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Thread: 220.55 and 40A range circuit

  1. #61
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    Art.422.10 (A) Branch circuits for house cooking appliances shall be permitted to be in accordance with table 220.55

  2. #62
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    Dec 2004
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    Fort Collins, CO NEC: 2014
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    Thumbs up

    Nicely done! :cool:

  3. #63
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    Mar 2003
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    we primarily do remodels w/ design build. The first thing we throw at the builder/homeowner/investor is USE GAS!!! Hehe...
    Actually we are running into alot of duel fuel ranges with nameplate ratings of 50 Amp. Our AHJ requires 6/3 minimum feeder regardless of nameplate ratings and/or NEC. Of course you could put this behind 30a, 40a, & 50a OCPD's (and previously mentioned 20a zinsco's or FP's ) The point I would like to make is,
    before I bid new construction or remodel the builder/homeowner/investor is required to give me range (if electric) style/model number and/or nameplate ratings. If they cant or wont then I can easily prove he/she dosent know what he/she is doing. If for some reason I decide to accept them without this info (and they accept my bid w/attitude) then we foot note and initial the probable change order before it ever gets off the ground. Someone already stated "the NEC is minimum standards" and doing load calculations without knowing the loads all the while being responsible for undersizing feeders/breakers and services with the ramafications of property damage and potentially loss of human life, just isnt what I would define as professional or good busines.

  4. #64
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    Quote Originally Posted by twa
    Art.422.10 (A) Branch circuits for house cooking appliances shall be permitted to be in accordance with table 220.55
    In the '02 NEC, that's Table 220.19. We must not forget to read the notes: Notice that a range is apparently considered differently than a fixed-in-place appliance, but how would a drop-in range be considered?:
    4. Branch-Circuit Load. It shall be permissible to compute the branchcircuit load for one range in accordance with Table 220.19. The branch-circuit load for one wall-mounted oven or one countermounted cooking unit shall be the nameplate rating of the appliance.
    The branch-circuit load for a counter-mounted cooking unit and not more than two wall-mounted ovens, all supplied from a single branch circuit and located in the same room, shall be computed by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range.
    I guess a range is a range, and 40a is enough for up to a 16Kw range.
    Last edited by LarryFine; 01-01-07 at 11:08 PM.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  5. #65
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    Ca and Wa
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    Welcome twa,

    The section quote, I believe, is a good reference to [422.10] Branch-Circuit Ratings capable of carrying current at a safe operating level. Calculations are to be permitted to appliance demand factors (i.e.[220.55] calculations) in determining of the overall load...and does not qualify the conductor type, temp and sizing or the connection requirements based on the range NPR. JMO until there is a defined answer from a higher relegating source.
    Last edited by gndrod; 01-02-07 at 12:40 AM.
    rbj, Seattle...Safety is a Professional Courtesy.

  6. #66
    Join Date
    Jun 2006
    Location
    The "Live Free or Die" State
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    Quote Originally Posted by gndrod
    Welcome twa,

    The section quote, I believe, is a good reference to [422.10] Branch-Circuit Ratings capable of carrying current at a safe operating level. Calculations are to be permitted to appliance demand factors (i.e.[220.55] calculations) in determining of the overall load...and does not qualify the conductor type, temp and sizing or the connection requirements based on the range NPR. JMO until there is a defined answer from a higher relegating source.
    I confess to not being able to understand what you are trying to say.

    Are you trying to say that 422.10 (when taken with 220.55) may not really mean what it appears to say? Are you suggesting that maybe there is some other meaning than that branch circuit loads calculated per 220.55 can be used as the basis for selecting conductors and OCPDs for branch circuits that serve single ranges?

    And what is "a higher relegating source"? And to whom would the higher relegating source be relegating and what would they be relegating?

  7. #67
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    There are many places in the NEC where de-rating is permitted. Remember that the NEC is concerned with only one thing, and that is safety. Re-read article 90. Adherence to the NEC will result in a SAFE installation, not one that is "convenient" or even "adequate". If a 16 KW range is installed on a 40-amp circuit would it be possible to overload the circuit? Yes. It is also possible to overload a service where the 4-or-more seperately controlled heaters are calculated at 40%. But it is not likely. If the circuit is overloaded, what happens? The overcurrent device opens the circuit, thus keeping the installation SAFE, which is the only NEC concern. If you feel that the customer would be better served by installing a larger circuit, you are free to do so, just as you are free to install more than two small appliance circuits and more than one 20-amp circuit to supply bathroom receptacles. Don't confuse good installation design with NEC requirements, they are two very different things. The only place that you MUST use a permitted derating is on an exam, otherwise it is available if you decide to use it, just as you are free to ignore it. 220.55 says what it says. It allows us to derate a range due to the fact that it would be extremely rare for all of the elements to be energized to their full capacity at one time. In the rare event that this would happen, there is an overcurrent device to protect the circuit. Safety is maintained. Some things cannot be controlled. We cannot prevent someone from utilizing all of the elements on a stove at one time, just as we cannot prevent a user from plugging in too many things on a receptacle circuit; that is why we have overcurrent devices. If we could control the load that is placed on a given circuit, the overcurrent device would provide only ground fault and short circuit protection (as in a motor circuit) and could be set at many times the ampacity of the conductors.

  8. #68
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    Quote Originally Posted by haskindm
    It allows us to derate a range due to the fact that it would be extremely rare for all of the elements to be energized to their full capacity at one time. In the rare event that this would happen, there is an overcurrent device to protect the circuit. Safety is maintained. Some things cannot be controlled. We cannot prevent someone from utilizing all of the elements on a stove at one time, just as we cannot prevent a user from plugging in too many things on a receptacle circuit; that is why we have overcurrent devices.
    The same thing applies to the question we often hear asking why it's permissable for branch-circuit breaker ratings to total higher than the main breaker.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  9. #69
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    The "Live Free or Die" State
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    Range Branch Circuits per NEC 220.55

    Following is a statement of the proposition and a list of citations that support the conclusion that Table 220.55 is permitted to be used for sizing branch circuits for ranges and cooking appliances.

    It has been a week since the last post on this subject, and a suggestion by one member that he would seek some clarification from the NFPA has not resulted in any rebuttal of the proposition from that source.

    The Proposition:
    It is permitted to use NEC 2005 Article 220.55 and Table 220.55 for sizing branch circuit conductors and overcurrent protection for individual ranges and for equivalent combinations of cooktops and ovens.

    Citations (From 2005 NEC unless otherwise noted):

    422.10(A) Individual Circuits. (Last paragraph) Branch circuits for household cooking appliances shall be permitted to be in accordance with Table 220.55

    Article 220 Branch-Circuit, Feeder, and Service Calculations

    Part II. Branch Circuit Load Calculations
    220.10 General. Branch-circuit loads shall be calculated as shown in 220.12, 220.14, and 220.16.

    220.14(B) Electric Dryers and Household Electric Cooking Appliances. Load calculations shall be permitted as specified in . . . 220.55 for electric ranges and other cooking appliances.

    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 1 3/4 kW shall be permitted to be calculated in accordance with Table 220.55. . . .

    Table 220.55 Demand Factors and Loads for Household Electric Ranges, . . .
    Note 4. Branch Circuit Load. It shall be permissible to calculate the branch-circuit load for one range in accordance with Table 220.55. . . .

    Conclusion:
    Numerous citations in NEC 2005 explicitly support the proposition that the load for an individual range or cooking appliance, and therefore the conductors and overcurrent protection, are permitted to be based on the Demand Factors and Loads of Table 220.55.

    Absent any contrary ruling from the NFPA, I believe the proposition stands.
    Last edited by Bob NH; 01-10-07 at 12:26 AM.

  10. #70
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    Bob, since we're still on the '02 NEC, what would be the equivalent table, 220.19?
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

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