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  • How much power is needed here?

    I'm trying to figure out what size fused enclosed safety switch and what Amp fuses are needed for this. Below is the info I have to work with.

    Volts: 230
    Watts: 50,000
    Phase: 3 delta

    This is for a boiler in a commercial building. Please remember this is a three phase setup. Also, being resistive heating elements I don't see where we need to get into power factor and the like. Figure on unity 0.0 power factor, please.

    I need to know the Ampere draw and the correct fused safety switch and fuses to use for this. Remember this will be in use 24/7 and the boiler will see a heavy load so the elements will be pretty much a continuous load.

    The boiler wiring will be 3 conductors with ground. L1, L2, L3 and ground. There is no need to think about a control circuit. Everything is self contained as far as controls go. It is a hot water and not a steam boiler for what that matters.
    Last edited by Woussko; 07-13-2009, 02:30 AM.

  • #2
    Re: How much power is needed here?

    Ohms law= Watts devided by volts= 218amps.
    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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    • #3
      Re: How much power is needed here?

      218 A is correct for line current but phase current will be 218 / √3 =125.8 A, add the saftey factor of 125% and you have 157.3 A
      I believe the next common size of breaker is 175A so the wire size would be 00.

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      • #4
        Re: How much power is needed here?

        Phase and line current have always thrown me off.

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        • #5
          Re: How much power is needed here?

          Originally posted by papadan View Post
          Ohms law= Watts devided by volts= 218amps.
          But we need to remember this is 3 phase power we are dealing.
          Last edited by Woussko; 07-14-2009, 12:15 AM.

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          • #6
            Re: How much power is needed here?

            60a
            ---------------
            Light is faster than sound. That's why some people seem really bright until you hear them speak.
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            “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
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            • #7
              Re: How much power is needed here?

              wbrooks's has it

              50,000 divided by 230 divided by 1.732

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