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    #46
    Originally posted by Frank DuVal View Post

    SO, I get a cooling system rated in killowatts. How does that help me wire it? DIvide KW by system voltage to get amps? I thought so, it is still read the nameplate! Now I have a product with TWO killowatt ratings. That is not confusing?

    Much clearer with Killowatts being the amount of electricity consumed and the cooling ability in BTU or tons.

    Same with motors/engines rated in horsepower. I know what a 300 HP engine does in a car. I have to convert to use KW of engine.
    When both input and output ratings are in kilowatts, and specified so you can see which is which, it TELLS YOU SOMETHING about what is happening within the machine. It shows you the inputs and outputs, so you can compare both power ratings on the same scale of numbers. Having separate units for electric power, mechanical power, thermal power, etc, obscures this information. Physical reality is that no machine is 100% efficient at turning the energy we put in the machine into energy we want out of it.

    We expect a motor to have some power lost to heat, and we expect an engine of the same capacity to have a lot more power lost to heat and exhaust. Refrigeration systems are a different stroy, because they extract power from either the cooling space, or surrounding cold environment in the case of heat pumps, and generally can "pump" more thermal power from cold space to hot space, than the electric power needed to supply them.

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      #47
      Of course, lots of dimensions are still nominal rather than actual.

      -Jon

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        #48
        Originally posted by PaulMmn View Post
        And those 50.8 x 101.6 studs-- that's a 'rounding error.' Let the lumber yards loose, and they'll be 50 x 100 studs. The rest will be lost because they were''planed after drying.' Space those studs 400 cm apart (that's a hair less than 16") or 600 cm (~24").
        The metric-using countries, identify dimensional lumber by actual size, rather than nominal. What a concept!

        The closest equivalent of 2x4, is 35x90, and their lumber is close in actual size to inch-nominal standard lumber sizes, rounded to multiples of either 5 or 10 mm. Plywood and drywall come in 1200 mm x 2400 mm, which is what a 4'x8' sheet would be, when rounded to the nearest 100 mm. Multiples of 100 mm, such as 400 mm and 600 mm, are common for standard spacing of studs, joists and rafters.

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          #49
          Originally posted by Frank DuVal View Post
          No confusion??????????????
          You must be young!

          SO, I get a cooling system rated in killowatts. How does that help me wire it? DIvide KW by system voltage to get amps? I thought so, it is still read the nameplate! Now I have a product with TWO killowatt ratings. That is not confusing?

          Much clearer with Killowatts being the amount of electricity consumed and the cooling ability in BTU or tons. ...

          In the mean time, I need some device boxes to fit those 50.8 x 101.6 studs. Easier, right!
          If using multiple different units to measure the same thing wasn't confusing, this thread wouldn't exist.

          Born 1959.
          You'll wire it the same way you do now: by the CURRENT consumption on the nameplate. Minimum circuit capacity, maximum fuse size. Not by the power it delivers and not by the power it consumes.

          My forecast: By the time we finally drop the British system of weights and measures, we will also be in the habit of displaying the ACTUAL dimensions of things. One (?) of the big box stores is already doing this as a result of a lawsuit claiming it was false advertising to call a wall stud a "2x4" when in reality, it's actually 28% less than that. But I ain't holding my breath; it takes 50-100 years for the building industry to adopt a "new" idea. (for example: the far-superior Torx hexalobular screwhead (ISO 10664) was developed in 1967)

          Originally posted by Frank DuVal View Post
          Stuck with? We did stick with HP. Youse guys changed! All the old British iron is rated in horsepower. Even taxed on Tax Horsepower back then. Hence way the long stroke small diameter cylinders were all the rage back then, as Tax Horsepower was derived from a math formula instead of actual performance data....
          Ah, yes ... yet another example of a cockamamie indirect measurement. Not only is it peculiar and not terribly reality-based, (British tax horsepower is a measure of the total area of the piston tops) but it's also defined differently in different jurisdictions.

          This particular example has nothing to do with which unit system was selected; it's an example of a rule imposed by people who just didn't have a clue about the art & science of measurement itself. It would have been equally stupid -- and had the same unintended consequences -- had it been defined in SI.
          https://en.wikipedia.org/wiki/Tax_horsepower

          Originally posted by winnie View Post
          Of course, lots of dimensions are still nominal rather than actual. ...
          That should be one of the FIRST things corrected. It's SO much fun to try to explain to newbies that you can't fit a "3-inch" pipe in a "4-inch" stud space.

          Originally posted by Carultch View Post
          [The refrigeration ton] only accounts for the cooling effect as 1 ton of 0°C ice turns into 0°C water, i.e. the latent heat of fusion. ... It doesn't account ice that starts below 0°C having to absorb energy to get to 0°C in the first place, and it doesn't account for any temperature gain the water has after it melts.
          Right you are. But I doubt anybody was being that precise in the 1800s, when the refrigeration ton was defined.
          I also doubt it caused much of an error in practice. Natural ice -- harvested from ponds & rivers and capped with an insulating layer of snow -- was probably never much below 0°C, and since it's cold in an icehouse, the meltwater was probably never much above 0°C when it was discarded.
          Last edited by drcampbell; 11-16-19, 09:31 AM.

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            #50
            Originally posted by drcampbell View Post
            If using multiple different units to measure the same thing wasn't confusing, this thread wouldn't exist.

            Born 1959.
            You'll wire it the same way you do now: by the CURRENT consumption on the nameplate. Minimum circuit capacity, maximum fuse size. Not by the power it delivers and not by the power it consumes.



            Right you are. But I doubt anybody was being that precise in the 1800s, when the refrigeration ton was defined.
            I also doubt it caused much of an error in practice. Natural ice -- harvested from ponds & rivers and capped with an insulating layer of snow -- was probably never much below 0°C, and since it's cold in an icehouse, the meltwater was probably never much above 0°C when it was discarded.
            Interesting that you are using centigrade.......but your weather is given in Fahrenheit..........

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              #51
              I'm almost completely bilingual.
              I also live just 16 km north of the Canadian border, and often travel there and/or tune into Canadian broadcasting.

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                #52
                Originally posted by drcampbell View Post
                I'm almost completely bilingual.
                I also live just 16 km north of the Canadian border, and often travel there and/or tune into Canadian broadcasting.
                Most unit conversions I can do mentally. Maybe that makes me bilingual too?
                I've been to Canada numerous times. From St Johns Island off the east coast to Vancouver Island off the west coast. In fact, it took longer to fly from London to Ottawa than it took to fly across Canada.

                Mostly variable speed drives on cranes on icebreakers. Getting back to units, they were rated at 275kW

                I digress.

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                  #53
                  Originally posted by Besoeker3 View Post
                  ... it took longer to fly from London to Ottawa than it took to fly across Canada. ...
                  Typo? I would think it would take less time to cross the Atlantic than to cross Canada. (I presume you're not referring to London, Ontario or London, Ohio) There are many, many jokes about the vastness (and flatness) of the Canadian prairies and many, many awe-struck reports about the vastness (and grandeur) of the Canadian Rockies.

                  The Winnipeg comedy festival is one of the best on Earth. Likely because Manitoba winters give you lots of time to huddle indoors and polish your material.

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                    #54
                    Originally posted by Frank DuVal View Post

                    No confusion??????????????

                    You must be young!

                    SO, I get a cooling system rated in killowatts. How does that help me wire it? DIvide KW by system voltage to get amps? I thought so, it is still read the nameplate! Now I have a product with TWO killowatt ratings. That is not confusing?

                    Much clearer with Killowatts being the amount of electricity consumed and the cooling ability in BTU or tons.

                    Same with motors/engines rated in horsepower. I know what a 300 HP engine does in a car. I have to convert to use KW of engine.

                    Cubic inch to liters is not too hard, a factor of 60.8. After 35 years most have learned what size engines are in liters.

                    Maybe in another 35 years when we are gone young guys will speak of KW in cars, but not yet here!

                    By then cars will be electric and KW will seem so more applicable anyway.

                    In the mean time, I need some device boxes to fit those 50.8 x 101.6 studs. Easier, right!
                    IEC electric motors are rated in kW - it is the output rating though.

                    Knowing displacement of an ICE doesn't tell you the output rating, though if you know much about them it likely gives you a ballpark estimate of it's rating.
                    I live for today, I'm just a day behind.

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                      #55
                      Originally posted by drcampbell View Post
                      Typo? I would think it would take less time to cross the Atlantic than to cross Canada. (I presume you're not referring to London, Ontario or London, Ohio) There are many, many jokes about the vastness (and flatness) of the Canadian prairies and many, many awe-struck reports about the vastness (and grandeur) of the Canadian Rockies.

                      The Winnipeg comedy festival is one of the best on Earth. Likely because Manitoba winters give you lots of time to huddle indoors and polish your material.
                      You are right again.

                      This might give you, and others, an idea of what I did............I've removed company names so maybe the mods will permit it.



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