Standardization makes life easier, but it is often impossible to introduce it to systems that have a messy evolutionary history. Electricity supply is a case in point. [IEEE Spectrum]
Go just about anywhere in the world and you can charge your laptop with a simple adapter - yet take a USB cable and and it's anybody's guess whether it will work - even if you can physically plug it in.
Laptop charging cables come with AC adapters. USB cables are far more versatile than laptop charging cables in my experience. I am able to use a variety of USB cables if I lose one, and they’re available everywhere for much cheaper than a laptop charging cable and associated AC adapter, which most likely is not even available for purchase in most places.
Recently learned this the hard way. A Macbook will charge over any voltage over USB-C. Slowly, or maybe just increasing battery life, but it'll take anything. It'll charge from a 5V1A power bank if you like.
So when I had to make an emergency trip, I assumed my newish Dell with USB-C charging would be the same. And that assumption was false. Unless you're charging with 20V USB-C (not common outside of laptop chargers), it won't draw anything at all.
USB C is a nightmare. Everyone has basically decided that following the spec isn't worth it and there's shit everywhere. The connector is terrible for laptops, I have to be incredibly careful not to bend the connector and the cables wear out surprisingly quickly from connect/disconnect cycles.
I could accept different standards across the world - things evolve differently. But why should a country have multiple standards? That one drives me nuts. Here in Israel fine - we use Type C... except for the completely random use of Type H. Then, main room air conditioners use Type M - but at least that's standardized...except for when it isn't.
except, that it's not really type c. type c is bigger pins in general (so while it fits, it many times has to be forced in). I'm also a bit confused by the graphic of type-h. pretty sure type h is only used here? (which is a thing itself, why!?)
C is no ground and H does have
But what I've been seeing these days is C style pins, but with a ground
The M used in Israel might be different than the one pictured as it is used exclusively for 3 phase lines (so an AC that doesn't need 3 phase can then have a regular plug)
Our C is both ground and no ground. We have two prong and three prong type C, much like NA has two and three prong. Currently, the electricians I've spoken to say that we do indeed use an "M" (notice the quotes) because it's an Israeli M. Frankly.. it's quite silly.
> But why should a country have multiple standards? That one drives me nuts. Here in Israel fine - we use Type C... except for the completely random use of Type H.
Type C (the "europlug") is a compatibility low-amperage plug (2.5A @ 250V) for shavers and small lamps and USB power adapters and such. It was designed to be compatible with the high-power Type C, E, F, and K popular in mainland europe, but providing a cheaper plug, and allowing for dedicated low-amperage circuits (e.g. shaver sockets which would be safer in bathrooms).
Type H (and N, which is brazilian) were then designed to be compatible with the Europlug in turn.
> Then, main room air conditioners use Type M - but at least that's standardized...except for when it isn't.
Possibly rather than Type M (which is a 15A plug) it's the 30A plug from the same over-arching BS546 standard? Or a similar-looking 3-phase plug? That's what I'd expect for high-power applications like AC. I assume the standard Type H is 15 or 16A single-phase aka the usual mains.
For example the absurdly large UK plugs with integral fuses date to first (or was it postwar? I forget) surge of electrification which,for expediency’s sake was often point-to-point (like “party line” phones) so local devices needed protection. Nobody else went this route (well, excepting some dodgy informal systems I’ve seen in India and southern Africa) so could get away with smaller, less expensive plugs.
(And as for terminology, why do we plug the plug into the plug in Australia?)
Then surely shuko plug is the ultimate of both worlds? There is no need for the increased size and complexity with the internal fuse, and the socket is recessed so you can't touch the pins until they are way out to the connection points.
Yes, the Schuko is a good design. Probably the best, although it’s a bit inconveniently large for my tastes.
The modern US one (NEC) is probably the best trade off of size and safety (see my parallel comment on its physical design). Though I do think there is still too much use of two-prong plugs, despite the near ubiquity of grounded sockets these days.
I wouldn’t worry too much. The voltage is low. More importantly, the three prong (grounded) plugs have longer ground pins than the other pins, so the most electrically convenient return path will always be connected while any current is present.
You can’t see this structure in the standard diagrams such as the ones in the article but you can tell it for yourself by inspection.
Although it is extremely solidly built, it's mostly built for a different context: the UK mostly uses ring circuits (similar to a ring network) rather than the radial topology used pretty much everywhere else. This means there can't really be "small" fuses at the fusebox, you can't put a 16A fuse for the entire ring because that'd be the load for all the devices in the house.
As a result you need smaller fuses at the plug level. An advantage of that is that your fuses can then be sized specifically for the appliance cable, and thus you can safely use much smaller cable e.g. let's say that you want to design a 2.5A extension cable, you can put a 2.5A fuse in it and be safe. In a radial context where plugs are unfused, somebody could plug a 10A appliance on the 2.5A cable and melt the cable, the fuse only protects the "wall" circuit and won't blow until >16A (generally).
In fact this has been an issue in the US in the last few years: because of the low voltage, 20A circuits have become more common, but extension cords are still usually 16A. If you plug a 16A cord to a 20A circuit and draw 20A from it, the fuse will be perfectly happy (everything's fine as far as it's concerned) but the cord can catch on fire.
Anyway since they needed larger plugs for the fuse, I expect the UK standards body reinforced the plug while at it.
> If you plug a 16A cord to a 20A circuit and draw 20A from it, the fuse will be perfectly happy (everything's fine as far as it's concerned) but the cord can catch on fire.
Technology Connections recently
made a video about this.
I drove all my friends crazy in Singapore (has the same switched outlet) by never, ever “switching off the socket” - whenever a housekeeper did that it would take me a long time (initially) to figure out why an appliance wasn’t working.
Install some GFCI outlets everywhere and the risk is gone. Also you are very, very, very unlikely to be electrocuted in this way even if you do touch the metal and get voltage passed through you.
Like, it is possible, if one finger in a hand is touching the live prong, and another finger on the other hand is touching the neutral/ground prong, you'd pass current across your chest.
Or if you are touching something that is grounded, like a pipe/sink...
Further, the UK has twice the voltage which means twice the current will pass through you. The US 120v system is pretty safe in general. If you do something really dumb it'll kill you but 120v isn't really that concerning compared to 230-240. The cutoff for dangerous voltages is usually considered to be around 60v.
Yes, pretty much all european plugs are designed such that you can not connect the live before the ground is connected. In UK plugs, the connection of the neutral will also open the safety doors and allow connecting the live at all (that is not the case for mainland plugs, at least not the 7/7 ones).
With respect to UK plugs, it's also common for them to have the live pins only half exposed, with the rest being insulator, to avoid the possibility of touching live pins while the plug is partially inserted.
On the mainland the sockets tend to be recessed to work around the risk, but the "europlugs" (which are not grounded) almost all have this property as they can't really be "sealed in".
34 years in the US. I have never been electrocuted when plugging/unplugging anything. I dont know anyone that has been.
Wtf are you playing at? Everywhere across the planet has to adopt things that make you comfortable because you apparently dont know how to not touch the metal bits when unplugging something? Wait no, you're the one they write, "Dont eat package" for, aren't you?
> For example the absurdly large UK plugs with integral fuses date to first (or was it postwar? I forget) surge of electrification which,for expediency’s sake was often point-to-point (like “party line” phones) so local devices needed protection.
It was during WWII, and it was less expediency and more efficiency and saving on copper. Ring circuit can deliver more power to more surface with less copper.
The UK used to use standard radial topologies before WWII, this is also allowed by modern building code, and very high power devices (>3kW) generally have their own "radial" circuit.
This is outdated in some ways: South Africa formally adopted IEC 60906-1 (Type N) years ago as SANS 164-2 to replace its use of Type M (SANS 164-1). It was adopted as an optional local standard in 1992, the preferred standard in 2013, and mandatory for new installations in 2015.
IEC 60906-1 was developed to be the standardised global standard, with the intention of rolling it out across the EU first. However that didn't happen and so far South Africa is the only country that has chosen to adopt it.
Brazil and Switzerland have closely-related local forms of IEC 60906-1, but neither is fully compatible.
This article only scratches the surface. There are at least 241 NEMA (National Electrical Manufacturers Association) configurations in the USA. Each serves a purpose. Each voltage/amperage combo gets one in straight blade and locking. This prevents people from plugging into something dangerous. Also, there is support for obsolete stuff, such as two-wire.
I know it’s likely highly subjective and prone to local bias, but I feel a next step would be to do user testing of alternatives and derive a best form factor plug. What’s the best plug we could all be aspiring to. Some are clearly more usable than others.
One metric: easy of use in the dark/based on feel alone.
Safety seems like a big one too. Even the shoddiest fit should never have a visible powered part.
Reliability: Fit should be good. You should be easily able to plug a heavy transformer on a downward facing socket without it falling out by gravity alone.
Lastly, compactness. The standard should be compact so fittings can be good looking and not use too much space.
The UK grounded connector fails the last criteria. The US flat-face fails the first two.
Wonder if anyone ever arrived in the UK feeling the same way..
> (The requirement to have a fuse in every plug is a necessity for UK ring mains, but makes the things even bigger than they otherwise would be.)
Yes. It’s much too bulky to be acceptable anywhere where people aren’t used to that size (nor would anyone accept fuses in the plugs I think. Unsure about switches at sockets).
Why would people not accept fuses in plugs? (Apart from the size issue & in reality you could probably fit a fuse into a modern US plug without making it much bigger than it is now.)
Yup, because for those, the cable between the lights can’t take the current that the cable from the wall can deliver, so you ought to have a fuse for safety reasons - a short could cause a fire.
(Whether this is legally required in the US presumably depends on local electrical code.)
I definitely have a local bias but I believe this one has the best of all criteria. From compact to safety (improved 2007 version) and robustness as well as being polarized.
I don't like the Swiss plug. The 3x socket has a problem where a bulky charger will block all three sockets. I'd almost always rather have two sockets with some space between them.
And non-recessed sockets, which the Swiss socket allows while Schuko doesn't, make me uneasy.
The article seems to be mostly about voltages and plugs/sockets that the consumer will see at the outlets throughout their home.
It's interesting to look a little beyond that. Most of the places that offer 230 V at their outlets seem to be distributing power in the neighborhoods using a 3 phase 230 V system. Individual houses are wired to one phase of that.
In the US, distribution throughout a neighborhood is typically 15 kV. There is a 240 V center tapped step down transformer for each house. The normal outlets in the house are wired across half the transformer, giving 120 V. Ovens, water heaters, dryers, EV chargers, air conditioners, etc get wired across the full transformer giving 240 V.
There was an interesting comparison of the two approaches in this Quora answer that turned up in my Quora digest mailing two days ago [1]. (Not sure if the link will work without a Quora account).
> There is a 240 V center tapped step down transformer for each house.
Maybe in rural areas, but in (sub)urban areas, you'll have a... ?node? step-down transformer serving many homes.
> The normal outlets in the house are wired across half the transformer, giving 120 V
Would add that homes usually balance this, so half of 120V circuits will be wired to one phase, and half to the other. So sometimes you get power failures where half the house loses power. Also means installing power-line networking may only work (well) when they're on the same half of circuits of the house, unless you add a capacitor between the two sides to bridge the gap for high frequencies. Or turn on a 240V appliance to bridge the two sides together.
> Individual houses are wired to one phase of that.
In many countries houses get wired to all three phases and the phases get split up afterwards, sometimes with a few 3-phase plugs available for high-power applications.
It's also common in the US for neighborhoods to have 240V 3 phase, and for a neighborhood to have a common neutral. Each house gets the neutral and 2 of the hots. Hot to neutral gives 120V, hot to hot gives 208V. (240*sin(120 degrees))
The result is that the high voltage appliances need to support both 240V and 208V. Most appliances just design for 240V and test to ensure they don't break at 208V, and just give reduced power at 208V. Which is often fine, but a 208V stovetop is a pretty miserable experience.
You could run a heating element at full power on 208V by adding a center tap connected to neutral. For something fancy like an EV charger, you would probably need dual 120V AC/DC converters, which isn't worth the effort, given that constant-current loads run at 86% power (208/240), compared to resistive loads at 75% power (208/240 squared).
> The normal outlets in the house are wired across half the transformer, giving 120 V. Ovens, water heaters, dryers, EV chargers, air conditioners, etc get wired across the full transformer giving 240 V.
Why not just give the 120 V up and go full 240 V in every outlet?
> Why not just give the 120 V up and go full 240 V in every outlet?
No one feels it's worth the effort.
You'd need two sets of plugs in every home and redesign a whole bunch of appliances and sell both types during the change over period, which could last decades.
Italian sockets are a fun one. The plugs come in a 10A and 16A versions which are slightly different sizes. Newer sockets will usually take both plugs, but older sockets take one or the other.
The size looks very similar to European Schuko sockets, and if you jam it in, then it will just about fit (without an earth). You can get adapters all over the place, which is the way you are supposed to do it, but for older sockets they don't really hold very well so often come loose. Apparently there are sockets that will take all three, Schuko, 10A and 16A but I never saw those while living there.
It's not just to trick tourists though... When you buy electrical products, sometimes they come with an Italian plug, sometimes they come with a Schuko plug.
Meaning that nowadays three ways sockets ( Schucko/10 A/16 A) are common enough, but a Schuko (or a three way one) will take two "modules" whilst both the 10 A and the 16 A are narrower and take a single "module". (typically electric boxes in the wall are either a model 503 - three modules - or a 504 - four modules, but these latter oness can only be found in more recent houses), so until the use of 504's became more common, historicallty Schuko's were rare, as it was not possible to have in the same box a bipolar switch+fuse+Schuko (while it was possible to have bipolar switch+fuse+16A) which is/was the proper setup for high power sockets and with a single socket installed, it resulted in looking asymmetrical, see:
JFYI, recently came out a new kind of socket (not yet very common) that allows in two modules to insert either a Schuko or two 10 A (or 2x16 A or 1x10A and 1x16A):
As a tourist, Italian sockets always made me furious with those sideways grounding pads/pins. Any UK->EU adapter would be pushed out by those instantly. At one point, in a fit of rage, I ripped them out of the socket of a hostel I was staying at so I could use the socket (I wouldn't ever vandalise public property like that under any circumstances). I like to think that they wouldn't be missed.
The annoying thing about all these plugs is that you have to plug them into the socket the 'right' way around. Cylindrical plugs (phono, RCA, BNC, banana plugs, etc.) are much more convenient. Why can't all plugs be cylindrical?
76 comments
[ 4.2 ms ] story [ 138 ms ] threadSo when I had to make an emergency trip, I assumed my newish Dell with USB-C charging would be the same. And that assumption was false. Unless you're charging with 20V USB-C (not common outside of laptop chargers), it won't draw anything at all.
The M used in Israel might be different than the one pictured as it is used exclusively for 3 phase lines (so an AC that doesn't need 3 phase can then have a regular plug)
Type C (the "europlug") is a compatibility low-amperage plug (2.5A @ 250V) for shavers and small lamps and USB power adapters and such. It was designed to be compatible with the high-power Type C, E, F, and K popular in mainland europe, but providing a cheaper plug, and allowing for dedicated low-amperage circuits (e.g. shaver sockets which would be safer in bathrooms).
Type H (and N, which is brazilian) were then designed to be compatible with the Europlug in turn.
> Then, main room air conditioners use Type M - but at least that's standardized...except for when it isn't.
Possibly rather than Type M (which is a 15A plug) it's the 30A plug from the same over-arching BS546 standard? Or a similar-looking 3-phase plug? That's what I'd expect for high-power applications like AC. I assume the standard Type H is 15 or 16A single-phase aka the usual mains.
For example the absurdly large UK plugs with integral fuses date to first (or was it postwar? I forget) surge of electrification which,for expediency’s sake was often point-to-point (like “party line” phones) so local devices needed protection. Nobody else went this route (well, excepting some dodgy informal systems I’ve seen in India and southern Africa) so could get away with smaller, less expensive plugs.
(And as for terminology, why do we plug the plug into the plug in Australia?)
The modern US one (NEC) is probably the best trade off of size and safety (see my parallel comment on its physical design). Though I do think there is still too much use of two-prong plugs, despite the near ubiquity of grounded sockets these days.
You can’t see this structure in the standard diagrams such as the ones in the article but you can tell it for yourself by inspection.
Although it is extremely solidly built, it's mostly built for a different context: the UK mostly uses ring circuits (similar to a ring network) rather than the radial topology used pretty much everywhere else. This means there can't really be "small" fuses at the fusebox, you can't put a 16A fuse for the entire ring because that'd be the load for all the devices in the house.
As a result you need smaller fuses at the plug level. An advantage of that is that your fuses can then be sized specifically for the appliance cable, and thus you can safely use much smaller cable e.g. let's say that you want to design a 2.5A extension cable, you can put a 2.5A fuse in it and be safe. In a radial context where plugs are unfused, somebody could plug a 10A appliance on the 2.5A cable and melt the cable, the fuse only protects the "wall" circuit and won't blow until >16A (generally).
In fact this has been an issue in the US in the last few years: because of the low voltage, 20A circuits have become more common, but extension cords are still usually 16A. If you plug a 16A cord to a 20A circuit and draw 20A from it, the fuse will be perfectly happy (everything's fine as far as it's concerned) but the cord can catch on fire.
Anyway since they needed larger plugs for the fuse, I expect the UK standards body reinforced the plug while at it.
Technology Connections recently made a video about this.
https://www.youtube.com/watch?v=K_q-xnYRugQ
Like, it is possible, if one finger in a hand is touching the live prong, and another finger on the other hand is touching the neutral/ground prong, you'd pass current across your chest.
Or if you are touching something that is grounded, like a pipe/sink...
But actually dying this way is rather unlikely.
With respect to UK plugs, it's also common for them to have the live pins only half exposed, with the rest being insulator, to avoid the possibility of touching live pins while the plug is partially inserted.
On the mainland the sockets tend to be recessed to work around the risk, but the "europlugs" (which are not grounded) almost all have this property as they can't really be "sealed in".
Still harder to do than it looks, and to your point, very difficult to actually die from. Not impossible, but very unlikely.
34 years in the US. I have never been electrocuted when plugging/unplugging anything. I dont know anyone that has been.
Wtf are you playing at? Everywhere across the planet has to adopt things that make you comfortable because you apparently dont know how to not touch the metal bits when unplugging something? Wait no, you're the one they write, "Dont eat package" for, aren't you?
Why Argentina used the same plug as Australia I have no idea, and it's not fully documented as far as know.
It was during WWII, and it was less expediency and more efficiency and saving on copper. Ring circuit can deliver more power to more surface with less copper.
The UK used to use standard radial topologies before WWII, this is also allowed by modern building code, and very high power devices (>3kW) generally have their own "radial" circuit.
IEC 60906-1 was developed to be the standardised global standard, with the intention of rolling it out across the EU first. However that didn't happen and so far South Africa is the only country that has chosen to adopt it.
Brazil and Switzerland have closely-related local forms of IEC 60906-1, but neither is fully compatible.
One metric: easy of use in the dark/based on feel alone.
French sockets (https://www.worldstandards.eu/electricity/plugs-and-sockets/...) have a male pin that forces your plug one way only. This is terrible because most (if not all) of such plugs are bent and sometimes do not physically fit.
German ones (https://www.worldstandards.eu/electricity/plugs-and-sockets/...) do not have a prong and ple plugs can be rotated 180°
This is extremely uncommon and basically only happens with power strips which both are the "wrong" way around and can't be reversed.
(and since pretty much every plug nowadays is an E/F hybrid, you can easily get a type F power strip for the rare case where it's needed).
Beside the case of the strip you mention, there is also the more mundane physical space above the ground, or other physical limitations.
In my case it is not extremely uncommon since I thought to myself a few times recently "oh no, again this £¨%¨¨£ pin".
Reliability: Fit should be good. You should be easily able to plug a heavy transformer on a downward facing socket without it falling out by gravity alone.
Lastly, compactness. The standard should be compact so fittings can be good looking and not use too much space.
The UK grounded connector fails the last criteria. The US flat-face fails the first two.
(The requirement to have a fuse in every plug is a necessity for UK ring mains, but makes the things even bigger than they otherwise would be.)
Wonder if anyone ever arrived in the UK feeling the same way..
> (The requirement to have a fuse in every plug is a necessity for UK ring mains, but makes the things even bigger than they otherwise would be.)
Yes. It’s much too bulky to be acceptable anywhere where people aren’t used to that size (nor would anyone accept fuses in the plugs I think. Unsure about switches at sockets).
(Whether this is legally required in the US presumably depends on local electrical code.)
Swiss Plug:
https://www.worldstandards.eu/electricity/plugs-and-sockets/...
https://en.m.wikipedia.org/wiki/SN_441011
Compact 3 socket version: https://www.bauhaus.ch/product-images/52/95/22025295/1009627...
Multiphase: https://en.m.wikipedia.org/wiki/SN_441011#/media/File:SEV_10...
Chart of all current/phase versions: http://www.toplight.ch/info/ch_plugs.pdf
Indeed much more compact than type E or F.
And non-recessed sockets, which the Swiss socket allows while Schuko doesn't, make me uneasy.
[1] https://en.m.wikipedia.org/wiki/SN_441011#Structure_of_the_S...
It's interesting to look a little beyond that. Most of the places that offer 230 V at their outlets seem to be distributing power in the neighborhoods using a 3 phase 230 V system. Individual houses are wired to one phase of that.
In the US, distribution throughout a neighborhood is typically 15 kV. There is a 240 V center tapped step down transformer for each house. The normal outlets in the house are wired across half the transformer, giving 120 V. Ovens, water heaters, dryers, EV chargers, air conditioners, etc get wired across the full transformer giving 240 V.
There was an interesting comparison of the two approaches in this Quora answer that turned up in my Quora digest mailing two days ago [1]. (Not sure if the link will work without a Quora account).
[1] https://qr.ae/pGosj7
Or all 3. I thought this was most common. 3x20A (or 16 or 25) 240V is the standard for detached houses in parts of Northern Europe at least.
Maybe in rural areas, but in (sub)urban areas, you'll have a... ?node? step-down transformer serving many homes.
> The normal outlets in the house are wired across half the transformer, giving 120 V
Would add that homes usually balance this, so half of 120V circuits will be wired to one phase, and half to the other. So sometimes you get power failures where half the house loses power. Also means installing power-line networking may only work (well) when they're on the same half of circuits of the house, unless you add a capacitor between the two sides to bridge the gap for high frequencies. Or turn on a 240V appliance to bridge the two sides together.
In many countries houses get wired to all three phases and the phases get split up afterwards, sometimes with a few 3-phase plugs available for high-power applications.
The result is that the high voltage appliances need to support both 240V and 208V. Most appliances just design for 240V and test to ensure they don't break at 208V, and just give reduced power at 208V. Which is often fine, but a 208V stovetop is a pretty miserable experience.
Why not just give the 120 V up and go full 240 V in every outlet?
No one feels it's worth the effort.
You'd need two sets of plugs in every home and redesign a whole bunch of appliances and sell both types during the change over period, which could last decades.
Fixed that for you.
The size looks very similar to European Schuko sockets, and if you jam it in, then it will just about fit (without an earth). You can get adapters all over the place, which is the way you are supposed to do it, but for older sockets they don't really hold very well so often come loose. Apparently there are sockets that will take all three, Schuko, 10A and 16A but I never saw those while living there.
It's not just to trick tourists though... When you buy electrical products, sometimes they come with an Italian plug, sometimes they come with a Schuko plug.
Meaning that nowadays three ways sockets ( Schucko/10 A/16 A) are common enough, but a Schuko (or a three way one) will take two "modules" whilst both the 10 A and the 16 A are narrower and take a single "module". (typically electric boxes in the wall are either a model 503 - three modules - or a 504 - four modules, but these latter oness can only be found in more recent houses), so until the use of 504's became more common, historicallty Schuko's were rare, as it was not possible to have in the same box a bipolar switch+fuse+Schuko (while it was possible to have bipolar switch+fuse+16A) which is/was the proper setup for high power sockets and with a single socket installed, it resulted in looking asymmetrical, see:
https://www.elettronew.com/blog/2017/05/11/presa-elettrica-t...
JFYI, recently came out a new kind of socket (not yet very common) that allows in two modules to insert either a Schuko or two 10 A (or 2x16 A or 1x10A and 1x16A):
https://www.archiproducts.com/newsletter/dossier/193843
The 10A one is actually compatible with the class 2 (earthless) Europlugs:
https://en.wikipedia.org/wiki/Europlug
Schuko's have larger pins, and it is not a good idea to jam them in a normal Italian 10A plug as the plastic cover of the plug might crack.
Isn't one particular plug prevalent in all modern installations or at least prevalent in particular geographical areas?