Nice overview of the 240v US electrical system

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A few things from an Irish perspective

1. Switches on sockets. They’re used here too, but not universally. They’re not that big on the socket plate and not particularly unsightly. They basically just save you from having to plug things out to isolate them. Like I can reach down and switch off a big mess of power strips with two small switches on the wall. They’re definitely not essential, but they are convenient. They’re also not at all required by the regulations here and are purely optional.

Whether you want them or is up to you. I’d agree though. They’re a mild convenience and that’s about all. You certainly live without them, but they’re kind of useful in some ways.

The shutters on sockets being universal is definitely a safety advantage though and makes them child proof by default.

2. Size of U.K. / Irish plugs. The newer designs of moulded plugs aren’t that big, certainly compared to Schuko and most phone chargers now come with a folding (usually plastic) “ground” pin (a ground pin is required to open the socket outlet). The unfortunate bit is that for low powered, non grounded appliances, there is no such thing as a two pin plug, so everything has a plug that’s at least as bulky as 16 amp Schuko, which is a bit ludicrous.

They never really foresaw the need for plugs for very portable appliances. The standard originated in the 1940s and replaced an even bulkier system. So it’s not likely they really ever contemplated a world of electronic devices and people carrying things like laptops. They’ve definitely been slimmed down though. If you look at the plug on say an Apple mains cable, they’re about as neat as you can go with that plug design.

3. 50Hz vs 60Hz. There’s no particular logic or signifiant advantage to either. AEG and a bunch of other companies just settled on 50Hz back at the dawn of AC power. We standardised on 220V 50Hz here in Ireland before 1923. So it’s been around a long time. (The standard CENELEC and EU spec moved to 230V, to accommodate the UK which had standardised on 240V 50Hz. That has now extended to IEC recommendations, so the few others who used 240V, like Australia and NZ are included.)

4. U.K. / Ireland plugs may be enormous but the sockets are a lot neater than continental European designs that have deep recesses - Schuko/French sockets are pretty ugly looking in my opinion and even get full of dust and gunk due to the deep recess. Some French designs now incorporate a plate that covers the recess and is pushed back when the plug is inserted, giving you a flush socket when no plug is inserted, which looks far better but they’re complicated and very expensive relative to standard French sockets.

5, US plugs genuinely do lack finger protection. It’s the only place I’ve ever been accidentally shocked. I reached behind a desk and touched live pins of a partially sticking out plug. That’s impossible with modern UK, or recessed Schuko / French designs. I think there’s some risk of it in Switzerland and Italy, but only with obsolete fittings. There’s also a slight risk of it with older U.K. plugs that lacked sheathed pins but they’re fairly rare at this stage.

On the other side of it, despite their small size, NEMA plugs make a firm connection. The blades are designed to make pretty secure and solid contact.

If they added sheathed pins it would make them a very decent standard. Australia’s plugs are basically a derivative of a NEMA type with slanted pins. They’ve evolved a few extra safety features like sheathed pins, which seem to be quite a feasible addition to the NEMA 6-15 And 6-20 plugs in use.

I’d argue that US 240V plugs and sockets should probably be recessed like Schuko. There’s a fairly significant risk of shock on some of the dryer plug / stove plug designs.
 
Weird sh*t from a country that changed to metric...

A couple of funnies about going metric...

1. "clocks and calendars aren't metric but nobody has a problem with those..." Measurement of time pre-dates metric and is based in hard facts like how long it takes for the Earth to complete a lap of the Sun and how long elapses between one sunrise and the next sunrise... However a few years after Australia went metric, a TV news program did an April Fools Day news broadcast announcing that Australia was going to adopt "Metric Time" with 100 seconds to a minute and 100 minutes to an hour." (now that's fake news...)

2. Australia went metric back in 1974 but to save the building industry from having to change all its products, they used "metric-ised" terms for the existing imperial measurements - so 2 inch by 4 inch pine framing (which we call 4x2, not 2x4) was renamed 100x50 pine framing. (100mm = 4 inches.) And lengths are still in foot increments, now called 0.3 metre lengths. All these years later, the imperial terms are still used, and imperial and metric are often mixed in one sentence - "can I have 2.1 metres of 4x2 pine?" is quite normal. Plumbing is the same - you buy half inch copper pipe in six metre lengths.

3. "SI system doesn't vary but tolerances and specs do." Yes but that doesn't change for imperial vs metric. One of my favourite cars ever, the (unique to Australia) Leyland P76 of 1973 was designed by Leyland Australia to suit Australian conditions, but they were a subsidiary of British Leyland and every decision had to be signed off by head office in the UK. Leyland Australia intended to contract Karmann in Germany to manufacture the sheetmetal presses for stamping body panels, but BL in the UK insisted that their own subsidiary, Pressed Metal Corporation in the UK, got the job. PMC ignored the blueprints from Australia that specified 3/16th inch gaps between panels, and without informing the Australian subsidiary, made the presses to create panels with 5/16th inch gaps. (as was their sloppy practise in the UK.) The door seals and hinges were made locally in Australia and were designed to suit the 3/16 gaps. The cars that were manufactured had all sorts of problems such as water and dust leaks, ill-fitting panels, and hard-to-shut doors. The parent company refused to fund the press dies being remanufactured to the correct specification, so the assemblers had to create bodge solutions like fitting shims behind the hinges to align the doors better, and having new, thicker softer door seals to take up the excessive gaps. This was just bad management, not a metric or imperial issue, but I thought you might like the story.
 
"The SI System Doesn't Vary but Tolerances and Specs

Not sure what you mean.

The SI is a system of measurement units, and has nothing to do with standard or tolerances. https://www.bipm.org/en/about-us/

The ISO standards are, well, standards, and they state both the size and the tolerance to ensure compatibility worldwide. https://www.iso.org/home.html

Care to explain?
 
Look, I'm just going by what my machining instructor told us: Metric is great for calcs and international stuff, but its implementation varies from nation to nation and from continent to continent. That was about 15 years ago. Maybe it's improved since then. I would guess it's a problem with stuff like fasteners, where a bolt made in one country may or may not have a nut fit the same if the nut was made elsewhere.

 

I'd have to go back to the college and ask him for more details, or go search the internet for more info. All I can say now is that  what I was taught is that the metric system looks great in concept but in implementation it is not absolutely the uniform standard across national boundaries that it's supposed to be.
 
OK, here's an interesting discussion of Metric vs. "US Customary" systems, from Quora:

 

<span id="__w2_wEe5l32t47_link" class="photo_tooltip u-inline"><span class="ui_avatar u-flex-inline ui_avatar--large u-flex-none"> </span></span>

<span id="wEe5l32t30"><span id="wEe5l32t39"><span id="__w2_wEe5l32t40_link">Craig Weiler</span></span><span id="__w2_wEe5l32t31_cred_text" class="NameCredential">, Master Opinionator</span></span>

<span id="wEe5l32t41">Answered Jan 29, 2019</span><span class="bullet"> · </span>Author has <span class="bold_num">3.4k</span> answers and <span class="bold_num">20m</span> answer views

The metric system was not developed organically, nor did the creators let the organic system (Imperial) dictate what was needed. As a result, there are some flaws in the metric system.

The biggest flaw is that metric is base 10 instead of base 12.

10 is divisible by 2 and 5.

12 is divisible by 2,3,4 and 6, making a far superior choice for measuring.

With base 10 you basically remove the ability to work with fractions, which are better for mental field work. Base 12 is infinitely divisible: 1/2, 1/4, 1/8, 1/16, 1/32 and so on. You cannot do this in metric. Instead you run into un-intuitive strings of numbers. .5, .25, .125, .0625, .03125.

Why would this be important? It also gives you a set of ready made tolerances that are easy to follow and scale up and down quite easily. This is certainly doable in metric, it just takes a little more work.

Metric lacks two measurements that are quite useful: The inch and the foot. These have been replaced by the useless decimeter, an artifact of the base 10 system.

The foot and the inch were created because they were needed and they seamlessly fit into the yard, because it’s all base 12.

When it comes to volume measurements, base 12 is perhaps not so important, but what is important is to have a large variety of sizes to work with so that measuring is fast and easy.

For cooking Imperial offers teaspoon, tablespoon, ounce, cup, pint, quart and gallon. Metric offers liters and divisions of liters.

The Imperial system wasn’t designed to be easy to understand, it was designed to be efficient. And it is. If you check this cooking chart you’ll notice that with Imperial whatever measurement you’re using, you’ll be in single digits. 3 of this, 4 of that. It might be a bit cumbersome for a newcomer, but it’s easy to work fast and because the words don’t sound like each other it’s easier to avoid mistakes. There is very little actual measuring because there are so many sizes to choose from. If your eyes aren’t very good (Imperial was developed before eyeglasses were common.) you can make mistakes easier in metric.

Obviously most of the world does just fine with metric and it certainly isn’t a bad system by any means, but it has traded simplicity for usefulness in some situations.

https://www.quora.com/What-are-some...e-metric-system-international-system-of-units
 
More on the cons of the metric system (bear in mind I have a university chemistry degree so I am quite used to metric measurements. But like any system it does have its pros and cons):

 

<h3>The Cons of Metric System</h3>
1. The metric system seems logical and practical but in reality it doesn’t emerge as helpful. Rarely does one use any scale of measurement at home or even at office. Stores and manufacturers can always use scales to measure but when you have to cook or weigh something, it is not always easy to know how much is what you need. If you are slicing onions at home or making dough, how do you know how many onions you must take or how much flour you should use based on the metric system. One cannot measure 200 grams without a scale. This is a problem with other units as well, as opposed to how human scale measurements had originated such as with cup, foot or thumb.

2. The metric system is quite vast. It is a little too wide ranged for efficient use in reality. The metric system works fine when you are working on math or science in theory or on paper. It doesn’t really help that a base unit is gram and its subsequent higher unit is kilogram which is a thousand times in value. There is 1 gram which is essentially a bit of salt on your finger tip and then you have 1 kilogram which is the weight of a whole spring chicken. There is no unit in the interim. This creates a vast range. Although manufacturers and scales have made it simpler, yet there is a lot that can fall into this range and be quite perplexing.

3. The metric system has some rather quaint names or prefixes. Liters and meters are not problems but deca, deci, milli and centi are some work for the tongue. Imagine pronouncing milliliter, millimeter, centimeter, deciliter, decameter and centiliter. For those who have grown up studying the metric system and its prefixes may have gotten accustomed by now but those who have no exposure will struggle, at least initially.

4. The metric system is also criticized for being too scientific and arbitrary as a result in the real world. Consider what meter is: it is the distance traveled by light in vacuum in a time of 1⁄299,792,458 of a second. This may not be relevant for those only looking at packaging or measurements but when you need to delve deeper these complexities will come to the fore. The arbitrariness is stark when you consider time. 1 second is the base unit, 1 minute is 60 seconds, 1 decasecond is 100 seconds so it is 1 minute and 40 seconds, kilosecond is 10,000 seconds but it is not a 1,000 minutes, instead it is 2 hours 46 minutes and 40 seconds.

https://greengarageblog.org/7-pros-and-cons-of-metric-system
 
Why the Metric System Might Be Screwed

A bit sensational, but an interesting article about the difficulty of maintaining the central standard of the metric system: the reference kilogram weight stored in Paris:

 

Hidden in a vault outside Paris, vacuum-sealed under three bell jars, sits a palm-sized metal cylinder known as the International Prototype Kilogram, or “Le Grand K.” Forged in 1879 from an alloy of platinum and iridium, it was hailed as the “perfect” kilogram—the gold standard by which other kilograms would be judged.

 

Although it’s arguably the world’s most famous weight, Le Grand K doesn’t get out much. Since hydrocarbons on fingertips or moisture in the air could contaminate its pristine surface, it goes untouched for decades, under triple lock and key at the International Bureau of Weights and Measures. Every 40 years, however, it makes an appearance. The weight is ushered from its chamber, washed with alcohol, polished, and weighed against 80 official replicas hand-delivered from laboratories around the world. Today, whenever scientists need to verify something is precisely one kilogram, they turn to one of these replicas, over which Le Grand K reigns supreme....

 

While basing measurements on tangible benchmarks was an improvement, using physical standards wasn’t without its flaws. For one, they have a nasty habit of changing. In Le Grand K’s case, it’s been losing weight. At its most recent weigh-in in 1988, it was found to be 0.05 milligrams—about the weight of a grain of sand—lighter than its underling replicas. Experts aren’t sure where this weight went, but some theorize that the replicas have been handled more often, which could subtly add weight. Others postulate Le Grand K’s alloy is “outgassing,” which means air is gradually escaping the metal.

 

Whatever the reason for Le Grand K’s gradual wasting away, it’s got scientists scrambling for a more reliable standard. Some argue that this is long overdue, since all other units of measurement are already defined by fundamental constants of nature that can be reproduced anywhere anytime (provided you’ve got some sophisticated lab equipment). The meter, for example, used to be defined by a metal rod stored alongside Le Grand K. But in 1983, it was redefined as the distance light travels in a vacuum during 1/299,792,458 of a second.

 

Standardizing the kilogram has been trickier, though. Australian scientists are polishing a one-kilogram sphere of silicon, hoping that they’ll be able to count the number of atoms it contains to create a more accurate standard. American physicists at the National Institute of Standards and Technology (NIST) are attempting to redefine a kilogram in terms of the amount of voltage required to levitate a weight. But so far, neither approach can match Le Grand K’s accuracy.

 

Why should we care whether a kilogram in a vault is “perfect” or not? Because it’s bad news when your standard is no longer standardized. While no one’s worried whether a single kilogram of apples is a hair lighter or heavier at the produce stand, a small discrepancy can become a gargantuan one if you’re dealing with, say, a whole tanker of wheat. The kilogram is also used as a building block in other measurements. The joule, for instance, is the amount of energy required to move a one-kilogram weight one meter. The candela, a measure of the brightness of light, is measured in joules per second.

 

These links mean that if the kilogram is flawed, so are the joule and candela, which could eventually cause problems in an array of industries, particularly in technology. As microchips process more information at higher speeds, even tiny deviations will lead to catastrophes. Le Grand K’s unreliability “will start to be noticeable in the next decade or two in the electronics industry,” warns NIST physicist Richard Steiner. If your next smartphone is buggy, you’ll know which hunk of metal to blame.

 

https://www.mentalfloss.com/article...logram-and-why-metric-system-might-be-screwed
 
Well, quite a lot of debate about it, but they forget one thing. The imperial standards are defined by units of the metric system. Besides that, there are a lot of differences between the Imperial standard in the USA and the British standard, which makes those measurements confusing when you are exchanging measures in an international setting.

http://www.legislation.gov.uk/ukpga/1985/72
 
"Rarely does one use any scale of measurement"

Well most European households have a scale. Just like most north American households have cups and spoons. When people see my cups and spoons they often ask what they are. Weighing ingredients is way more precise anyway, a lot of serious bakers on the north American continent purchase a scale for serious baking. Try and weigh a cup of flour several times and every time the outcome will be different.
 
Maybe the grapes are sour?

With the due respect, these seems to me very uninformed opinions (to put it extremely politely) showing an attitude of the sort “I don't know your system, but I am sure that mine is better”.

A few examples:

1) “One cannot measure 200 grams without a scale”
And don't you need some sort of tool to measure “one cup”? Does it make any difference having to buy a scale or a set of measuring cups?

2) “a base unit is gram and its subsequent higher unit is kilogram which is a thousand times in value”
Absolutely wrong. The SI is based on 10, hence there is always a unit which is ten times bigger and another that is ten time smaller: you have the decagram (not much used) and the hectogram; for instance, in Italy sliced ham (Parma ham, just for clarity) and cheese are typically sold by the hectogram while instead fruits and meat are sold by the kilogram (“I need one hecto[gram] of ham and half a kilo[gram] of minced beef”).
And in case you wonder, you also have the decigram (1/10 of a gram) and the centigram (1/100 of a gram) and the milligram (1/1000 of a gram) and many, many other, from the yottagram, which is 10^24 grams (write 1 and then add 24 zeroes) to the yoctogram, which is 1/10^24 of gram.

3) “For those who have grown up studying the metric system and its prefixes may have gotten accustomed by now but those who have no exposure will struggle, at least initially.”
The fact that someone does not know how to use the SI does not mean there is something wrong with the SI. It is also interesting that the same applies to anything, from cooking to differential equations: until you have learned, it is difficult.

4) “Consider what meter is: it is the distance traveled by light in vacuum in a time of 1⁄299,792,458 of a second”
Because all the US customary system units are defined in metric units (one inch is defined as 25.4 mm and one yard is defined as 0.9144 m and so on) the objection does not make any sense other that showing that who wrote that sentence is not qualified to discuss the matter.

And finally:

“Why the metric system might be screwed”
The problem with the kilogram sample is known since years:
“However, due to the inevitable accumulation of contaminants on surfaces, the international prototype is subject to reversible surface contamination that approaches 1 μg per year in mass. For this reason, the CIPM [Comité international des poids et mesures] declared that, pending further research, the reference mass of the international prototype is that immediately after cleaning and washing by a specified method”. (from “Le Système international d’unités” 8e édition 2006, Organisation intergouvernementale de la Convention du Mètre)

“These links mean that if the kilogram is flawed, so are the joule and candela”
And because of point 4) above, also the inch, and the yard, and the pound… If the SI is screwed, the US customary system follows immediately.

But then I also wonder: haven't we seen the same sort of obscurantism before? And am I the only one who smells a certain “sour grapes” attitude?
 
Speaking of easy to calculate around, 1/299,792,458 of a second?

 

Still more convenient than π.  Dam Egyptians.


 

Which brings us back to 50Hz, a base-10 number vs 60, a base-12 number, more readily divisible.  Was it like NTSC/PAL, where the euros didn't want to pay US royalties?  Can you patent Hertz?  Or PAL/SECAM where France didn't want to pay German royalties and made a system that can only be edited every 8th frame.

 

I use metric on my car because that's what it is.  Metric when I'm formulating because that's what labware and molecules are calibrated in.  Metric to microwave maple syrup, because I'm using the "cup" to boil coffeewater.  US imperial for everything else.  And let that be an end to it.  END TO IT.  [Ringo, HELP!]
 
Almost everything about the metric system mention above is more about familiarity, or lack there of, in the USA.

Measuring with an electronic scale is so much more convenient. I can place a bowl on a scale, zero the scale and measure any additional ingredients, including water based liquid without any complications or needing to get scoops or jugs.

My food processor has a built in scales, so all I have to do is hit zero and I can add any extra ingredients very easily.

Inches and feet? Don’t really see what the advantage is? You tend to just think in centimetres: I intuitively know what 1, 5, 10, 50, 100 cm looks like without having to measure anything. A typical door here is exactly 2 meters, I’m about 193cm. Everything else is worked from that.

I know what a kg feels like - it’s a litre of milk. So my intuitive reference is that. Same with smaller amounts like a half kg is a bag of sugar. I would know roughly what 100g, 250g etc feel like without weighing anything.

Then things like temperature - it’s what you’re used to. I’ve no intuitive feel for °F but I could probably tell you it was 23°C and not 25°C today or that a hot shower is just under 40°C.

We are also probably more used to using technical units than Americans (in the USA anyway). You’ll always set washing machines, dishwashers and so on by numerical temp references. Not just warm, hot, cold. Also things like showers incredibly have temperatures set numerically on the dial / knob. So you just become familiar with them.

As for the reference to standards of things being different in different countries. That’s a failure of harmonisation and standardisation. It’s absolutely nothing to do with SI.
Industry standards are set by national bodies or industry bodies and things evolve to a particular set of norms.

That’s precisely why the be EU and European standards bodies spent so much time and effort on harmonisation of standards in Europe since the 1950s. It’s what has made the single market function. Otherwise you would have endless variations of devices and standards that were slightly incompatible with others.

As for PAL, SECAM and NTSC (all dead standards now) - their origins were driven by technical and commercial factors. Colour systems had to be overlaid on previous monochrome systems, which had different signal characteristics, differing numbers of lines, bandwidth, channel spacing, audio subcarriers and so on due to where and when they originated.

NTSC colour also launched quite a bit earlier. European research having been seriously delayed by the economic fallout of WWII.

By the time European TV companies and vendors of broadcast equipment began to look at colour switchover, they also had an opportunity to improve on NTSC, which had flaws, particularly with maintaining hue accuracy. PAL essentially fixed colour accuracy using error checking / cancellation using phase alternating lines, which was a technical solution developed in Germany before WWII.

SECAM’s delay line (memory), or at least something somewhat inspired by it, got incorporated into more advanced PAL decoders later on, which improved PAL colour accuracy further.

Early Sony PAL TVs wouldn’t pay the licence to Telefunken for the PAL technology, so essentially converted PAL to 625 line NTSC internally for the first few years of Sony colour TVs in Europe:

As for the frame rate / field rate - it’s linked to the mains frequency. This is both because it was a handy reference and also because TV cameras and screens had to strobe in compatibility wiring mains powered lighting to avoid visual effects.

Later PAL TVs increased the refresh rate to 100Hz + using digital processing to increase the frame rate.

Then you also had extensions to PAL using digital components to provide PALplus, a widescreen format that lasted until the introduction of digital tv and NICAM stereo, which used a protocol that resembles ISDN somewhat to carry CD quality digital stereo or two language tracks in mono. There was also a competing German Zweikanalton (A2) analogue stereo system which was basically just an FM stereo subcarrier. NICAM was also used with SECAM in France.

Btw SECAM was really never used in production. French TV stations typically shot and produced using PAL and then broadcast in SECAM. Although, studio editing. It was less than ideal for video editing and mixing, which was a major reason it never really extended beyond broadcast. As a broadcast standard SECAM performed quite nicely. It was very colour accurate, but tended to behave differently to PAL in a bad signal. PAL would tend to drop colour. SECAM could sometimes drop one or two colours and you’d get a “SECAM fire” where it could start missing one or more of R G or B. Bear in mind SECAM transmitted the colour information sequentially, using delay lines, PAL and NTSC both combined them. So, if you screw up signals on SECAM you can get colour tv with odd colours, the other two will tend to go into monochrome.

That being said, you don’t typically edit and mix using composite signals anyway: it was usually done with component video, RGB and audio kept separate and then you broadcast in composite like NTSC, PAL or SECAM.

Serious drama production was still shot to film well into the 1980s and 90s until serious digital formats arrived. If you look at say Star Trek TNG, that was all shot to film. Cheaper productions were shot to analogue tape - sitcoms and so on. Analogue, electronic editing and vision mixing tended to remain fairly unsophisticated in TV until non linear, digital production anyway.

Overall, watching PAL or SECAM looked exactly the same and both had higher resolution and colour accuracy than NTSC, but a lower frame rate - which isn’t actually noticeable tbh. A lot of what you’ll see online is people shooting a PAL screen with a camera that sees a strobe because it’s scanning at 30 FPS instead of 25. In reality, PAL or SECAM screens didn’t flicker and later TVs double or even more than double the refresh rate.

France actually had 819 line HD television as it’s monochrome standard after WWII. It looked fantastic but they moved to standard 625 line based systems for practical reasons when colour was introduced. The bandwidth of 819 line SECAM was just too high.
The other addition to European TV was Teletext, a digital information system carried on a hidden line. It basically carried several hundred pages of text and special chars which could be used to build basic graphics. You’d 900 or so numbered pages and you jumped around using either page numbers or 4 colour coded hot link buttons on the remote.

Teletext was developed initially by Philips Electronics’ CAL laboratories and pitched to U.K. tv stations in the early 70s and from there evolved into a EBU adopted standard. There was, of course, a competing French system, which used similar technology to Minitel, but subsequently fell away to the EBU standards.

Teletext lasted from the early 1970s until the end of analogue TV and has modern replacements in digital tv systems.

It was a very successful service and probably one of the first mass market digital platforms for news and information, entertainment etc.

Each TV channel carried its own teletext service, some were very comprehensive magazines. Others were just TV guides and silly stuff, but they were often used to provide extra information to go along side shows - recipes, competitions, sports results etc etc

Page 888 was usually used to do live subtitling / closed captioning. So you just hit text and 888 and that’s how you watched with subtitles on analogue tv.

European TV systems tend to be developed by commercial companies but with the view to creating open standards that are harmonised by the EBU (European Broadcasting Union), famous for the Eurovision.

The current batch of EBU broadcasting standards are known as DVB (Digital Video Broadcasting) which comes in a variety of variants DVB-T (terrestrial) DVB-S (satellite), DVB-C (cable) etc. They evolve and maintain a concept of backwards compatibility and also extensibility. The fact they’re an open set or standards, a bit like the way the GSM family of standards works in the mobile phone world, they have tended to become global standards. So DVB is by far and away the most widespread tv transmission system in the world.

[this post was last edited: 6/28/2020-09:29]
 
arguments against metric

When the arguments used against Metric are so illogical, clumsy and factually wrong, that tends to support metric....

Cup measure is a metric measure: 1 metric cup is 250 ml, or a quarter of a litre. I have a set of metric cup measures in 1/4, 1/3, 1/2, 2/3, 3/4 and 1 cup scoops. I also have a set of Sunbeam digital scales and use that when bread making but generally use cup measures otherwise.

Spoon measures vary around the world but are certainly used in cooking in both metric and imperial countries. In Australia, teaspoon = 5 ml, dessert spoon = 10 ml and tablespoon = 20 ml. But to us, a dessert spoon is the biggest for eating, a tablespoon is for serving. I think US tablespoon is 15 ml, maybe our mouths are smaller? ;)

The metre was calculated by dividing the distance from the North pole to the equator by ten million. The later light-related definition came about because the original calculations to work out the one-ten-millionth measure were fractionally wrong, so a metre in use wasn't exactly a metre by definition. So a new definition was created to match the metre in use. The original definition was created in the 1700s so you can understand the maths being a bit out. see the link...

"The foot and the inch were created because they were needed and they seamlessly fit into the yard, because it’s all base 12." ... Yeah but it isn't all base 12. 12 inches in a foot, but only 3 feet in a yard. 1760 yards in a mile. 16 ounces in a pound. 14 pounds in a stone. Good grief, imperial measures require you to keep so much trivia in your head.

"you can make mistakes easier in metric." Why? How? There is no inherent reason why. It's just a matter of what you are used to. If you grow up with one system, the other will be a bit difficult for a while. I am fluent in both, and find metric much easier in cooking and in building. In particular, I find measuring accurate cuts in woodwork much easier to comprehend in millimetres than feet+inches+fractions of an inch.

I remember when I was in the USA in Illinois in 1981/2 and the US was toying with metric back then. There was a road sign on a main road somewhere around Lockport or Joliet that said something like "Metric test site. Speed limits will be displayed in KM/H for the next 50 miles." So mix metric and imperial on one sign?? I remember thinking "Just make the change and get over it."

 
Reply #34

I, apparently, was not clear.

 

My reference was not to SI units. I was referring to variations in how much deviation from a given dimension is permitted by various manufacturers.

 

Indeed, I was trying to express exactly what you said about SI units.

 

It's not the 'fault' of the SI units that some places in the world have bad manufacturing practices.

 

 
 
Teletext

Page 888 still works on the BBC. I use it now and then when someone is hard to understand. The BBC doesn't support the rest of the system anymore. The Dutch public channels still have Teletekst, the latest news is always fresh from the press. Germany has Videotext on ARD, ZDF, NDR, RTL, Sat.1 and perhaps others.

Teletext has been a great source for the latest Covid-19 news.
 
Hi James

that stuff about TV standards was fascinating. I had read about PAL vs NTSC vs SECAM years ago and the article was disparaging about SECAM, they gave a joke acronym for SECAM which I don't remember, I don't speak French but it basically translated as "at least it isn't American."

We paid a small fortune for a Teletext TV when they first came out in Australia. It was a 30 cm / 12 inch Telefunken. It gave us sharemarket prices that were only an hour or so old, a huge advance! Also weather reports. There was a lot of horse racing data on teletext here, but of no interest to me. Teletext was only on one TV network here, channel 7. So primitive from today's perspective but we were very impressed. Our Telefunken was spectacularly unreliable, too. Always off for repair. It was made in Singapore, not sure if it was really a Telefunken product or a piece of generic junk with a Telefunken badge for the Australian market.

teletext has disappeared from Australia now, except that the TAB betting agency uses it for in store horse racing results displays.
 
The emotional heat over these topics fascinates me

Goodness!

 

Anyone who has dealt with both systems knows that the Metric is easy as pie and far better for scaling up and down.

 

As to PAL/SECAM vs. NTSC, let's not forget that NTSC was designed to be backwards compatible to the outrageously expensive and (then) only a few years old TV sets already owned by millions in the US.

 

One big reason PAL/SECAM work better is because they weren't saddled with that demand.

 

Then again, it's awfully easy to be critical when one, oneself, hasn't contributed anything.
 
Hi Panthera

I hope I haven't put in too much "emotional heat." Nice term.

As a kid I just "got" the metric system as soon as it was introduced here. It just clicked in my little brain. I used to collect matchbox covers at the time and Redheads matches even did a series of "Think Metric" matchbox labels. The theme was to try not to think in imperial and then convert, but to try to think in metric.
There is something about the logic of metric that I have always appreciated, perhaps partly because I have never been any good at fractions.

I can't help myself, I have to stick up for metric. It's hard wired in me. ;)
 
Chris,

I feel the same way - I left the US whilst still too young to really understand that 'Metric' was supposed to be hard and ridiculous.

So, learning to use it in Germany was super simple.

 

I still use Metric whenever possible now that I'm back in the US.
 
Never The Same Colour Twice

Yup. Until about '67 that was really true. After that, things got properly synced and the problem improved, a lot.

By the end, I'd say NTSC was every bit as good as PAL at colour rendition.
 
Backwards compatible NTSC?

NTSC was backwards compatible with some previous colour system? Or, you mean black & white / monochrome tv?

PAL and SECAM, like NTSC are colour overlays. They’re sat on top of older monochrome systems. In Ireland and the U.K. for example the underlying monochrome systems was known as System I. That’s why the colour system is PAL I

All of those colour systems are backwards compatible with previous B&W systems. So if you tuned a colour tv into a B&W signal, it saw B&W and worked perfectly and the existing fleet of B&W TVs could watch colour signals in black and white.

There were still B&W broadcasts of some programmes as late as the 1970s and black and white television sets were absolutely still around, even in the 1980s you still had portable TVs that weren’t colour.

At one stage you used to be able to pay for a Black & White or Colour TV licence (the fee that funds public service tv)

A weak PAL signal would drop to B&W.

Weak SECAM signals could go weirder as the colour components would intermittently, and seperatelu drop out or become snowy. So you could get coloured snow or dropout of one or more of the prime colours. The underlying monochrome (luminance) signal was often still decodable but the colour overlay could be screwy. Later SECAM TVs would just cut the colour. Older ones would display a “SECAM fire”
 
NTSC = Never The Same Color (twice).
PAL = People Are Lavender
SÉCAM = le Système Essentiellement au Contraire à l'Ameican Method!

To be to fair, all three were extremely successful and long lived standards and delivered very watchable TV to billions of people for over half a century.

I've worked in the sector and remember the last days of analogue. We sometimes had feeds from multiple countries. You could identify PAL vs NTSC just looking at a monitor. Slightly better resolution on PAL and colours looked more real and sort of colder as a result. NTSC looks somewhat more "orange" like you could see it had a warm tone that was comfortable but not quite accurate. It often made NTSC look a bit jarring when someone cut to a feed from a US source as the image would turn sort of warm and less sharp.

PAL & SECAM are technical different but they look absolutely identical on screen, unless you had a week signal, in which case SECAM behaved differently.

NTSC being oldest, had more glitches notably issues with hue control, which PAL solved and SÉCAM isn't technically susceptible to in the first place. Also European TV settled on 625 lines as opposed to 525. There were a few previous systems, like the very early Marconi 405 line system used in the UK, which was the first electronic TV system and French 819 line systems and at least one other, before that standard 625 line approach was universal.

Brazil managed to merge the two, with PAL colour overlaid on a 525 line US originated baseband luminance system.

You could use NTSC, PAL or SÉCAM to encode colour on any existing B&W system btw.
 
Quite a interesting discussion.  This is one of the things I love about this site, free ranging discussions, no moderator to slap someone down from going off topic.

 

In terms of metric vs. imperial I use a bit of metric and a lot of imperial.  I do a fair amount of baking and convert everything to grams. Quicker, no extra stuff to wash and better granularity, an ounce is just too large, using it gets into fractions, much easier to say 400 grams of sugar  than  14.1 oz. a recipe turns out exactly the same every time.

 

The rest - it's just what you learn.  I know 75 mph on the highway, but could learn that is 120 kph.  I'm comfortable at 68 degrees, but could learn it's 20 degrees Celsius.  At this point I see no value in converting, historically it might have made sense.  With smart tech it's easy to ask Alexa to convert as it is with a smart phone when the need arises. Repair garages are equipped with both sets to tools, a bit of added expense but not much.  I can flip my dash readout to Kph when I go to Canada, so technology has made a radical change for the US moot.

 

When I was younger I'd would have ben all for conversion, now it's why bother....
 
Here in Ireland we changed from mph to km/h in 2005.

Most things, including distance signs, had been moving to metric since the early 1970s, so this was the last big visible step.

It had actually been very awkward to have speed limits in miles and distance signs in km. If you're on a Motorway doing 120 and you're going 200km, at least you now know it will take roughly 100 mins. Trying to do that calculation with mixture of metric distances and imperial speeds was very unintuitive.

The major speed limits changed:

30mph zones (urban) - became 50km/h
40mph zones - became 60km/h
60mph (N-roads [highways?] - became 100km/h
70mph (Motorway [expressway M and some N roads] became 120km/h

The general speed limit on secondary roads was reduced from 60mph to 80km/h

Various other limits are used, like city centre/town centres are often 30km/h and you'll get other odd limits.

It took a few weeks to get used to it.

35,000 signs were replaced and 25,000 extra were added. They just installed the signs over a few weeks, they were covered had loads of county & city council and roads agency people ready to do the switch over one weekend. New signs unveiled and old ones either removed or had blanking stickers applied until they could be.

Existing cars have had dual mph and kph speedometers for several decades, so there was backwards compatibility and cars from 2005 on are kmh only speedometers, the same as continental Europe.

Within a few weeks you just tend to get a feel for it and mph seems very strange when I encounter it On trips to the UK.
 
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