they are designed to break the circuit before damage occurs from overcurrent conditions.

Fuse slooooooowwwwww. Overvoltagedamagereallyfast!

This diagram shows that a 20A "fast-acting" fuse can carry 100A for up to 0.1 seconds before blowing.

So the power supply is long dead before the fuse can react. A capacitor can blow after 1/2 cycle of current (0.008 second)...it only takes that one pulse of voltage over the capacitor's rated maximum, and it's toast.

The fact that you chose a 20 Amp Bussman fuse as a line fuse for a PC invalidates your post.

Fuses, and Circuit Breakers, are designed to stop your house from burning down, and killing everyone in it.

They do this by interrupting the current before the wires get so hot that your wall catches fire.

In this example, the circuit breakers worked correctly. The factory did not burn down, and no one was burned to death.

Line fuses inside equipment has nothing to do with house (factory) wiring.

• (cs) in reply to Mike D.
Mike D.:
I wish more companies switched to 85-240V supplies like Apple did in the late 80's, but that would have involved spending money.

Having worked at an overseas military base where we got a lot of 120V equipment from the states, a lot of 240V equipment from the economy, etc... I know the pain. I actually sourced buying universal auto-switching power supplies - I had a good arguement that, at \$10 more each, they were still cheaper than the inevitable bangs and 'at our expense' replacements. It was killed by my supervisor as 'well, we'll just TRAIN people not to do it better, that's even cheaper! (BANG!)'. Had to deal with 2 blown supplies that day.

My personal solution would be to have different outlets - 120V outlets for the executives and such, 240V ones for the others. Then label. We mostly blew power supplies because somebody would forget and use a 240V cord(IE cord intended for 240V outlet) on a PS set to 120V.

• (cs)

There's a machine that could do his job: http://www.youtube.com/watch?v=Z86V_ICUCD4

• (cs) in reply to Tharg
Tharg:
This is why in the U.K. power is transmitted at 400 or 275 KiloVolts, and not just volts.

Happens everywhere in the world. In the USA*, even homes get 240V, which is used directly for high power appliances like air conditioners.

Heck, it'd only take about an hour of working on my breaker box and a bunch of double pole breakers to convert my house completely to 240V. Standard building wiring is rated to like 600V, so that would work. Incompatible appliances would remain a concern, of course.

Considered this for my computers for the uptick in efficiency, but it's tough to find 240V surge supressors/UPS units of appropriate rating for a personal computer in the USA.

It can be done, but I'd pay a hefty premium.

*With a few exceptions. They finally shut off the last DC distribution grid in NYC like 10 years ago, after operating for like a hundred years.

• En fisk uten sykkel (unregistered) in reply to frits

Someone may already have replied to this post, but I'm lazy... :-P

It's at least plausible. As a teenager I once flipped the red switch next to the power supply (as pointed out on the image) on my computer before I plugged it into the computer, and it most certainly resulted in a big bang and a foul odor of burned components.

• En fisk uten sykkel (unregistered) in reply to En fisk uten sykkel

The last post was supposed to contain this quote.

frits:
I call BS. There is this thing called a fuse in every piece of electrical equipment that plugs into a wall outlet. For those of you who don't know, they are designed to break the circuit before damage occurs from overcurrent conditions.
• En fisk uten sykkel (unregistered) in reply to ih8u
ih8u:
Instead of having a sensible setup (like the adapters in your off-hand comment), you suggest certified electricians.

[ ... ]

Damn, time to switch to decaf.

You better switch sooner than later, because Yazeran certainly states:

Yazeran:
But I guess having a few spare adapters was too much for them....

• JuggaloBrotha (unregistered)

What I'm wondering is when someone will point out that it's 120v, 240v and 480v. A US house will run on 120v, a US factory is usually 120v and 240v for large equipment and 480v if 3-phase motors are involved.

Europe (and the rest of the world too) uses 240v in houses and factories with 480v in some factories.

• JuggaloBrotha (unregistered) in reply to En fisk uten sykkel
En fisk uten sykkel:
The last post was supposed to contain this quote.
frits:
I call BS. There is this thing called a fuse in every piece of electrical equipment that plugs into a wall outlet. For those of you who don't know, they are designed to break the circuit before damage occurs from overcurrent conditions.
Fuses and circuit breakers do the same thing, they disconnect the line when there's too much current passing through to protect the wiring. The difference is that fuses burn out to break the line and need to be replaced, a circuit breaker trips and just needs to be reset to allow power on the circuit again.