Range Wire Sizing

[iwire]

Well George the way I figure it is that Table 220.55 goes all the way up to 61 ranges and over.

Mike we are not talking about 61 ranges we are talking about one particular range on a branch circuit.

 

[jwelectric]

Bob please accept my apology if you think that I was talking down to you. This is not what I was intending to do. I was only trying to point out where I found the wording for my statement after reading you post on page one

I can not for the life me comprehend why you see it as this;

For ranges of 8? kW or more rating, the maximum branch-circuit rating required shall be 40 amperes.

Mike I am not being a wise @8% I am truly lost as to you thoughts on this section.

First I don?t see this as a MAXIMUM I see it for what it says.

The first sentence of 210.19 seems to be throwing you thoughts off kilter just a little.
It is the second sentence that wraps the circuit for a single range and it clearly states that a minimum circuit of 40 amps for ranges 8 ? kw and larger. Now if I choose I could install a larger circuit but it is not required.

As I have seen some try to use the first sentence to mandate that 220.55 would not even apply I have come to the conclusion that the first sentence is mandating that the circuit conductors are required to be at least the size as the overcurrent device and 240.4(B) would not apply. This is just my opinion as what the first sentence is addressing.

 

[RUWired]

Mike , You will have to supply a larger circuit if the maximum (demand ) load is higher or the name plate rating is higher.
Rick

 

[George Stolz]

The first sentence of 210.19 seems to be throwing you thoughts off kilter just a little.

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.

Uh...why do you say that? Paraphrasing that sentence, it says the branch circuit conductors shall be as big or bigger than the breaker feeding them, and no less than the max the range can pull.

We are (at least I am) more than willing to call "the maximum load to be served" the demanded load we get from Table 220.55. That suits me fine. It's not perfectly logical, but 210.19 & 220.55 aren't really meshing together very well for either of our purposes.

For ranges of 8 3 /4 kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
This is a distinct and independent sentence. This is drawing a line and saying, "This is what we consider a substantial range. Do not supply a range of this size with anything less than 40 amps." There is no permission to throw the nameplate in the toilet and just use 40 amps for everything.

It is the second sentence that wraps the circuit for a single range and it clearly states that a minimum circuit of 40 amps for ranges 8 ? kw and larger.

Can you restate this statement more clearly? What are you trying to say?

Please address this statement, Mike, because I think it represents a fundamental flaw in your logic:

What is the point of going to the trouble of all that math, if you're always allowed to just install a 40A circuit and forget about it? You're not making any sense, think about it. What's the point of allowing us to calculate a branch circuit load according to a demand table, if we can overlook the results and just put in a minimum?

Edit to add: Bob, I tried plaid, but it didn't show too well.

 

[jwelectric]

I am not adding anything to the section in question nor am I taking anything away I am only quoting the last sentence in the section.

If it don?t mean what it says it means then using the sentence please give it your best shot and convince me of something different.
:?:

 

[George Stolz]

The way I read it is that I could install a 27kw range on a 40 amp circuit

Mike, you are adding something to that last sentence. You are changing the word "minimum" to maximum. There's no two ways about it.

Table 220.55 allows us to demand down the nameplate rating. It doesn't allow us to just disregard it and install a 40 amp circuit.

Your thinking is wrong. Setting a minimum does not entail a maximum. The minimum service size to a dwelling unit is 100 amps. Does that mean that if a load calc comes out to 195 amps, you can install a 100 amp service, because code says minimum is 100? Of course not.

But that's what you're saying, for a range.

 

[jwelectric]

The way I read it is that I could install a 27kw range on a 40 amp circuit

Mike, you are adding something to that last sentence. You are changing the word "minimum" to maximum. There's no two ways about it.

But that's what you're saying, for a range.

No that is not what I am saying at all.
That is what 210.19(A)(3) is saying in the last sentence as follows:

For ranges of 8? kW or more rating, (what size is it outlining?)
the minimum branch-circuit rating shall be 40 amperes. (what is the minimum size circuit required here?)

This is different that the minimum size service required in 230.79(C) in that 210.19(A)(3) gives the size limitation of the range. It says anything that is 8 3/4 kw and larger.

 

[iwire]

George I must say excellent posts (even without plaid :lol: )

Mike as pointed out your thinking is flawed on this.

I am literally dumbfounded how a man with your knowledge of the NEC thinks that minimum is also the maximum.

I will steal from George. :wink:

The minimum service size to a dwelling unit is 100 amps. Does that mean that if a load calc comes out to 195 amps, you can install a 100 amp service, because code says minimum is 100?

Mike's response to that

This is different that the minimum size service required in 230.79(C) in that 210.19(A)(3) gives the size limitation of the range. It says anything that is 8 3/4 kw and larger.

Mike if 230.79(C) was written like this;

For single family dwellings of 1,500 sq ft or more, the minimum service rating shall be 100 amperes.

You would believe that a 150,000 sq ft house could also be supplied with a 100 amp service?

Mike please look for some outside sources to confirm you thoughts as I truly believe you are of target and as you are an instructor you should want to pin this down for sure.

Stop bouncing around the NEC to the demand charts etc., stick with the 210.19(A)(3).

 

[don_resqcapt19]

First Atricle 220 has nothing to do with the selection of conductor size. The rule that applies is 210.19(A)(3), but you have apply all of the rule, not just the last part of it.

(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 3/ 4 kW or more rating, the minimum branch-circuit rating shall be 40 amperes.

If the load is over 9.6 kW you can't use the minimum branch circuit rating.
Don

 

[iwire]

Don

First Article 220 has nothing to do with the selection of conductor size. ................If the load is over 9.6 kW you can't use the minimum branch circuit rating.
Don

I am glad you jumped in here as George and I where not making any headway whatsoever. :lol:

I was trying to keep Mike concentrating on 210.19 and only 210.19 but he likes to bounce around the NEC.

 

[jwelectric]

No I am not bouncing around the NEC I am still quoting the last sentence of 210.19(A)(3).

This last sentence clearly states that the MINIMUM circuit allowed for a range 8 ? kw or more RATING is 40 amps.

I am not injecting anything other than this sentence but have addressed the sections as they were presented by others such as the maximum load to be served and table 220.55.
I am not the one trying to change the wording of the last sentence to say anything other than what is being said.
I am the one that has asked to have this sentence addressed and no one has as yet.

An 8kw range could be installed on a 35 ampere circuit, could it not?
8000/240 = 33.33
An 8 ? kw range would be allowed on a 35 ampere circuit.
Then there is no reason to mention the MINIMUM size circuit for a range under 8 ? kw is there?

Now if the words or more rating were removed I would agree with the statement that a range larger than a 16kw would require a circuit larger than 40 amperes but this is not what the last sentence states.
16 ? 12 = 4
4 x 5 = 20
8000 x 120% = 9600
9600/240 = 40 amps

The last sentence is very clear as to the minimum size circuit allowed for a range that is rated at 8 ? kw or more.

 

[iwire]

Mike I respectfully say you are mistaken.

Please for your students at least consider the possibility you are reading this section wrong.

This last sentence clearly states that the MINIMUM circuit allowed for a range 8 ? kw or more RATING is 40 amps

Mike we all have seen it, we just don't read it the way you do.

I agree with Don, George and Rick that what that means is 8.75 KW to 9.6 KW will be supplied by at least a 40 amp circuit.

Once above 9.6 KW the minimum required circuit becomes inadequate and we must use a larger OCP.

Do you think your interpretation makes the least bit of sense? :?

 

[iwire]

9600/240 = 40 amps

Yes Mike that works fine and the 40 amp circuit will be fine for a 9.6 KW range.

Keep in mind that the NEC recognizes ranges up to 27 KW.

Lets say we have a range that is 27 KW @ 240

27,000/240 = 112 amps making a 40 amp circuit woefully undersized and a violation of 210.19(A)

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.......

The 27 KW range on a 40 amp circuit would also directly volatile the part of 210.19(A)(3) that seems to be invisible to you.

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.

 

[infinity]

I agree with Don, George and Rick that what that means is 8.75 KW to 9.6 KW will be supplied by at least a 40 amp circuit.


Do you think your interpretation makes the least bit of sense? :?

Bob, you can add me to the list. I can see this being a 10 page post but I'm not sure why that is so. The articles that you've posted seem quite clear.

 

[jwelectric]

Once again every thing except the last sentence of 210.19(A)(3) has been addressed.

I would be more than glad to agree with you if the last sentence stated that ranges rated 8 ? kw through 9.6 kw but this is not the case is it?

When reading the code it progresses with the rules or in other words the next section or article can amend or modify the sentence, section or article that comes before it.
In 210.19(A)(3) it is very clear that the very last sentence addresses a range that is rated 8 ? kw or more.

This sentence modifies the sentence just above it by allowing any range that has a rating of 8 ? kw or more to be installed on a minimum 40 ampere circuit.

As I have asked more than one time could someone explain away these words that are found in 210.19(A)(3)
For ranges of 8? kW or more rating, the minimum branch-circuit rating shall be 40 amperes.
Am I as an electrical contractor or instructor supposed to say that they don?t exist?
Am I as an electrical contractor or instructor supposed to change the words 8 ? kw or more rating to say between 8 ? and 9.6 kw?

I have a hard time believing that anyone can not see the words as they are written. It is very clear to me that the intent was to allow a 40 ampere circuit to be installed for any one range or the wording of that sentence would have been different to reflect the thought of 8.75 through 9.6kw.


Now I am going to church.

 

[jeff43222]

Now that we're all in agreement and everything's been cleared up...

Would anyone care to venture an opinion as to what size circuit I should install for this 14.4 kW range? Here's my take:

220.4(C) says demand factors for range loads can be applied according to Table 220.19. That table's Note 1 gives the rule about adding 5% to the demand load in column C for each kW over 12 or major faction thereof. Notes 2, 3, and 4 don't apply since this particular installation involves a single range rated over 12 kW.

The range's nameplate says 14.4 kW for a 120/240V installation. Going to Table 220.19, Column C, we start with 8 kW. Note 1 says we subtract 12 from 14.4 to get 2.4. We then drop the 0.4 because it's not a major fraction, so that gives us 2 x 5% = 10%. Add it all up, and we get a final demand load of 8 + ( 10% of 8 ) = 8.8 kW. 8.8 kW ? 240V = 36.66A.

So the end result is that I can install a 40A circuit for this 14.4 kW range. Also legal (and perhaps preferable) would be a 50A circuit, as we've only been talking about minimums. Who's with me?

(I just noticed that the relevant section/table numbers in the 2005 NEC are different from those in the 2002 NEC. It looks like the information is the same, though. My references are to the 2002 NEC.)

 

[iwire]

I have a hard time believing that anyone can not see the words as they are written.

And I believe the rest of us feel the same way about you. :lol:

It is very clear to me that the intent was to allow a 40 ampere circuit to be installed for any one range or the wording of that sentence would have been different to reflect the thought of 8.75 through 9.6kw.

Mike if they meant what you think they mean the wording would be different.

It would say something like

The maximum size required is....

Why is it you believe a minimum requirement is also the maximum requirement?

Now I am going to church.

Thats good maybe some divine intedirvention will hit you and you will see the light. :lol:

 

[iwire]

Now that we're all in agreement and everything's been cleared up...

Trouble maker. :lol:

Would anyone care to venture an opinion as to what size circuit I should install for this 14.4 kW range?

Only one option run 3 AWG copper and tap the service conductors without any breaker. :wink:

I will think on your question and get back to you with a real answer or at least my opinion.

I can tell you that I would most likely run a 60 amp circuit for this 14.4 KW load but that is not code minimum.

 

[Cavie]

Jeff. In my study of the 2005 v. 2002 I have found that MANY of the ART # and ref. have changed. Many of my fellow inspectors thaink that there are not many changes to the code but there is enought to scramble the Ref #'s. this does become a problem in studying for the Test for 2005 while inspecting for 2002 with memery of 1999 as last code while working in the field.

 

[jeff43222]

I just took my continuing education credits a couple months ago, and I was pretty surprised by all the code changes. In this case, though, I think the information is the same; just the section/table numbers are different.

I'm glad I don't have to take any more tests on the code. 8)