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  • Georgineer
    replied
    Originally posted by J Tiers View Post
    These days, about the only function of the polarized plug is to make sure the center pin on a lamp socket is the hot connection (and NOT the outer screw portion).
    Which was never an issue with the UK's two-pin bayonet cap sockets. Unfortunately, the inferior Edison screw fitting is becoming more and more common in the UK on cheap imported goods.

    George

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  • RichR
    replied
    Originally posted by J Tiers View Post
    These days, about the only function of the polarized plug is to make sure the center pin on a lamp socket is the hot connection (and NOT the outer screw portion).
    Not true. Some wallwarts have polarized plugs, presumably to prevent you from plugging more than one into a duplex outlet.

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  • J Tiers
    replied
    Originally posted by hermetic View Post
    ....... Ensuring correct polarity connection is vital for safety, though not as much as it used to be in the days of valve radios and amplifiers where, if the plug was inserted the wrong way round, the chassis of the amp or radio would be live at the supply voltage. Many musicans have been killed this way!!
    That is SO out of date everywhere...... There is no national standard I am aware of that will accept a connection of the chassis to the neutral, and has not been for at least 60 years.

    EVERY standard treats the neutral as a live wire, with the same insulation requirements as the nominal hot wire. In countries using Schuko plugs, there is no polarizing, the plug goes in either way. The US has had polarized plugs for a long time, on anything that is not double insulated. Many double-insulated items still have different sized prongs. And, anything not double insulated will have a 3 wire plug that is self-polarizing.

    Most cases of problems with musical equipment have been due to using 2 wire plugs, AND having the "polarizing" switch. That switch connects a capacitor to either the hot or neutral conductor, the other end of the capacitor goes to the chassis. In old equipment, those capacitors were not UL recognized safety types, and would short sometimes. Obviously that could make the chassis "hot". That is also not permitted, nor has it been for at least 40 years.

    These days, about the only function of the polarized plug is to make sure the center pin on a lamp socket is the hot connection (and NOT the outer screw portion).

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  • MattiJ
    replied
    Originally posted by willmac View Post
    Yes - reversed polarity was a big safety issue and still is in countries that don't use polarised plugs universally.

    Another plus is that 13amp plugs are very robust. You can't easily bend the pins on one of these, but it is ridiculously easy to do so on some other nations plugs.
    Whaat? Anything with live chassis is now probably at least 60 years old and even those were reasonably safe by standards of that time if they were designed for "non-polarized plug" countries.

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  • willmac
    replied
    Originally posted by hermetic View Post
    Ensuring correct polarity connection is vital for safety, though not as much as it used to be in the days of valve radios and amplifiers wher, if the plug was inserted the wrong way round, the chassis of the amp or radio would be live at the supply voltage. Many musicans have been killed this way!!
    Yes - reversed polarity was a big safety issue and still is in countries that don't use polarised plugs universally.

    Another plus is that 13amp plugs are very robust. You can't easily bend the pins on one of these, but it is ridiculously easy to do so on some other nations plugs.

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  • hermetic
    replied
    The fuse in the plug protects the cord and the appliance, and is sized specifically to the appliance it is fitted to. In your system, a table lamp, which we would fuse at 3 amps, you would connect to a circuit fused to 10A or 16A. UK ring main circuits are always fused at 30 amps, or have a 32 amp circuit breaker, thus individual appliances are protected by the fuse in the plug, and the ring main itself is protected by the 30A fuse, or the 32 amp circuit breaker. Ensuring correct polarity connection is vital for safety, though not as much as it used to be in the days of valve radios and amplifiers wher, if the plug was inserted the wrong way round, the chassis of the amp or radio would be live at the supply voltage. Many musicans have been killed this way!!

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  • MattiJ
    replied
    Originally posted by hermetic View Post
    BS1363 introduced the worlds first shuttered socket ( Although there was an earlier shuttered socket, and a fused plug, introduced by Crompton also in the UK), meaning it was impossible to insert anything in to the holes unles it was a plug, and provided a plug with a fuse , the rating of which matched the appliance it was fitted to. This combination of one size plug and socket for all appliances was introdued in 1947, and is still in use today.
    OK, you got the shuttered sockets early on and that's good, in here they have been common only for last 20 years or so.

    AFAIK UK plug fuse is to protect the appliance cord, not the appliance itself because your crazy big ring circuit fuses. In rest of the world we don't need plug fuses since we have branch wiring with 10A or 16A fuses vs. 30A or sometimes 60A fuses used in UK ring wiring circuit.
    Claimed benefit of the UK system is less copper needed in ring wiring vs. branch wiring, probably somewhat true but I am not sure how big the savings are...

    Live and neutral reversion protection sounds good in theory but I don't see that as a big deal after all?(save 5 pennies on single pole switch instead of 2-pole?)

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  • willmac
    replied
    Yes, and plugs with a generous earth pin, which ensures that live and neutral cannot be reversed. Some other systems still do not follow this principle.

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  • hermetic
    replied
    BS1363 introduced the worlds first shuttered socket ( Although there was an earlier shuttered socket, and a fused plug, introduced by Crompton also in the UK), meaning it was impossible to insert anything in to the holes unles it was a plug, and provided a plug with a fuse , the rating of which matched the appliance it was fitted to. This combination of one size plug and socket for all appliances was introdued in 1947, and is still in use today.

    Leave a comment:


  • MattiJ
    replied
    Originally posted by hermetic View Post
    as anyone from the UK who has travelled anywhere in Europe will tell you what a far superior system the UK has since the introduction of the BS1363 13amp plug and socket .
    Superior? how?

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  • hermetic
    replied
    This whole thread is very similar to Bishops arguing over how many angels can dance on the head of a pin. As far as I can ascertain, none of the changes that have ever supposedly occured in any measurement system has ever made any difference at the practical level, no one has thrown away measuring equipment because it was no longer standard The 1kg platinum cylinders lose atomic mass at a very gradual rate, and so may have to be replaced because they no longer weigh 1Kg, not because the weight of the kg is changing. The Inch was standardised hundreds of years ago, and the original "standards are still stored in London. When the British first went to America, copies of the standards went with them, thus standardising measurement in the new world. Unfortunately the US became independant before the reform act of 1820, and so kept all the old British standard weights and measurements Whilst the uk moved on to a rigidly standardised system. Like most of what comes from Brussels, we have had several instances of EU weights and measures nonsense, which has been enforced all over Europe in a failed attempt to "standardise". In the electrical field, we have now had two complete changes of cable identification colours, in order to "Harmonise" colours . Why this happened is anyones guess, as anyone from the UK who has travelled anywhere in Europe will tell you what a far superior system the UK has since the introduction of the BS1363 13amp plug and socket . The biggest "harmonisation" turkey was harmonisation of voltage throughout Europe. The nominal voltage in the UK is 240V, the nominal voltage in Europe is 230V, hence appliances are labelled "230/240V" It was proposed that, although there was to be no actual change to the UK voltage (for obvious reasons! see Ohms law) From a certain harmonisation date we would all in the Electrical industry, refer to UK mains voltage as "230V" They say that the air movement caused by massed middle digits raised towards Brussels caused a twister in Oklahoma...........Thank god for Brexit!!

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  • Jaakko Fagerlund
    replied
    Originally posted by Weston Bye View Post
    An awkward standard indeed. This put me in mind of a fact related to me some time ago by my son-in-law, an environmental engineer. Seems that the planet is still exhibiting the effects of the last glacial period 12,000 years ago, specifically the portions of the crust weighed down the massive glacial ice sheets were crushed down and the areas at the perimeter of the ice fields was extruded up. That was then, but with the subsidence of the ice, the land masses have been returning to "normal" even to the present day.

    See here:https://www.unavco.org/highlights/20...l_rebound.html

    This has ongoing ramifications when attempting to rely on geological features when establishing measurement standards.
    Yes, originally defined as such and nowadays has no relation to the geological features. It isnow defined as the distance light will travel in a vacuum in 1/299792458 second.

    And the mass is also being redefined to a different base standard,don't know when it is ready or in use.

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  • Weston Bye
    replied
    Originally posted by Paul Alciatore View Post
    ...the length of the meter was originally defined as 1/10,000,000 of the distance from the North Pole to the equator. Talk about an awkward standard. It has also been adjusted over the years...
    An awkward standard indeed. This put me in mind of a fact related to me some time ago by my son-in-law, an environmental engineer. Seems that the planet is still exhibiting the effects of the last glacial period 12,000 years ago, specifically the portions of the crust weighed down the massive glacial ice sheets were crushed down and the areas at the perimeter of the ice fields was extruded up. That was then, but with the subsidence of the ice, the land masses have been returning to "normal" even to the present day.

    See here:https://www.unavco.org/highlights/20...l_rebound.html

    This has ongoing ramifications when attempting to rely on geological features when establishing measurement standards.

    At the risk of derailing this thread, I wonder if the glacial rebound factor has been considered in the climate change debate when projecting sea level changes and assigning causes and blame, particularly on the northeast coast of the United States, where actual measurements document "sea level rise". Or is it subsidence of the land mass?

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  • Hopefuldave
    replied
    Originally posted by fjk View Post
    "A man who has one clock always knows what time it is,
    A man who has two clocks never knows what time it is"
    - Ancient Vulcan Proverb
    In my working life, "never knows what time it is to better than 7 nanoseconds"...

    Dave H. (the other one)

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  • The Artful Bodger
    replied
    Originally posted by J Tiers View Post
    Just another elitist way to change things around!

    It would work as well to say km per liter, and probably make more sense, but because folks in the US would do that, it HAS to be expressed the other way, because folks in the US are, well, just WRONG, and of course nothing can be done the way THEY would do it. That's what happens when you get snobbish geeks in charge. The kind of folks who argue for hours about the technique of pouring wine, grinding beans and brewing coffee, or the technically "proper" way to do anything, really.

    Well yeabut...litres per 100kms is a measure of fuel consumption (i.e. the measure of fuel consumed per distance) whereas kilometres per litre would be a measure of distance travelled (i.e. measure of distance travelled per fuel consumed).

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