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What's Wrong Here?

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  • What's Wrong Here?

    Please see the picture and then state what's crazy about the warning message. Please think about it if it isn't obvious to you. This is something you'll see around technical schools.
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  • #2
    Re: What's Wrong Here?

    Originally posted by Woussko View Post
    Please see the picture and then state what's crazy about the warning message. Please think about it if it isn't obvious to you. This is something you'll see around technical schools.
    Doesn't matter how many Ohm of resistance something is if there is no voltage applied across it.

    If it were 50,000 Ohms; it would seem like that would melt itself at any normal voltage; since it is offering like 5000 times the resistance as my clothes dryer.

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    • #3
      Re: What's Wrong Here?

      www.firstresponsedrain.com

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      • #4
        Re: What's Wrong Here?

        www.firstresponsedrain.com

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        • #5
          Re: What's Wrong Here?

          Originally posted by cpw View Post
          ...

          If it were 50,000 Ohms; it would seem like that would melt itself at any normal voltage; since it is offering like 5000 times the resistance as my clothes dryer.
          You really need to study your OHMS law...

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          • #6
            Re: What's Wrong Here?

            What's wrong here is assuming that the warning message on a resister is odd or strange. You would normally use a resister around that Ohm mark to discharge a capacitor in say a microwave oven or some other high voltage device. You use a large resister for voltage holdoff. You don't want to have the high voltage zapping across the resister terminals (and frankly coming into contact with you.)
            Cheers,
            Jim Don

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            • #7
              Re: What's Wrong Here?

              you guys are getting to technical

              i see it as 6'' of resistance

              rick.
              phoebe it is

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              • #8
                Re: What's Wrong Here?

                Originally posted by Newman View Post
                You really need to study your OHMS law...
                You're right. I am still way confused. I understand that my original post made no sense. I kind of have the following conundrum right now though:
                1. Thinner wires offer more resistance, and thus build up more heat (why you need bigger extension cords for more distance/current draw). Thus, it would seem that an increased resistance would result in more heat.
                2. I know that when you plug in two appliances you decrease the resistance (because they are in parallel). This means current goes up, and you are expending more energy. If you expend energy it eventually ends up as heat. Thus it would seam something like a dryer that is meant to produce a lot of heat should have low resistance.

                My brain hurts after thinking about that on and off; hopefully someone else can help me make peace with this.

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                • #9
                  Re: What's Wrong Here?

                  1. Thinner wires offer more resistance, and thus build up more heat (why you need bigger extension cords for more distance/current draw). Thus, it would seem that an increased resistance would result in more heat.
                  It's relative to the current (number of electrons flowing past a given point). If I have a piece of #22 wire I can put 600V on it with a low current (say 5 mA) and not have a problem. Or I could have 12V at 10 Amps and then I've got a problem. I'd be trying to push so many electrons through that thin wire that it would heat up and probably melt pretty darn quick. This is assuming we are talking about DC or low frequency AC (less than a few thousand hertz). For instance two wires of the same length and same material, but different diameters, will have different resistances, the larger diameter wire offering less resistance.

                  In plumber speak:
                  Think GPM for an idea of how Current(Amps) works
                  Think PSI for an idea of how voltage works

                  A general statement like "Thinner wires offer more resistance" is only somewhat true. The wire by itself has a fixed resistance (Ohms per foot) for its material composition and diameter at a given temperature.

                  Yes, you need a heavier gauge wire in your extension cord when it is longer to help fight voltage drop -or- you need a heavier gauge wire (smaller number = heavier wire gauge) if you need to power a tool that draws more Amps even though the distance has remained the same ( I switch from using a 1/4" drill motor to a worm-drive saw on the same cord).

                  #2. If I plug two appliances (each with a heating element say) to the same circuit they are connected to the source in parallel yes. Their combined resistance can be found using this formula:
                  Rt = (R1*R2)/(R1+R2).
                  This formula only works for two loads in parallel, if there are more a difference formula is used.

                  Sorry - outta time for this evening, long day tomorrow. I'm up at 4AM and off to work then I have a class after work so won't be back home until after 10PM.
                  ---------------
                  Light is faster than sound. That's why some people seem really bright until you hear them speak.
                  ---------------
                  “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
                  ---------
                  "Its a table saw.... Do you know where your fingers are?"
                  ---------
                  sigpic http://www.helmetstohardhats.com/

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                  • #10
                    Re: What's Wrong Here?

                    What is wrong is trying to scare people into thinking the power resistor by itself is dangerous. The size, type and value in Ohms really doesn't matter. It's not connected to anything.

                    I couldn't help myself remembering how many times I have seen a power resistor with some manor of DANGER message next to it.

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                    • #11
                      Re: What's Wrong Here?

                      Danger comes when it is connected to a circuit. Nasty burns from a resistor that size! Want to understand how hot a resistor can get, look at the cig lighter in your truck. That coil is a resistor with 12 volts run through it.
                      info for all: http://www.hoistman.com http://www.freeyabb.com/phpbb/index....wwtoolinfoforu --- "I like long walks, especially when they are taken by people who annoy me."

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