220.55 and 40A range circuit

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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
 
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.
 
twa said:
Art.422.10 (A) Branch circuits for house cooking appliances shall be permitted to be in accordance with table 220.55
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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.
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I guess a range is a range, and 40a is enough for up to a 16Kw range.
 
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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.
 
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gndrod said:
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.
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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?
 
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.
 
haskindm said:
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.
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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.
 
Range Branch Circuits per NEC 220.55

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.
 
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gndrod said:
Be patient Bob NH. Response from any large organization is like waiting for Congress to get back in session. :)
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:D So, you're saying that if I select DELETE it just happens very slowly ?
 
Home on the range...220.55

Home on the range...220.55

al hildenbrand said:
:D So, you're saying that if I select DELETE it just happens very slowly ?
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There must be a slower delete key then the one you mention. The key staff engineer is on vacation according to my spies in Quincy....They were not aware of my earlier Emails until I called today....:)

Bob NH,
I am still working on your proposition. In the mean time, peruse Art. 210.2 and the qualifying accordances or lack thereof in Table 210. Table 220.55 and related note 4 is not listed in the table 210 for other article amended provision usage as a supplement to 210. Any citations or propositions made earlier do not have exceptions that overule 210.19(A)(3) for application of 220.55 Demand Factor percentile 'derating'. Thanks for your patience.

sp
 
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gndrod said:
There must be a slower delete key then the one you mention. The key staff engineer is on vacation according to my spies in Quincy....They were not aware of my earlier Emails until I called today....:)

Bob NH,
I am still working on your proposition. In the mean time, peruse Art. 210.2 and the qualifying accordances or lack thereof in Table 210. Table 220.55 and related note 4 is not listed in the table 210 for other article amended provision usage as a supplement to 210. Any citations or propositions made earlier do not have exceptions that overule 210.19(A)(3) for application of 220.55 Demand Factor percentile 'derating'. Thanks for your patience.

sp
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I think you are avoiding the plain language of the code that explicitly permits the use of Table 220.55, including Note 4 thereof, as the basis for designing branch circuits for ranges. See my post of 01-09-2007 at 11:56 AM.

I challenge you to sent my post of 1-9-2007, and your post of today, and this reply, to the NFPA contact person in Quincy. Let us all see what the response is when BOTH SIDES of the discussion are presented.

210.2 Other articles for Specific-Purpose Branch Circuits. Branch circuits shall comply with this article and also with the applicable provisions of other articles of this Code. The provisions for branch circuits supplying equipment listed in Table 210.2 amemd or supplement the provisions in this article and shall apply to branch circuits referred to therein.

The fact that ranges are not mentioned in Table 210.2 is irrelevant. There are other articles in the Code that explicitly deal with appliances. The Code is not contradictory. If Artlcle 220 explicitly says that something is permitted, then it can not be then prohibited by some vague and unique interpretation of another article that doesn't mention the circuit provisions that are explicitly permitted in Article 220.

210.19(A)(3) doesn't have to be overruled by anything because it says that the circuit "shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served".

It is the "maximum load to be served" that is defined in Table 220.55.

We are not going to agree on this matter until you come to the realization that the LOAD referred to in 210.19(A)(3) is the LOAD that is calculated in accordance with the provisions of Table 220.55.

Nothing that you have raised here (1-17-2007) contradicts the code sections that I cited in my post of 01-09-2007, and the conclusions reached and stated in that post remain valid.

And I still have no idea what you were talking about in your post of 01-01-2007 when you mentioned "a defined answer from a higher relegating source". What is "a higher relegating source"? And to what or to whom would the higher relegating source be relegating and what would they be relegating? And what does relegating have to do with this issue?
 
JohnJ0906 said:
422.10(A) says (in part) "branch circuits for household cooking appliances shall be permitted to be in accordance with table 220.55"
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Johnjo906, Taking that sentence out of 422.10(A) of Part II. Installation leaves a lot of incomplete interpretation to "accordance with Table 220.55".

Let's not overlook the section heading as follows;
NEC 2005 "422.10 Branch-Circuit Rating. This section specifies the ratings of branch circuits capable of carrying appliance current without overheating under the conditions specified."
(When using 220.55, the condition is...an #8 awg Cu conductor, rated for 40A at 60 C [310.16] to a fully lit 16 kW range at a maximum load drawing 67 amps.)

Is this safe? Can you guarantee a client that the circuit conductor terminations will not overheat and last 40 years? Most of all, would you wire your house with this configuration?

Bob NH,
What is the reason why Article 210 was ever written if Table 220.55 is construed for conductor ampacity and sizing for the load being served?

Shame shame. Not once is "the maximum load to be served" mentioned in Table 220.55 and for that matter Article 220. You misquote the NEC.

According to 90.1(C) the NEC is not intended as a design manual for "propositions" of your own wording. At best, save those for cycle 2011.

422.10 Branch-Circuit Rating also states "The rating of an individual branch circuit shall not be less than the marked rating of the appliance or the marked rating of an appliance having combined loads as provided in 422.62."

What is the rating marked NPR of a 16 kW range? Go figure.

Then answer my question to you...Would you wire houses with #8 awg for 16 kW range circuits? BTW use AHJ as a relegating source.
I do not know everything, that is why I have a solid reference base and pay for a membership in the electrical section of the NFPA.

I do not waste my good time and membership fees for a discussion with you.
I challenge you to fork up your own hard-earned bucks for a membership in the NFPA. Read the CYA disclaimer ahead of Article 90 and you can see that everything is all about safety.
 
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