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    markwilsonparker's Avatar
    markwilsonparker Posts: 2, Reputation: 1
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    #1

    Nov 29, 2006, 10:04 AM
    Sizing amperage for a subpanel
    I'd like to run a subpanel off a 100 amp main. The sub needs to be able to handle a hot water heater, an electric dryer, a washer, an oven, and an electric stove. All but the washer require 220.

    What is the minimum size panel I need? What size wire should I use for the run? (Run is about thirty feet)
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #2

    Nov 29, 2006, 01:08 PM
    Assuming the following loads for the following appliances:

    Water heater... 4500 watts
    Dryer... 4500 watts
    Range/oven... 8000 watts (allowed min. load even thou both together may be more)
    Total load... 17000 watts / 240 volts = 71 amps

    These appliances need to be calculated at 100%, which assumes all may be on at one time together, even thou you may swear they will not.

    You will need a 100 amp subpanel protected by a 100 amp breaker in the main panel. You can use #2 Aluminum SER cable to feed the subpanel.

    I usually try to convince people to use a bit more branch circuit cable for large appliances, such as these, and get them back to the main panel, if at all possible.

    The other issue to be concerned with is will the main panel and service be able to handle this added load.
    markwilsonparker's Avatar
    markwilsonparker Posts: 2, Reputation: 1
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    #3

    Nov 30, 2006, 07:41 AM
    Thanks for your response.

    I checked again, and realized I have much more amperage on the main panel than I thought. Like 300 amps. So, the 100amp subpanel shouldn't be a problem.
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #4

    Nov 30, 2006, 03:15 PM
    Sorry, but what exactly is "like 300 amps". And that may be what the panel is rated at, but what is the connected load, that this service feeds already, plus the 100 amps you are planning to add.

    I like to be a bit more scientific than "like 300 amps". I suggest you be sure.
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