Range Wire Sizing

Status
Not open for further replies.

jwelectric

Senior Member
Location
North Carolina
iwire said:
jwelectric said:
I still say that the last sentence of 210.19(A)(3) means just what it states and this is that the minimum circuit for a range with a rating of 8 ? kw or more is 40 amps.

And again you are correct up until the range exceeds 40 amps.


jwelectric said:
This is confirmed my most manufactures of ranges.

Out of the links you posted I only found the KW of one.

It was 12.4 KW and required a 50 amp circuit.

Total Connected Load - kW @ 240V/208V: 12.4/9.5

ENERGY GUIDE
Wattage: 1240
AMPS: 50
Voltage: 240

Obviously it should show 12,400 watts.

http://www.ajmadison.com/cgi-bin/ajmadison/AER5845QA.html

Where do you see the "up to 40 amps" written? I can't find these words I only see "or more".

Click on the info & guides tab and go to page 5 for a little better detail on this installation.
:)
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Mike,
I see your point and the words in the NEC support your point. However where there are conflicting rules, and I think that is what we have in this section, I just choose to ignore the less stringent rule. It appears that CMP 2 agrees with me. Proposal 2-209 in the 95ROP suggested the following wording: "For ranges rated between 8 3/4 kW and 11.9 kW, the minimum branch circuit rating shall be 40 amperes. For ranges rated 12 kW and higher the minimum branch circuit rating shall be 50 amperes." The substantiation said that larger ranges need larger branch circuits. The proposal was rejected with a panel statement that said: This section still requires that the branch circuit conductors have a rating not less than the maximum load to be served". It appears that the last sentence in this section has no use, and it should have been removed by the CMP in response to this proposal.
Don
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Mike, first of all, it's obvious that the code says what you say it says, and we're disagreeing with you on what it means. You're saying that "a minimum of 40 amps" implies that it never needs to be any higher. That's why we're saying that you're implying that the "minimum" is also the "maximum" ever required.

Obviously, that's not correct. It almost looks like that 8-3/4kW sentence is redundant at best, or should be dropped at worst. Why is it there? What is unique about that rating? Does it coincide with some other characteristic difference, such as physical size? Maybe lower wattages are (or were) always smaller, less than 30" wide?

Maybe it means that lower-wattage ranges are smaller, like efficiency-apartment types, and it's likely that a range 8-3/4kW or larger is full size, and could easily be replaced with another one, and that's likely to require 40 amps, even if the present one could squeak by on 30. That's what should be investigated further.

In any case, you must be aware that you can't say that a range circuit need never be greater than 40 amps, with no exception.

Kumbaya!
 

jwelectric

Senior Member
Location
North Carolina
don_resqcapt19 said:
Mike,
I see your point and the words in the NEC support your point. However where there are conflicting rules, and I think that is what we have in this section, I just choose to ignore the less stringent rule. It appears that CMP 2 agrees with me. Proposal 2-209 in the 95ROP suggested the following wording: "For ranges rated between 8 3/4 kW and 11.9 kW, the minimum branch circuit rating shall be 40 amperes. For ranges rated 12 kW and higher the minimum branch circuit rating shall be 50 amperes." The substantiation said that larger ranges need larger branch circuits. The proposal was rejected with a panel statement that said: This section still requires that the branch circuit conductors have a rating not less than the maximum load to be served". It appears that the last sentence in this section has no use, and it should have been removed by the CMP in response to this proposal.
Don

I agree with you Don it should have been removed but it wasn't and therefore it is still there. As long as it is there it will give fuel to at least one person that will argue that a minimum 40 amp circuit is all that is required for any size range.

Let?s hope that it is readdressed.
 

jwelectric

Senior Member
Location
North Carolina
LarryFine said:
.
In any case, you must be aware that you can't say that a range circuit need never be greater than 40 amps, with no exception.

Kumbaya!

And why not? This is exactly what the last sentence of 210.19(A)(3) states
 

iwire

Moderator
Staff member
Location
Massachusetts
jwelectric said:
iwire said:
Out of the links you posted I only found the KW of one.

It was 12.4 KW and required a 50 amp circuit.

Total Connected Load - kW @ 240V/208V: 12.4/9.5

ENERGY GUIDE
Wattage: 1240
AMPS: 50
Voltage: 240

Obviously it should show 12,400 watts.

http://www.ajmadison.com/cgi-bin/ajmadison/AER5845QA.html

Click on the info & guides tab and go to page 5 for a little better detail on this installation.
:)

Mike I went to the specification page from the link you supplied which said 50 amps.

The page you would like me to look at has only to do with the cord not the circuit.

Again the specification page requires a 50 amp circuit

Give it up even the CMP does not agree with you. :lol:

The proposal was rejected with a panel statement that said: This section still requires that the branch circuit conductors have a rating not less than the maximum load to be served".
 

amptech

Senior Member
Location
Indiana
I tried to post a link to the Maytag electrical installation instructions with no luck. It is a pdf file that opens in Adobe and I must not be doing it right. Just go to maytag.com and look up wall ovens-electric and click on manuals. It clearly states that the values in their table are minimum circuit requirements. If you installed a 40A circuit for a 10kw Maytag wall oven you would be in violation of the manufacturers instructions.
 

jwelectric

Senior Member
Location
North Carolina
amptech said:
I tried to post a link to the Maytag electrical installation instructions with no luck. It is a pdf file that opens in Adobe and I must not be doing it right. Just go to maytag.com and look up wall ovens-electric and click on manuals. It clearly states that the values in their table are minimum circuit requirements. If you installed a 40A circuit for a 10kw Maytag wall oven you would be in violation of the manufacturers instructions.

Here is the link that take you stright to the manual

http://www.maytag.com/cust_serv/pdf_installation_manual/doubleovenrangeinstall.pdf
 

jeff43222

Senior Member
OK, now that further discussion has everyone on the same page... :D

Is there such a thing as a 60A range receptacle? I've never seen one. Or a 60A range cord? 210.21(B)(3) says that if I install a 60A circuit, I have to install a 60A receptacle.

Does anyone have a problem with me installing 6-3 copper and using a 50A breaker, cord, and receptacle?
 

Gmack

Banned
Location
Michigan
Mike jw,

My choice of "word" was not meant for an insult. Poor choice on my part.

Someone else mentioned that you teach and I meant/questioned your "judgment" here as to what might/could happen as a result of your reasoning.

You mentioned later that wou would "pass" for inspection a 27kW range setup, on a 40A

That is not safe. I dont care what you read into or out of your sentence.

Passing a branch circuit that could run at its maximum or near to it, for
extended periods would not be a safe. I shouldnt have to explain.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Gmack,
You mentioned later that wou would "pass" for inspection a 27kW range setup, on a 40A
That is not safe. I dont care what you read into or out of your sentence.
Passing a branch circuit that could run at its maximum or near to it, for
extended periods would not be a safe.

How is it not safe? The circuit is designed for 40 amps and continuous operation at its rating is not a safety issue. Now, I would agree that it may not be a good idea, because under some conditions the load will exceed 40 amps and the breaker will trip, but I don't see that as a safety issue.
Don
 

Gmack

Banned
Location
Michigan
Don, A 27kw range could easily draw at or near max 40A.

Its hard on equipment doing things that way, which lead to over heating?

Then other things happen.
 

paul32

Senior Member
Location
Minnesota
I will attempt to explain that "last sentance" for both Mike and Don. Mike thinks it overrides everything and Don thinks it doesn't do anything. Both are wrong.

jwelectric said:
See no one has yet addressed the last sentence of 210.19(A)(3).
I have heard a lot of opinion but as yet not one word as to the last sentence of this section.
Either you can or you can?t explain these words and if you can?t then I stand on what I have been saying all along.

The words are as clear as day that this is addressing the minimum circuit size as the entire Article of 210 does.

ARTICLE 210 Branch Circuits
I. General Provisions
210.1 Scope.
This article covers branch circuits except for branch circuits that supply only motor loads, which are covered in Article 430. Provisions of this article and Article 430 apply to branch circuits with combination loads.
II. Branch-Circuit Ratings
210.19 Conductors ? Minimum Ampacity and Size.
(A)(3) (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 8? kW or more rating, the minimum branch-circuit rating shall be 40 amperes.

If the last sentance was deleted, we would have that the conductor needs to be large enough for the load. Adding that sentance does not change the previous ones. It simply says, if the load of the range is under 40A, you still need to have a 40A circuit. That is what a MINIMUM is. I assume the reason for that is in the future you might get a larger range.

Take the 8.75kW range. The load could be (using the 220 demand factors) 8kW /240V = 33.3A, or a 35A circuit. This extra sentance says it needs to be 40A instead. Don, it does serve a purpose. Mike, it does not say 40A for everything.
 

amptech

Senior Member
Location
Indiana
I think Paul has nailed it down! That is exactly how I interpret the article and both my county and city inspectors agree. They both said they would fail an installation of a 40A branch circuit for a 10kw double wall oven(that's the example I gave them) based on the wording of 210.19(A)(3)"...and other 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."
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Gmack,
Its hard on equipment doing things that way, which lead to over heating?
No...equipment operating at its designed maximum should not overheat. Only currents above the rating will cause the equipment to overheat. When the range draws more than 40A, the breaker will act to open the circuit based on the current and the trip curve. The purpose of the OCPD is to prevent overheating.
Don
 

Gmack

Banned
Location
Michigan
It is clear that the NEC would rather we dont "load" our equipment/conductors at 100% or near that either.

210.19 Conductors ? Minimum Ampacity and Size
(A) Branch Circuits Not More Than 600 Volts
(1) General Branch-circuit conductors shall have an ampacity not less than the maximum load to be served. Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch-circuit conductor size, before the application of any adjustment or correction factors, shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load.

Exception: Where the assembly, including the overcurrent devices protecting the branch circuit(s), is listed for operation at 100 percent of its rating, the allowable ampacity of the branch circuit conductors shall be permitted to be not less than the sum of the continuous load plus the noncontinuous load.

Conductors of branch circuits rated not more than 600 volts must be able to supply power to loads without overheating. The requirements in 210.19(A)(1) establish minimum size and ampacity requirements to allow that to happen. The requirements for the minimum size of overcurrent protection devices are found in 210.20. An example showing these minimum-size calculations is found in the commentary following 210.20(A), Exception.

We as electricians never run equipment at "maximum". No electrician would design a such circuit.

Adjustments must be made [NEC] to 80% for continuous loads. Just one example.

.
 

iwire

Moderator
Staff member
Location
Massachusetts
Gmack said:
We as electricians never run equipment at "maximum". No electrician would design a such circuit.

Gmack you have to speak for yourself. :)

I have no problem running a non-continuous load at 100% depending on the application.

The NEC allows it and it is not unsafe, I do agree it is not usally the best design.

It is not 'hard' on the equipment assuming the rules of the NEC have been followed.
 

jwelectric

Senior Member
Location
North Carolina
Now that we have danced all around for seven pages and ninety six posts and no one has yet explained the last sentence of 210.19(A)(3) although I thought that Don was going to for a couple of minutes, I will be glad to explain it for you.

I will show just how easy the NEC is to understand and just how easy it is to get hung up on something other than the question at hand.

Before I get to 210.19(A)(3) let me go to a couple of other sections on the NEC that have been posted in this thread.

First I will address section 220.55.
Just what is being addressed in 220?
Article 220 addresses Branch-Circuit, Feeder, and Service Calculations or the sizing of the conductors for the Branch-Circuit, Feeder, and Services.
In 220.1 we are told how Article 220 is laid out and what order the Branch-Circuit, Feeders, and Service calculations are made.
I. General
220.1 Scope.
This article provides requirements for calculating branch-circuit, feeder, and service loads. Part I provides for general requirements for calculation methods. Part II provides calculation methods for branch circuit loads. Parts III and IV provide calculation methods for feeders and services. Part V provides calculation methods for farms.
In Part II of 220 (Branch-Circuit) section 220.14(C) we are told that we can use Table 220.55 to size the conductors for a range.
In Part III of 220 (Feeders and Services) we find Table 220.55 and the guidelines for sizing the conductors for a range or for multiple ranges.

Now that I have covered the proper way to size the conductors for a range, have I covered 210.19(A)(3) or negated the last sentence of that section? NO
None of this has any bearing on the last sentence which states ranges of 8? kW or more rating, the minimum branch-circuit rating shall be 40 amperes. This sentence still is part of the NEC and means just what it is saying.
I have not addressed the conductors of the branch circuit in any way with my post other than when I was addressing 220.55. I may have implied the conductors by saying ?circuit? and I will admit that I was using the term out of context of 210.19(A)(3) but it was unintentional.

For us to understand just what is being said in 210.19(A)(3) we must first know what is being addressed. The last sentence of that section is only addressing the rating of the circuit not the conductors.
What determines the rating of a circuit?
The answer of this question can be found in 210.3
210.3 Rating.
Branch circuits recognized by this article shall be rated in accordance with the maximum permitted ampere rating or setting of the overcurrent device. The rating for other than individual branch circuits shall be 15, 20, 30, 40, and 50 amperes. Where conductors of higher ampacity are used for any reason, the ampere rating or setting of the specified overcurrent device shall determine the circuit rating.

Upon careful reading of this section of the code I learn that the overcurrent device is what determines the rating of the branch circuit NOT THE CONDUCTORS.
Now as I have said all along the minimum circuit rating for a range 8 ? kw and everyone more than 8 ? kw is 40 amperes.
:)
Let's not forget what is being addressed. It is the rating not the size of the conductors.
I have said that I think that the last sentence should be removed and now each of you know why it wasn't.
:)
 

iwire

Moderator
Staff member
Location
Massachusetts
jwelectric said:
Now that we have danced all around for seven pages and ninety six posts and no one has yet explained the last sentence of 210.19(A)(3) although I thought that Don was going to for a couple of minutes, I will be glad to explain it for you

Mike I like you but I have to think you are truly out of your mind. :lol:

WE ALL HAVE EXPLAINED IT TO YOU! :lol: :lol:

Don showed us what the Code Making Panel thought of that section. 8)

The proposal was rejected with a panel statement that said: "This section still requires that the branch circuit conductors have a rating not less than the maximum load to be served".

Now your just blowin wind. :lol:

You will now tell us how the NEC requires the conductors to be large enough for the load served but the breaker can still be a 40. :roll:

Bob
 

jwelectric

Senior Member
Location
North Carolina
iwire said:
Mike I like you but I have to think you are truly out of your mind. :lol:

WE ALL HAVE EXPLAINED IT TO YOU! :lol: :lol:

No you all explained everything but why this section was still in the code book and what it meant.

iwire said:
Don showed us what the Code Making Panel thought of that section. 8)

The proposal was rejected with a panel statement that said: "This section still requires that the branch circuit conductors have a rating not less than the maximum load to be served".

Now your just blowin wind. :lol:

No Don covered the part about the conductors but said nothing about the rating of the circuit.
So I did as you ask and sought an answer from someone other than this forum.

iwire said:
You will now tell us how the NEC requires the conductors to be large enough for the load served but the breaker can still be a 40. :roll:

Bob

Okay here it goes. This is an e-mail to the Department of Insurance
Question to DOI
Could the last sentence of this section be used to install any range rated more than 8?kW?

Would it be permissible to install a 18kW range on a minimum 40 amp circuit.

Answer from DOI
NO! Could you install a 40 opcd on an 18KW range? Yes if the conductors are rated for the 18KW range.
Look at 220.55 and Table 220.55 note 1
Thanks

The rest came from a telephone conversation and is almost word for word the way it was explained to me.
At least I found someone that would address the last sentence of 210.19(A)(3) and nothing else something I couldn't get in here.
:)
 
Status
Not open for further replies.
Top