Nice overview of the 240v US electrical system

[iej]

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.

 

[iej]

Definition of metric units

Metric units aren't defined by Le Grand Kilo anymore as it's not a suitable way of ensuring that you get a perfectly reliable reference.

It's currently defined by taking the fixed numerical value of the Planck constant h to be 6.62607015×10−34 when expressed in the unit J⋅s, which is equal to kg⋅m2⋅s−1, where the metre and the second are defined in terms of c and ΔνCs.

That may sound complicated, but it gives you a unit that's usable for extremely accurate scientific use that's not just based on some lump of metal.

The meter is defined as the length of the path travelled by light in vacuum during a time interval of
1/299 792 458 of a second.

The major advantage of the metric system for end users is that the units are interrelated and easy to calculate with. You're not left dealing with base 12 or base 16 and fractions and all sorts of crazy historical units. Familiarity doesn't mean they're easy.

I mean we used a currency, the Pound, that until the early 1970s had 240 pence in each pound and 12 shillings and prices were written like £1 2s 3 1/2d = One pound, two shillings and 3 and a half pence. People thought that was fine and you had holdouts claiming decimal money was far too complicated. They also used tons of jargon like Half Crowns, Thruppeny Bits and then also used Guineas (one pound and one shilling!)

Also the A standard of paper used in Europe makes sooooooo much sense! I have no idea how Americans work with that arbitrary system of paper sizes when dealing with things like say a photocopier to enlarge something.

Take A0 (large format drafting paper). Fold it in half and you have A1
Fold A1 in half and you have A2
Fold A3 in half and you have A4 (the stuff we mostly put in printers)
Fold A4 in half and you have A5

And so on.

 

[sudsmaster]

Not sour grapes at all.

 

But I only wanted to point out that there are two sides to every debate, and that there are definite cons to the metric system.

 

Again, I have a university degree in science and of course I appreciate and value the metric system. But like any system it's got its own drawbacks. Mainly from being designed from a science lab point of view, instead of an every day at home point of view.

 

Is the metric system better for scientific purposes? Of course.

 

The articles I posted argue however that it is less than ideal for every day purposes. Not that it can't be made to work.

 

 

[gizmo]

Yeah, but SudsMaster...with all due respect, the arguments you posted hold no water. The "drawbacks" listed are nonsense. They are not inherent problems in metric, they only indicate unfamiliarity with common household use of metric measures.

You might feel that inches and feet are somehow "natural" but that is just because you are used to those measurements. It is no harder to understand that I am six feet tall or 1.8 metres tall. That I would like to lose 10 pounds or 5 kg. A 1.2 kg chicken is small and a 1.8 kg chicken is large. 200 grams is a medium size steak or a large piece of fish. a 500g loaf of bread is smallish and a 750g loaf is large. I have no idea what the equivalents are in imperial because these measures are what is familiar to me.

Temperature - for me, very cold day is 5 degrees. a cold day is 10 degrees. a cool day is 15 degrees. a mild day is 20 degrees. a warm day is 25 degrees. a very warm day is 30 degrees. a hot day is 35 degrees. A horribly hot day is 40 degrees. You could ask a person from Sweden for their equivalent list and they would put the same descriptors to colder temperatures - because they are used to colder temps than I am, we are both using metric. So to mangle an old expression "familiarity breeds content" - you are comfortable with what you are used to and you see its own internal logic, but that doesn't mean it is better. What you listed as "drawbacks" for metric are really only "unfamiliarities" for a person used to imperial measure.

Don't get me started on shoe sizes - in Australia shoes are sold in 3 size systems - US, UK/Australian and European. I still have to try on every shoe I buy - I can't be confident a size 10 AU will fit, it might be 10 1/2 or an 11 in some brands. I can be a US 11 or 12. European sizes seem to go in smaller increments but I have never paid much attention to them - they are the "oddball" measure here. Why can't we just measure how long and wide our feet are in centimetres? Some online stores now do just that - you measure your foot in cm and they send you the shoe that fits your foot. But the box will be marked in one of the 3 silly systems.

I do however concede that willies will probably always be measured in inches. I don't think we will ever convince size queens to start chasing that elusive 25 cm.

 

[iej]

The biggest issue, and I see it in the UK more than here is where things were moved to metric but clung to traditional quantities like pints and pounds as the size of containers or packs. So instead of going with even number metric units like say 500g of butter, they're selling 453g (a conversion of a lb) and then concluding that the metric system is too complicated because they're just using oddball imperial measures translated, giving very awkward numbers.

 

[donprohel]

Convenience and shoes size

@sudsmaster
If I have to put 6 objects at the same distance within a space 13 m and 29 cm wide, I take a calculator, divide 13.29 / 7 = 1.898571429 and I know that my objects will go at 1 m 89 cm and 8 mm (or 189.8 cm) from each other, with an error of less than 1 mm for each object.
With one single division.

Now do the same with a 13' 2” 9/16” space and tell me how much calculation you need.

@gizmo
Just in case: the Japanese shoes size is the length of the foot in centimetres. Maybe this helps a little...

 

[sudsmaster]

Not User Friendly

Again, the articles I posted represent the opinions of the authors and not necessarily my opinions.

 

However I think they make a valid point about the divisibility of the American conventional system, for linear measurement, which is base 12, not base 10. And, when I fill a standard coffee cup, I know it will be 8 oz. I have no idea how many tenths of a liter it might be. And the point about the awkward nomenclature about weights between grams and kilograms, milliliters and liters, etc. I think are also valid. As is the comment that the deciliter is basically a totally useless term. It is all scientifically valid, but not what we these days would term "user-friendly".

 

 

 

[rolls_rapide]

Teletext

The BBC migrated over to the MHEG5 digital version with 'BBCi', later called 'Red Button'. It never quite lived up to the breadth and scope of the old analogue BBC 'CEEFAX' teletext service, although in the early days of 'OnDigital' DVB-T, the BBCi service carried pictures. Download to the receiver was s-l-o-w. They rejigged it, pictures went by the wayside, and the service became a bit snappier in operation.

Recently, the BBC wanted to switch the Red Button text service off too - but there was a humongous hue and cry from various charities, politicians and the general public. The BBC have currently 'paused' that action, pending review. It is actually quite a useful service, catching up with news whilst a programme plays out in the background.

ITV had the analogue 'ORACLE' text service. That was replaced by analogue 'TELETEXT'. Then they went digital. However, ITV decided to end their digital text service early, incurring the wrath of Ofcom.

Channel Four had '4-TEL', but I seem to remember that it was integrated into 'Teletext' similar to ITV. They probably shared the same basic service, with '4-Tel' tweaking to certain pages.

I have to say that I was rather fond of the old analogue teletext services. They carried news, sport, weather, recipes, quizzes, addresses and info for relevant programmes, television listings, and artwork. They even had computer software downloads.

 

[rolls_rapide]

Imperial versus Metric

There seemed to be no problem with British and French engineers designing and making 'Concorde'.

 

[sudsmaster]

I seem to remember some spacecraft having a big problem because two different measurement systems were used to build it and they were not reconciled.
 

"In September of 1999, after almost 10 months of travel to Mars, the Mars Climate Orbiter burned and broke into pieces. On a day when NASA engineers were expecting to celebrate, the ground reality turned out to be completely different, all because someone failed to use the right units, i.e., the metric units! The Scientific American Space Lab made a brief but interesting video on this very topic."

How NASA Lost a Spacecraft From a Metric Math Mistake | SimScale

How NASA lost a spacecraft due to a mistake with metric units and unit conversion. Learn about the Mars Climate Orbiter incident.

www.simscale.com

 

[eronie]

Hubble space telescope. They messed up the mirror.

 

[sudsmaster]

The Hubble mirror was indeed messed up, but it had nothing to do with metric vs. US Customary measuring systems.

Rather, it was human error during the assembly of the apparatus used to establish the curve to be ground into the primary mirror. As best as I can tell, an end cap was left in place during the alignment process which put the curve off by 1.3mm, which in such optics is a huge error.

This error was not detected before launch because the completed telescope was not tested as a total assembly after the grinding error.

https://www.quora.com/Is-it-true-that-the-initial-problem-with-the-Hubble-Space-Telescope-is-that-they-had-the-2-lenses-made-at-Specsavers-on-a-buy-one-get-one-free/answer/Bill-Otto-5

 

[sudsmaster]

Let's not even get into three phase vs single phase power... LOL...

Although as I understand it, three phase is superior when it comes to powering motors.

 

[gizmo]

awkward nomenclature

Where metric is in common use, each language group comes up with its own jargon to make the metric terms suit their culture.

Australians are very big on abbreviations, to a degree that makes many Brits think we are somewhat childish in our language.

Common metric terms in spoken Aussie English...
"Mils" = millilitres or millimetres - context makes it clear which one.
"Kays" or "clicks" = kilometers
"MGs" for milligrams
"kilos" for kilograms
Cups are a metric measure - a metric cup is 250 ml so 1/2 cup is 125ml. not hard.

Don't forget that Volts and amps are metric measures too, but US citizens are familiar with them so there is no nonsense written about the difficulty of metric electricity.

I understand that one of the many things that infuriate mechanics about classic Range Rovers is that they combine Metric, AF and Whitworth bolts on the one vehicle - in fact I vaguely recall even the engine has all 3 bolt systems on it?

Yes Suds you are right, 3 phase motors are inherently more efficient than single phase induction motors, fortunately now it is efficient and inexpensive to provide phase converter circuits to give a 3 or more phase supply from a single phase power source, as are used in FP Smart Drive washers, for example.

 

[gizmo]

Japanese shoe sizes

Hi Donprohel
I had no idea about the Japanese shoe sizes - how logical!
Unfortunately for me, I bet that size 11 UK/12US shoes would be hard to find in Japan...

 

[liberator1509]

Great thread, and that’s video is great too – I like his style, just complex enough and his humour appeals too.

Following on from post #31, and proof that things can change, in Ireland we had no less than three concurrent standards for plugs and sockets! This started with the British standard BS73/BS546, a legacy of pre-independence, and common mainly in larger urban centres where electricity supplies were generally local, independent networks. The BS73 and later the BS546 standards – unfused round-pin plug and socket, in different sizes according to amperage – were found routinely in installations up to the 1950s, and thereafter in the specialist installations such as theatre lighting, with the 5amp version appearing through to today in commercial and domestic settings for separate lighting circuits, especially in hotels.

Following independence, and as the most important modernising effort of the first independent state government, a strategic effort was introduced to bring electricity to the entire country. This involved a massive civil engineering project in the shape of the Ardnacrusha hydroelectric scheme on the river Shannon and the establishment of a nationalised electricity supply board (the ESB). The latter act introduced standards for voltage and current (220v AC, 50Hz), with the hydroelectric project drawing on German (specifically Siemens) engineering. Thus, German-style wiring standards became the norm for a couple of decades – both side-earth and non-earthing two-pin plugs and sockets (Schuko precursors), and screw-in fuses.

This system prevailed for about thirty years, until a decision was made in the late 1950s to harmonise with Britain – this was pre-EU, Britain was our nearest trade partner and of course there remained the controversial state partition between Northern Ireland and Ireland. Thus the new fused three pin BS1363 was adopted in Ireland as IS401 (socket) and IS411 plug, though the voltage remained at 220v, and radial circuits retained, with RCD trippers instead of screw-in fuses. The advantages of the three-pin fused plug are a) fused protection, which can be changed in rating without changing the plug or socket, b) fixed polarity c) insulated pins (latterly) d) all sockets are earthed (grounded) and e) total incompatibility with other systems. The last point was the reason for the design, forcing change. Switched sockets weren’t required, but most people have them as a convenience, and as a ‘to be sure, to be sure’ peace-of-mind exercise. Having switches allows the appliance to be isolated without having to remove the plug (saving the agony on standing on one dropped on the floor, which is never pleasant).

The changeover did happen, though it was common until the 1970s to find houses wired with mixed standards of sockets. I well recall my grandparents’ house (a post-war rural electrification project, and wired in the late 1940s by an uncle who was a rural electrification engineer for the ESB), had a mix of earthed and unearthed Schukos in all rooms, with both 13amp IS411 and 15amp BS573 in the kitchen! The 13amp socket served the fridge (and was a commonly found combined electric cooker isolator with 13 amp outlet), and the 15amp installed for the imported 1950s Speed Queen wringer washing machine. This pattern was repeated across the country until the IS401/411 was introduced, initially for new installations, and latterly for retrofits.

It is highly unusual to find any old standard installations now, except in very old unrenovated houses. The irony is that as the UK leaves the EU, might we have been better to stick with Schuko?

 

[iej]

Arguably we should have always stuck with Schuko because we used (and still do) 220V power.
BS1363 can't even deliver 3kW on 220V.

CEE 7 (Schuko) is still referenced in IS 180 and is still an acceptable alternative standard.

One possibly would be to change to CEE 7/4 and mandate shutters.

It would take a long time to see a full change over, but assuming Brexit takes the UK out of CE marking, it will result in problems. Plugs and sockets art subject to CE marking ans the Low Voltage Directive, but anything more complex is. That includes mobile phone chargers, smart plugs, Wi-Fi extender plugs, even power strips. If they're no longer CE marked, they will potentially be illegal to import into the EU.

Also light switches etc are all required to be.

It’s likely a lot of stuff will continue to be approved to CE standards, but some may not longer bother. It’s likely also that due to changes supply chains we will be back to seeing appliances arriving with continental plugs.

Might make more sense for Ireland to just bite the bullet and change back to Schuko if Brexit is a total mess. Denmark for example has begun to move away from its odd standards in favour of French & Schuko socket outlets.

It’s a minor issue but it doesn’t really make much sense for Ireland, which isn’t a huge market - only 4.8 million and Malta and Cyprus, two micro states to continue to use an odd ball standard while being in the European single market. It’s of no real advantage to us if the supply chains are reoriented back to the continent. It would just be an awkward expense and a pointless trade barrier for no real advantage.