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    #16
    110707-1048 EDT

    I made a mistake in supporting the $1 per hour charge. In my mind I may have been thinking of $1 per KWH. In any event the real cost of electricity for the area or conditions (gasoline powered generator) needs to be used to arrive at a price.


    kwired:

    i somewhat support your loose use of power relative to what you were trying to explain. I think in loose conversation it is easier to say power than energy. We usually speak of power companies, but the use of energy companies is becoming more common.

    .

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      #17
      Originally posted by kwired View Post
      I knew that, I was focusing more on the fact that he was trying to multiply watts by 1.73 to convert to three phase values.

      A better statement is that power and/or energy is same for a given amount of work (assuming same efficiencies of equipment)
      Energy and work are equivalent quantities.

      Power is not the same as work.
      Power is the rate of doing work.


      In SI (metric) units, the unit of work (and energy) is the Joule.
      One Joule is a force of one Newton moved through a distance of one metre.
      Do that in a time of one second and that gives you the rate of doing work which, in this case in one Watt. Which also happens to be one Amp times one Volt. Which also happens to be one of the reasons I like using SI.


      For Imperial, if you move a force of one lb(f) through a distance of 550 feet or 550lbf through a distance of one foot, you will you will have done 550 ft-lbf of work. Do either in a second and your rate of work will be one horsepower. Or about 746 Watts.
      Si hoc legere scis nimium eruditionis habes.

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        #18
        I think that before getting too far off on tangents, just stick to the facts you have and don't add too many things into the mix. Those are that
        1) Motor electrical power consumption = 746W per HP, plus losses,
        2) The only information you have about the motor is the full load HP, you don't know what the actual load is on the motor.

        But it's a relatively safe bet it's probably around 80-90% loaded, that's a good design practice. So since you don't know how loaded the motor is, but you also don't know the efficiency (losses), you can pretty much trade the unknown loading for the unknown losses and call it a wash.

        So for NON-REGULATED energy charges, I would just go with the 15kW and if you want to charge for 1 hour of work, that's 15kWh. Keep it simple.

        If you want to be gnat's ass accurate, buy a kWh meter.
        __________________________________________________ ____________________________
        Many people are shocked when they discover I am not a good electrician...

        I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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          #19
          Originally posted by Jraef View Post
          I think that before getting too far off on tangents, just stick to the facts
          But....
          power and/or energy is same for a given amount of work
          is not, in fact, a fact.
          Just thought I'd clear that one up.
          Si hoc legere scis nimium eruditionis habes.

          Comment


            #20
            Originally posted by K8MHZ View Post
            That is not legal in most states as the sale of electricity must be overseen by the state's Public Service Commission.
            You can still install a meter to monitor kwh and in most areas you can charge what you paid for the electricity.

            In other words the illegal part would be reselling the power for profit.
            Last edited by iwire; 07-09-11, 03:35 AM.

            Comment


              #21
              Originally posted by Besoeker View Post
              But....

              is not, in fact, a fact.
              Just thought I'd clear that one up.

              The clear-up you offered was apropos and nothing you said was incorrect.

              My comment on tangents wasn't specifically directed at you, it was meant for all of us, just coincidental to being after your post. My concern was that since we ALL tend to go off on tangents, the OPs sometimes get lost in them and too far afield from getting the answer they were looking for.
              __________________________________________________ ____________________________
              Many people are shocked when they discover I am not a good electrician...

              I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

              Comment


                #22
                Originally posted by Jraef View Post
                The clear-up you offered was apropos and nothing you said was incorrect.
                It wasn't a correction to something I posted.
                It was in response to this incorrect statement by another poster:

                A better statement is that power and/or energy is same for a given amount of work
                Si hoc legere scis nimium eruditionis habes.

                Comment


                  #23
                  Originally posted by iwire View Post
                  You can still install a meter to monitor kwh and in most areas you can charge what you paid for the electricity.

                  In other words the illegal part would be reselling the power for profit.
                  that is the way the law works here as well.
                  NEC 1968 and 1948

                  Comment


                    #24
                    Originally posted by iwire View Post
                    You can still install a meter to monitor kwh and in most areas you can charge what you paid for the electricity.

                    In other words the illegal part would be reselling the power for profit.
                    I think laws pertaining to RV parks address how this works. For manager owned meters, in one example regulation I've read, the user has the right to ask for validity of calibration for the duration of billing period, provided with means of contesting the charge and outlines how the charge maybe allocated.

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                      #25
                      I was curious about state laws but couldn't phrase a google search well enough to find anything. I e-mailed Davidge Controls (they sell sub-metering equipment), they said only California and Maryland regulate sub-meters, I have the feeling I didn't phrase my question well enough for this answer to apply.
                      Think for yourself, while its still somewhat legal!
                      Clarkesville, Georgia

                      Comment


                        #26
                        Install a KWH meter. IF legal in your area, resell.

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