220.55 and 40A range circuit

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Bob NH said:
I suggest that you, as a self-described author using the English language, might want to take your Webster's off the shelf and look up "relegate". Then tell me who is relegating what to whom or to where.
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Used relegate in the context of consign....Banish is the other option. I use MS Word's dictionary...a lot quicker. Bill Gates can't be misleading me now...Or would he?

Answer the question about wiring a B-C using #8 conductors for a 16kW range. Would you do this for your house?
 
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gndrod said:
Used relegate in the context of consign....Banish is the other option. I use MS Word's dictionary...a lot quicker. Bill Gates can't be misleading me now...Or would he?

Answer the question about wiring a B-C using #8 conductors for a 16kW range. Would you do this for your house?
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I used #6 copper with 50 amp breakers when I built my house in 1964, with separate 50 Amp circuits for cooktop and oven. They are both way overdesigned.

But that isn't the point. The discussion is about the code requirement.

The code clearly permits the use of Table 220.55 to establish branch circuit loads for the purpose of selecting conductors and overcurrent protection. That is the issue. What I would use, or what you or anyone else would use beyond the code minimum is not relevant.
 
Bob NH,
I feel we are coming together on common ground here. I am glad you realize where the NEC is on safety standpoints in this discussion and why there is a need to make distinctions between 210 and 220.
I am only one of many on this forum who have pointed out the differences in calculation methods for branch circuit conductor ampacity and sizing. Using the Article 220 for calculation of Optional Methods does not allow using Table 220.55. This is the first step to understanding why 210 is needed. Is this in agreement with your interpretations so far?
 
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Yo George. Maybe he is...let the dialog go a little further. BTW how did you fare in the great Colorado storm? Horses ok? Computers working...Oh and the family ok too?
 
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gndrod said:
Bob NH,
I feel we are coming together on common ground here. I am glad you realize where the NEC is on safety standpoints in this discussion and why there is a need to make distinctions between 210 and 220.
I am only one of many on this forum who have pointed out the differences in calculation methods for branch circuit conductor ampacity and sizing. Using the Article 220 for calculation of Optional Methods does not allow using Table 220.55. This is the first step to understanding why 210 is needed. Is this in agreement with your interpretations so far?
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Article 210 is needed. It says that the conductors shall have an ampacity not less than the maximum load to be served.

Article 220 is also needed, relevant, and not superseded by Article 210. It describes how to calculate the loads for which the conductors must be sized in accordance with the provisions of Article 210.

220 Branch-Circuit, Feeder, and Service Calculations
220.1 Scope. This article provides requirements for calculating branch-circuit, feeder, and service loads.

The concept is quite simple. Article 210 says design the conductors for the loads. Article 220 specifies the permitted methods for calculating the loads.

I repeat below the logic from an earlier post. I have seen nothing to suggest that it is not valid.

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):

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 to be determined in accordance with other sections of the code, 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.
 
Bob NH,
Citing only part of a section leaves out the total interpretation of those segmented quotes as is the example I posted (#80) for 422.10, which disallows using 220.55 for appliances needing BC's capable of carrying appliance current without overheating under the conditions specified. So rule out 220.55 from being used in 422 under wiring "conditions specified" circumstances. This goes back to 210.19 for proper load being served calculations.
220.82(B)(3) is also left out of your list that also eliminates the use of 220.55.
Can you elucidate further on these for starters?
 
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gndrod said:
Bob NH,
Citing only part of a section leaves out the total interpretation of those segmented quotes as is the example I posted (#80) for 422.10, which disallows using 220.55 for appliances needing BC's capable of carrying appliance current without overheating under the conditions specified. So rule out 220.55 from being used in 422 under wiring "conditions specified" circumstances. This goes back to 210.19 for proper load being served calculations.
220.82(B)(3) is also left out of your list that also eliminates the use of 220.55.
Can you elucidate further on these for starters?
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gndrod:
You are being absurd about this. The parts omitted in the segmented quotes are irrelevent and you know that. I have put the whole parts in below, with the originally omitted part in red, so that others can clearly see just how far you are stretching to try to make a point.

220.14(B) Electric Dryers and Household Electric Cooking Appliances. Load calculations shall be permitted as specified in 220.54 for electric dryers and 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. 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 number connected between any two phases.

422.10 Branch Circuit Rating. This section specifies the ratings of branch circuits capable of carrying appliance current without overheating under the condition specified.

(A) Individual Circuits. The rating of an individual circuit shall not be less than the marked rating of an appliance having combined loads as provided in 422.62. (Note by Bob NH: 422.62 refers to appliances consisting of motors and other loads and is not relevant to ranges.)

The rating of an individual branch circuit for motor-operated appliances not having a marked rating shall be in accordance with Part II of Article 430. Note by Bob NH: Doesn't apply because ranges are not motor-operated appliances.

The branch-circuit rating for an appliance that is continuously loaded, other than a motor-operated appliance, shall not be less than 125 percent of the marked rating, or not less than 100 percent of the marked rating if the branch-circuit device and its assembly are listed for continuous loading at 100 percent of its rating. Note by Bob NH: Doesn't apply because ranges are not continuously loaded.

Branch circuits for household cooking appliances shall be permitted to be in accordance with Table 220.55.
Note by Bob NH: And after all of the foregoing in 422.10, the writers of the code very clearly and explicitly permit Table 220.55 to be used to as the basis for branch circuits for ranges. The omitted parts don't apply to ranges.

END OF 422.10

gndrod says: 220.82(B)(3) is also left out of your list that also eliminates the use of 220.55.

220.82(B)(3) is left out of the list because it is totally irrelevant to calculating branch circuit loads. It was left out because 220.82(B) is part of Article 220, Part IV. Optional Feeder and Service Load Calculations, which allows feeders to be based on 100 percent of the first 10 kVa plus 40 percent of the remaining kVa. That section has nothing to do with determining branch circuit loads.

I'm sure that there are many more irrelevant sections of the code that could be cited in defense of an indefensible position. How long is the list?
 
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Range 101

Range 101

Bob NH said:
gndrod:
You are being absurd about this.
I'm sure that there are many more irrelevant sections of the code that could be cited in defense of an indefensible position. How long is the list?
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It amazes me to see a couple of intelligent people debating a point begin to melt-down and start the mudslinging. None of that bolsters either argument and is a turnoff (for me anyway). Both of you have made some good points - I happen to agree with NH - but some common decency and respect would benefit the whole debate. This is what I hate about many political campaigns, the debate gets lost in the gutter.
 
Every new house I've seen in King County (although none were in the city limits of Seattle) all have #8 wire on a 40A breaker for electric ranges. I doubt the electrician knows what size of range is going to be installed, but I've seen many at the big box stores that are in the 12.5 KW to 14 KW range.

None of those could be used on a 40A circuit if you had to size to a load that was the nameplate value. I doubt there are many call backs for tripping range breakers in these houses. If there were, that would be the first clue that the code should not be modifying the load for ranges.

The reason the optional method calculation uses ranges and dryers at full nameplate value is because a 40% factor is later applied. In the Standard method, the 35% or the 75% modifiers can not be applied to ranges or dryers.
 
RBJ, it can be a cathartic experience - I used to almost pop blood vessels in discussions with Mike Whitt, but soldiering forward while trying not to take a shot at the other guy exposed some interesting perspectives. In the long run, those discussions also settled me down quite a bit too. :D

I'd feel criminal for depriving you two of that experience. ;)

Besides, there's still a chance you'll be persuaded. :cool:
 
suemarkp said:
Every new house I've seen in King County (although none were in the city limits of Seattle) all have #8 wire on a 40A breaker for electric ranges.....
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Umm .... would that be a #8 copper, or aluminum wire there? :grin:
 
Copper, but aluminum would be OK too as long as it isn't NM cable (every range receptacle I've seen of recent manufacture has a 75C stamp on it). Don't see aluminum used much here except for service drops and service laterals. But perhaps that has changed in the last few years with the absurd prices of copper.
 
I haven't seen this mentioned yet
210.21 (B) 4
(Why)Would the NEC specifically allow the range receptacle to be rated as per 220.55 but not the branch circuit conductors?
 
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