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Thread: Continuous Load?

  1. #1
    Join Date
    Apr 2008
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    10

    Smile Continuous Load?

    Hey guys, I am curious about something. According to article 100, a continuous load is a load that is expected to continue for 3 hours or more. But are these continuous loads?

    1) Household Electric Range/Oven
    2) Household Electric Cooktop
    3) Household Electric Water Heater

    And if so, how is that determined? (what code will tell me?)

    Thanks!

  2. #2
    Join Date
    Nov 2007
    Location
    East of 480sparky
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    1,121

    cyclical load

    i believe that those loads cycle on and off, like AC, sump or well pump and are not continuous. JMSO
    Why is it, when it comes to the NEC, the obvious is never simple and the simple is never obvious?

  3. #3
    Join Date
    Sep 2006
    Location
    Michigan
    Posts
    457
    1) No
    2) No
    3) No

    It's kinda weird I know. I had an arguement with a kiln manufacturer who's literature had the recommended over current protection sized for 100% of the full load. My arguement to him was that it was expected that these would be on for more then 3 hours at a time. He finally convinced me that these were not considered continuous loads since the heating element cycles on and off to maintain a desired temperature.

    Looking up the definition of Continuous Load it says "A load where the maximum current is expected to continue for 3 hours or more."

    So mostly I just consider lighting to be a continuous load for circuit sizing. Unless I'm told of something else in the building that is continuous.

  4. #4
    Join Date
    Nov 2007
    Location
    East of 480sparky
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    1,121

    definition

    cont. load - a load where the max current is expected to continue for 3 hrs or more. 08 nechb
    Why is it, when it comes to the NEC, the obvious is never simple and the simple is never obvious?

  5. #5
    Join Date
    Feb 2003
    Location
    Massachusetts
    Posts
    49,049
    None of those are continuous loads, however the NEC requires we treat a storage type water heater under 120 gallons as a continuous load.

  6. #6
    Join Date
    Apr 2008
    Posts
    10
    Excellent. Thanks guys!

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