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Thread: advice on wire gauge for built in oven

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  1. #1
    DIY Junior Member jono604's Avatar
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    Default advice on wire gauge for built in oven

    Hello,
    I 'm in the midst of a kitchen renovation and I'd like some advice on the wire gauge for a built in oven.

    The oven is the the only electrical appliance on the circuit and supplied directly from the panel. The cooktop is gas and it's electrical needs will be supplied by a separate 15A circuit.

    The oven manufacturer calls for a 30A circuit and lists 7300W in the specs.

    I'm inclined to use 10AWG because of the 30A circuit but in some other on-line material I've seen a suggestion that says 10AWG is suitable for 30A appliances with power draw lower than 7200W.

    I'm a little bit confused. Does the 7300W rating have any impact on the wire gauge selection of is the 30A circuit the overriding factor?

    appliance specs are shown below

    thanks
    Jonathan



    Bosch oven HBL5450UC
    http://www.bosch-home.ca/en/products...?source=browse

    Energy source: Electric
    Watts (W): 7,300 W
    Current (A): 30 A
    Volts (V): 240/208 V
    Frequency (Hz): 60 Hz
    Approval certificates: CSA
    Power cord length (cm): 127.0 cm
    Plug type: Fixed connection, No plug

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    DIY Senior Member dlarrivee's Avatar
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    Well seeing how 30amps * 240 volts would be 7200watts, I think you're sort of crazy and over-thinking this whole thing...

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    DIY Junior Member jono604's Avatar
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    "over-thinking" probably.
    "crazy" ... I don't know about that. ;-)
    I'm just a first time home-owner and first time renovator who's trying to do things the right way.

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    Electrical Contractor/Instructor jwelectric's Avatar
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    You admitted to having a lose screw (crazy) in the first sentence of your original post ie: I 'm in the midst of a kitchen renovation

    Always install a piece of equipment according to any instructions included in the listing and labeling of the equipment, 110.3 (B) of the NEC

    If the installation instructions say 30 amps are what are needed then a 30 amp is what is required to be installed regardless of the math we do. The appliance has been tested by a third party who says that the 30 amp circuit is all that is needed.

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    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by jono604 View Post
    The oven is the the only electrical appliance on the circuit and supplied directly from the panel. The cooktop is gas and it's electrical needs will be supplied by a separate 15A circuit.
    I also have an electric oven with a gas top, but both draw power from the 240V connection. So, are you sure the gas top requires a separate 120V circuit?

    Quote Originally Posted by jono604 View Post
    The oven manufacturer calls for a 30A circuit and lists 7300W in the specs. I'm inclined to use 10AWG because of the 30A circuit but in some other on-line material I've seen a suggestion that says 10AWG is suitable for 30A appliances with power draw lower than 7200W.
    Sure. The 10ga wire can be used for anything *up to* 30A, and that means it is also fine with anything drawing less than your oven's possible maximum of 7300W.

    Quote Originally Posted by jono604 View Post
    Does the 7300W rating have any impact on the wire gauge selection of is the 30A circuit the overriding factor?
    No. Volts X Amps = Wattage, and circuits are rated according to amperage while total wattage used is being measured out at the electric meter.
    Last edited by leejosepho; 11-02-2011 at 04:43 AM.
    "Great minds discuss ideas, average minds discuss events and small minds discuss people." --Eleanor Roosevelt

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    Electrical Contractor/Instructor jwelectric's Avatar
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    If volts times amps equals wattage would that not mean that wattage divided by voltage give us amps.

    In the equation we know the wattage 7300 and the volts 240 so what would the amperage be? 30.4

    Now a quick look at 220.5 (B) Fractions of an Ampere. Calculations shall be permitted to be rounded to the nearest whole ampere, with decimal fractions smaller than 0.5 dropped.

    Now we are back to 30 amps just as the instructions called for

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    Plumber jimbo's Avatar
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    Here is the watts breakdown of the components in the oven:
    Bake Element Wattages cavity 1 (W): 2000 W
    Broil Element Wattages cavity 1 (W): 3600 W
    Convection Element Wattages cavity 1 (W): 2000 W


    Add that up and it is 7600 watts, but would broil ever run concurrently with bake? Would convection run concurrently with both of the other two???


    That is why the "system" is listed as 7300 watts, which is probably at the very high end....and 30 amps is fine.

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    Moderator & Master Plumber hj's Avatar
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    The circuit breaker determines the MINIMUM wire size, and #10 wire is adequate for a 30 amp breaker. That is ALL you have to know, once you determine that the unit is rated at 30 amps.

    Leejoseph; If that is a "hybrid" range, then the 120 control circuit for the cooktop is coming from the 240/120 electric supply. Even electric ovens use 120 for their circuit boards.
    Last edited by hj; 11-02-2011 at 07:04 AM.
    Licensed residential and commercial plumber

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    DIY Junior Member jono604's Avatar
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    Thanks for the feedback everyone.

    This all makes sense. I just wanted to be thorough and understand everything before I slap drywall up.

    The oven (wall mounted) and cooktop are in different areas so it didn't make sense to have them on the same circuit even if that was allowed.

    And to "jwelectric" I guess you're right. I probably do have a screw loose. Not only am I renovating the kitchen, I'm renovating the whole house... as hj and dlarrivee can attest to from my plumbing questions in the other forum.
    fun fun fun ...

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    DIY scratch-pad engineer leejosepho's Avatar
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    Quote Originally Posted by hj View Post
    Leejoseph; If that is a "hybrid" range, then the 120 control circuit for the cooktop is coming from the 240/120 electric supply. Even electric ovens use 120 for their circuit boards.
    Yes, I understand, and I was just not sure whether the OP had the same or had separate oven and cooktop units. Either way, having a gas top means we can still cook something even while the power is out since our top only needs power for the igniters.
    "Great minds discuss ideas, average minds discuss events and small minds discuss people." --Eleanor Roosevelt

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