Building Code and Building Construction - Questions and Answers
Or when you want to know how construction is supposed to be done.

|
AskCodeMan.com
|
The following Codemen are available to answer your questions:
All Codes and Standards - Jerry Peck, Codeman


Q&A Board links
  • REGISTER

  • FAQ

  • LOGIN

  • Q&A BOARD INDEX

  • View New Questions

  • View Unanswered Questions

  • View Active Questions/Answers

  • Mark Questions as read

  • View Your Questions

  • Go To Your User Control Panel




  • Links to:
  • Construction Litigation Consultants


  • Florida Building Commission

  • Florida Building Codes Online


  • International Code Council

  • ICC Codes Free Online


  • Building Officials and Administrators of Florida




  • Product Approvals
  • Florida Product Approval

  • ICC Evaluation Reports Search

  • Miami-Dade NOA Search




  • Inspector and Contractor License Search
  • Search Florida Licenses




  • Technical links
  • Technical Information page


























































  • Contact Codeman



  • Custom Search

    electrical residential ranges/ovens

    electrical residential ranges/ovens

    New postby Dryden on Thu Jan 03, 2013 10:29 pm

    Jerry, Thanks for sharing your insightful knowledge with us. Once again, I'm eager to review your answer to my simple question.
    A free standing electric range, 240 volt, 11.4kw, 4 wire, with 50ft distance from the panel.
    Whats the size of breaker and conductors for this branch circuit?
    NEC 2011
    210.19 (a)(3)
    220.14 (b)
    220.55 w/notes

    11400/240=47.5amp
    50amp ocpd w/ #6awg nmb
    Does the 1.25 continous load apply?
    47.5x1.25=59.375amp
    60amp or ocpd w/ #6awg nmb
    or Table 220.55 col c 8kw
    8000/240=33.33
    40amp ocpd w/ #8awg nmb
    33.33x1.25=41.66
    40 or 50amp ocpd w/ #8awg nmb
    or something else?
    do not have manufacturers listings (sorry)

    Muddy Waters
    Dryden
     
    Posts: 3
    Joined: Sun Apr 22, 2012 11:01 pm

    Re: electrical residential ranges/ovens

    New postby Jerry Peck - Codeman on Thu Jan 03, 2013 10:49 pm

    Dryden wrote:do not have manufacturers listings


    Do you know the manufacturer? The model number? Style/size?

    The manufacturer requirements could likely be found on the internet from the manufacturer's web site, especially with a model number or style, sometimes the photos on their web sites show the one you saw.

    Just checking as that could factor into the answer.
    Jerry Peck - CodeMan
    AskCodeMan.com

    Construction and Litigation Consultant
    Construction Litigation Consultants, LLC.
    ConstructionLitigationConsultants.com
    User avatar
    Jerry Peck - Codeman
    Site Admin
     
    Posts: 1088
    Joined: Fri Dec 12, 2008 12:06 pm

    Re: electrical residential ranges/ovens

    New postby Jerry Peck - Codeman on Sat Jan 05, 2013 6:13 pm

    Lacking specific information on the range, let's go through it section by section, keeping in mind that the nameplate ratings may alter the answer and the outcome.
    Dryden wrote:A free standing electric range, 240 volt, 11.4kw, 4 wire, with 50ft distance from the panel.
    Whats the size of breaker and conductors for this branch circuit?
    NEC 2011
    210.19 (a)(3)
    220.14 (b)
    220.55 w/notes


    11.4 kW electric range

    NEC 2011
    - 210.19 (a)(3)
    - 210.19 Conductors — Minimum Ampacity and Size.
    - - (A) Branch Circuits Not More Than 600 Volts.
    - - - (3) Household Ranges and Cooking Appliances. Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 8¾ kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
    - - - - Exception No. 1: Conductors tapped from a 50-ampere branch circuit supplying electric ranges, wall-mounted electric ovens, and counter-mounted electric cooking units shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branch-circuit conductors. The taps shall not be longer than necessary for servicing the appliance.
    - - - - Exception No. 2: The neutral conductor of a 3-wire branch circuit supplying a household electric range, a wall-mounted oven, or a counter-mounted cooking unit shall be permitted to be smaller than the ungrounded conductors where the maximum demand of a range of 8¾-kW or more rating has been calculated according to Column C of Table 220.55, but such conductor shall have an ampacity of not less than 70 percent of the branch-circuit rating and shall not be smaller than 10 AWG.

    Exceptions 1 and 2 do not apply, which leaves us with:
    - Household Ranges and Cooking Appliances. Branch-circuit conductors supplying household ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. For ranges of 8¾ kW or more rating, the minimum branch-circuit rating shall be 40 amperes.

    The 11.4 kW rating of the appliance meets the "of 8¾ kW or more rating" part, and thus "the minimum branch-circuit rating shall be 40 amperes", which is not the same as stating 'the branch-circuit rating shall be 40 amps'

    11.4 kW / 240 volts = 47.5 amps, which is too much for a 40 amp rated circuit. Based on 47.5 amps, the minimum branch-circuit overcurrent protection rating could be 50 amps (next higher standard rating)

    220.14 (b)
    - 220.14 Other Loads — All Occupancies.
    - - In all occupancies, the minimum load for each outlet for general-use receptacles and outlets not used for general illumination shall not be less than that calculated in 220.14(A) through (L), the loads shown being based on nominal branch-circuit voltages.
    - - - Exception: The loads of outlets serving switchboards and switching frames in telephone exchanges shall be waived from the calculations.
    - - - (B) Electric Dryers and Household Electric Cooking Appliances. Load calculations shall be permitted as specified in 220.54 for electric dryers and in 220.55 for electric ranges and other cooking appliances.

    All this does is direct us to 220.55 (with the notes).

    220.55 w/notes
    - 220.55 Electric Ranges and Other Cooking Appliances — Dwelling Unit(s).
    - - The load for household electric ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliances individually rated in excess of 1¾ kW shall be permitted to be calculated in accordance with Table 220.55. Kilovolt-amperes (kVA) shall be considered equivalent to kilowatts (kW) for loads calculated under this section.
    - - Where two or more single-phase ranges are supplied by a 3-phase, 4-wire feeder or service, the total load shall be calculated on the basis of twice the maximum number connected between any two phases.

    Note that this says (bold and underlining are mine) "shall be permitted to be calculated in accordance with Table 220.55", this does not state that it 'shall be calculated' in accordance with blah, blah, blah.

    Table 220.55 says that the load is "permitted" to be calculated as a maximum demand of 8 kW provided the notes are addressed.
    - Note 1 does not apply as Note 1 is for "over 12 kW"
    - Note 2 does not apply as Note 2 is for averaging out multiple appliances and there is only one appliance
    - Note 3 does not apply as Note 3 is for ranges "1¾ through 8¾" and this appliance is greater than 8¾ kW
    - Note 4 does apply and says that is shall be "permissible" to calculate the branch-circuit load for one range in accordance with Table 220.55. The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance. Note 4 goes on regarding more than one appliance, but there is only one appliance here.
    - Note 5 does not apply as this is not used for instructional programs (at least you did not say it was, and if it was, all Note 5 says is that it is permissible to use this table for that use).

    Thus the only note which is applicable is Note 4 and the first two options, depending on which is being referenced:
    - It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55.
    - - Being as you said "A free standing electric range" I will presume that this is the option which applies, not the second option.
    - The branch-circuit load for one wall-mounted oven or one counter-mounted cooking unit shall be the nameplate rating of the appliance.
    - - I am presuming that this second option does not apply, see first option answer.

    "It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55."
    You don't have to use that, but you can, and if you choose to, then you could apply a rating of 8 kW to that 11.4 kW range.

    8 kW / 240 volts = 33.33 amps, which could be on a 35 amp breaker, except that 210.19(A)(3) says the minimum rating "For ranges of 8¾ kW or more rating" shall be "40 amperes".

    The answer, then is two-fold:
    1) 50 amp overcurrent protection rating and 50 amp conductor rating.
    2) However, it is "permitted" to have a 40 amp overcurrent protection rating and 40 amp conductor rating. This is because a "household" electric range is not going to be "on" for the number of hours that a commercial electric range would be on for (most household electric ranges, in most households, for most days).

    Not sure if that answers your question or not?
    Jerry Peck - CodeMan
    AskCodeMan.com

    Construction and Litigation Consultant
    Construction Litigation Consultants, LLC.
    ConstructionLitigationConsultants.com
    User avatar
    Jerry Peck - Codeman
    Site Admin
     
    Posts: 1088
    Joined: Fri Dec 12, 2008 12:06 pm

    Re: electrical residential ranges/ovens

    New postby Dryden on Sat Jan 05, 2013 11:33 pm

    Jerry,
    Yes Sir, that does answer my question. I was concerned, I might be "out smarting my common sense" there for a moment:)
    As always your eye for detail and professional explanations are greatly appreciated.
    Bouncing around through the NEC, UL white book, NFPA 70E, manufacturers instructions, and "the lot" can encroach into the "pin ball effect". Its a good peace of mind for me to have you around when the "simple" questions pop up:)
    If I am reading between the lines correctly, I am pressed to agree "permissible" isn't always the recommended. The unturned stone of the manufactures instructions may allow and/or recommend a 50amp OCPD. If so #6 awg nmb with the 50amp OCPD will be used.


    Thank You,

    Van
    Dryden
     
    Posts: 3
    Joined: Sun Apr 22, 2012 11:01 pm


    Return to Electrical: Service Equipment, electrical panels, wiring, lighting, switches, receptacles, etc.



    Who is online

    Users browsing this forum: No registered users and 1 guest



    www.AskCodeMan.com
    cron