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Thread: Three Questions About 10-2

  1. #1
    DIY Senior Member molo's Avatar
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    Default Three Questions About 10-2

    1. There is 25 extra feet of it in the attic. IT supplys power to the water tank. Is this costing us more money in electriciity ($10, $50, $100 per year)?

    2. Can I the same single pole switch you use for 12/2 lighting switch to provide a disconnect for the water heater at the heater? IT WILL be 10-2 going into the switch.

    3. Does a 240 volt heater have to be tied in to a 30 amp double pole breaker or can you use a 20 amp breaker?

    TIA<
    MoLo
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    Plumber Cass's Avatar
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    The extra wire in the attic is not causing your heater to consume more energy.

    No you can't use a SP switch to kill power to the water heater.

    Use a non fused, 2 pole, quick disconnect, if you want something to kill power to the water heater without shutting the breaker. It can be located near the heater.

    The wire size determines the amperage of the breaker. 12/2 WG would use a 20A breaker 10/2 WG would take a 30A breaker 120V would use a SP breaker and 240V would use a DP breaker.

    The watt draw of the heater, which is based on the wattage of the elements, would determine the wire size needed.
    Last edited by Cass; 08-11-2007 at 12:14 PM.

  3. #3
    DIY Senior Member molo's Avatar
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    Quote Originally Posted by Cass
    The extra wire in the attic is not causing your heater to consume more energy.

    No you can't use a SP switch to kill power to the water heater.

    Use a non fused, 2 pole, quick disconnect, if you want something to kill power to the water heater without shutting the breaker. It can be located near the heater.

    The wire size determines the amperage of the breaker. 12/2 WG would use a 20A breaker 10/2 WG would take a 30A breaker 120V would use a SP breaker and 240V would use a DP breaker.

    The watt draw of the heater, which is based on the wattage of the elements, would determine the wire size needed.
    Can the non-fused, 2-pole, quick disconnect be rated for 12 and 10 gauge wires?
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
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    In the Trades Bob NH's Avatar
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    A 4500 Watt water heater requires 4500 Watts /240 Volts = 18.75 Amps.

    However, the National Electrical Code requires that continuous loads (A household water heater is defined as a continuous load.) may not exceed 80 percent of the capacity of the circuit. Therefore, you must have a circuit that has a capacity of at least 23.44 Amps.

    Standard circuits in common use are 20 Amp and 30 Amp. Therefore, it should have a 30 Amp breaker and #10 wire.

    That is not to say that it won't work with #12 wire and a 20 Amp breaker (It is drawing only 18.75 Amps.), but it will be in violation of the code.

    It would be very dangerous to use a standard light switch with a 240 Volt circuit because someone might think the circuit is turned off by the switch and get zapped when working on it because the other side of the circuit is hot.

    There are unfused 2-pole disconnects used with Air Conditioners that would work with a water heater.

  5. #5
    Plumber Cass's Avatar
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    Quote Originally Posted by molo
    Can the non-fused, 2-pole, quick disconnect be rated for 12 and 10 gauge wires?
    I don't remember their amp rating but I believe it is over 30A

  6. #6
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by molo
    Can the non-fused, 2-pole, quick disconnect be rated for 12 and 10 gauge wires?
    Disconnected are not rated in wire size, they are rated in amperage. The lugs will have a conductor size range, but this is not the rating of the disconnect.

    Most small disconnected are either 30A or 60A.


    Also, yes, a single pole switch can be used to turn off a water heater. It CANNOT however be used as the required service disconnect.

  7. #7
    DIY Senior Member molo's Avatar
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    Default is this the dconnect?

    is this it? this is for my well pump

    TIA,
    molo
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    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
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    In the Trades Bob NH's Avatar
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    Yes........... .

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    Moderator & Master Plumber hj's Avatar
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    Default disconnect

    Only you can tell, because only you can see where the wires are connected.

  10. #10
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by molo
    is this it? this is for my well pump
    Is what it? What is the question?

  11. #11
    DIY Senior Member molo's Avatar
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    THIS DCONNECT IS FOR MY WELL PUMP, i"m wONDERING IF THIS IS THE KIND i nEED FOR MY WATER TANK

    tia,
    MOLO
    "Any American who is prepared to run for President should automatically, by definition, be disqualified from ever doing so."
    Gore Vidal.

  12. #12
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by molo
    i"m wONDERING IF THIS IS THE KIND i nEED FOR MY WATER TANK
    Yes?

    I don't think you'll find one like that but that one will work. A simple little 60A "pull-out" disconnect would be the easiest.

  13. #13
    Plumber Cass's Avatar
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    Quote Originally Posted by Speedy Petey
    Also, yes, a single pole switch can be used to turn off a water heater. It CANNOT however be used as the required service disconnect.
    A single pole switch can not be used to turn off a 240v water heater.

    If the heater was 120v a quick disconnect should still be used in place of a sp switch, in my NSHO.

  14. #14
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Cass, please re-read my post. I think I clearly stated it cannot be used as a disconnect.
    For control purposes a SP switch most certainly can shut off a straight 240v load.
    Have you ever looked at the way the thermostats inside a water heater work??? They are SP.

  15. #15
    Plumber Cass's Avatar
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    Were talking about installing a sp switch outside of a W/H to cut 240v service to a W/H.

    You tell me how a SP switch shuts off both sides of a 240v circuit.

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