NEC Table 220.55
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- เผยแพร่เมื่อ 7 ก.ย. 2016
- Perhaps one of the most confusing tables in the NEC is Table 220.55 for household ranges. This table is confusing because the first two columns are percentage multipliers, while the third column is a final kW value. The notes to this table further complicate matters. This video, and the examples given will teach you all the ways this table can be used.
Thank you so much for explaining this. Sat in a four hour class last night and the instructor couldn't explain it anywhere near as good as this.
Man, you're a good teacher. You have no idea how much this helped me. Muchas gracias! 👍👍
Thank you so much! I was stumped on this today and this really helped be understand that Column C is a number not a percentage.
Hands down best video on the internet for range calculation. Better than the study guide that’s in front of me as well!!!
Note 1 and note 2 refer to range, note 3 refers to any cooking appliance between 1.75kw and 8.75 kw. So how to calculate in a multifamily building the demand factor of (for example )10 cooktops of 9.6 kw , or 10 ovens of 14 kw, Congratulations on the quality content of this channel
One of the better videos I’ve seen. Thanks for showing the math.
Awesome video and explanation. Simply perfect!!
Thank you 😁
I watched all of your videos. THIS video makes you a rock star! Well Done! I am looking forward to your future videos. Frank YOU ROCK!
Thanks for this video. Was having trouble with a practice question, and this video cleared it up for me. Great explanation and visuals.
excellent lesson , learned everything I forgot over the years!
You explain this very well. Thank You.
My Oregon State exam is tomorrow and i am so thankful for this review! we went over this in class over a month ago, and this was a very clear, easy to follow review! thank you so much!!
thanks for clearing up column C...you guys rock...
Appreciate putting this together.. was very helpful
Well done thank you for taking the time to make it.
Excellent pace.
thanks for uploading ! this was extremely helpful with my homework.
I've been studying Article 220 for close to two months now. For this specific section pertaining to ranges, 220.55, this was amazing. This is, by far, THE best instructional video on that section. You have no idea how this has helped me.
dumb question.. if the percentage is 20% why does he multiply by 1.2? isn't 1.2 = 120%?
This was very helpful i was stuck for almost two days
E-Tech Professor
I would to thank you so much for your fantastic video
I’m taking the PE exam in power on April 2019 I know this table is very important and I was confused because the 5 Notes were unclear to my understanding but after your video I felt better and easy to solve problems
I greatly appreciate it
You have amazing skills how to teach
I would like if you don’t mind to upload more videos for other tables in the NEC Code book please
I look forward to hearing from you
Thanks again
Appreciate this video!
This is the greatest video and explanation i have ever seen .. My master electrician exam is tomorrow and this video really helped me
Best wishes on your exam!
The 1.2 was throwing me off as well. Great Video though! I am taking my code exam In a week and this video was great for some of the questions I had on my practice exam. Thank you.
Why the 1.2?
very helpful thank you!!!
Excellent
Awesome job I’ll explain it
Thanks for info
Pure gold
Perfection.
Your my hero! There was a day where I kept asking my instructor questions about the steps he took because I did not understand the way was doing it on the board. What does he do? He becomes so frustrated with me that he asks me to take my stuff and leave. Basically the near entirety of our class failed the test on this table in the NEC.
Fathomistic Fantasy that’s just a sorry instructor who can’t convey his message
@@kennethcarroll5420 he was capable of teaching me one thing though. I learned that I can't rely on my disability as an excuse. I have to work with what I am capable and make up for the difference. My extra effort will pay off.
What is the demand wattage load for an AC 2 ton condenser unit whose wattage is 7000w, is there a formula?
I have two ranges both 10kw demand load under column C the demand would be 11,000 watts. How would I show that 11,000 watts on a panel load schedule? Split evenly between both ranges 5,500(2750 on each leg) or would I do 8,000 on stove #1 and 3,000 on stove #2?
think video need do over 😞
when I thought I got , now lost
1.2?
I read several comments of explanations & linked sites
Still Confused.
On Question 8, shouldn't we be using the line for 10 appliances total instead of the line for 5 appliances twice? It would give a smaller final number due to diversity.
At 11:40 the 22.8kW is numerically correct, but
if all units are treated as 6kW the demand factor calculation for 10@6kW is 20.4kW, and
if Note 3 allows averaging all units, 10@4.5kW gives 15.3kW
Excellent observation, and that is how I would approach it in design also. But on the master electricians' exam the literal wording of note 3 needs to be used. "Where the rating of cooking appliances falls under both Column A and Column B, the demand factors for each column shall be applied to the appliances for that column, and the results added together." There is no provision to assume a larger unit nor is there a permission to average in this note. See 90.5(A) on the use of the word "shall."
By that logic, if you have 10 x 6kW units, you'd need 20.4kW, but if 5, of the 6kW, were replaced with 3kW units, the service would need to be upgraded to 22.8kW.
Note 3 effectively lumps A and B together for mixed appliances, and defines a lower limit for "A" at 1.75kW.
Then it explicitly permits using A or B - in lieu of C - with the A/B choice dictated by the calculated average.
Consequently, the calculated average can only be: - in A range - or in B range.
I'm having difficulty finding how any mathematical average could ever be below the "A" range with the lower limit set in the opening sentence.
The only way, I can fathom any logic, is if numerous small units rated below 1.75kW were included in the population, but such small units are not permitted to be included in the population count. If small units were included they could indeed produce an average below 1.75kW; and smaller units are more likely to not benefit from any statistical load diversity.
The second half of Note-3 final sentence wants to re-segregate units if the average is below A and B, but an average below A seems, to me, to be a mathematical impossibility, hence the "below A and B" seems mathematically nonsensical.
Are electric ranges to b calculated at 100 percent of name plate rating?
No only 1 mounted cooking unit has to have nameplate rating. One range can be calculated based on table 220.55
There is a better formula for that. They gave it to me when I was preparing for the test
16kw-12kw since it exceeds 12kw
That leaves you 4kw more and it tells you that if it exceed more than 12kw you have to add 5 percent more for each kilowatt.
5% times 4kw=20kw
If you go to 220.55 it says for 1 appliance not over 12kw is 8 so you multiply .20x 8000= and then add back 8000 again and that’s it
Thank you for the comment. Multiplying 8kW by 1.2 is the same as multiplying 8kW by 0.2 and then adding it back to 8 kW. The method I teach is the way the textbooks commonly used by trade school instructors teach it.
Great tutorial question 11 how did you get 8 kilowatts.
I’m so confused about the 1.2 still. Need help on this.
8 X 1 = 8 or 8 X 1.2 = 20%. If it was 1.25 it would be 1/4%. Hope that makes sense
Thanks>
Question #7 I see in the notes that it says on note 1. over 12kw through 27kw. We are below that 12kw. Sitting at 8.5 Kw. Which that tells me to use column B. Why was Column C was still used. Then if you say, column C says up top not over 12kw. If your using it from the value of zero kW up to 12 kw. Then why even have column A and B for ranges of the same rating? How does this help someone but confuse them on a test? Please explain the remedy to this. Thx for your helpful video :)
in other words it seems like column B's cut off point would be 8 3/4 KW. Anything over that I would use column C. Make sense?
You have to take all of the table notes into consideration: The heading tells you to use Column C unless permitted by Note 3. Note 3 is an alternate method (in lieu of = instead of, and it is a permission, not a directive). For ten 8.5 kW ranges you could use Column B but it would give you a higher value than Column C. On the flipside, if you only had one 8.5 kW range, then Column B would give a better (lower) value than Column C.
I have a question that I have been provided the answer but each time I attempt to solve, my calculation is approximately 5A less. What is the demand load, in amps, for a single circuit supplying one wall-mounted oven rated 11.75kW, 1Ø, 240V and a countertop cooking unit rated at 9.6kW, 1Ø, 240V? The answer given is 48.33A.
The given answer is correct. Second half of note 4 applies. Add the two units together and treat them as one. That gives a total of 21.35kW. Note 1 tells us to increase the Column C value by 5 percent for every major fraction of more than 12 kW. --> .35 is not a major fraction so we have 9 kW more than 12. That means that we take the value in column C for one unit (8kW) plus 9 times 5%. or mathematically that turns into 8kW times 1.45 = 11.6kW. At 240V that is 48.33A
Do we size feeder conductors and breaker according to demand load?
The branch circuit conductor and overcurrent device may be sized to this table. See Note 4 of the Table 220.55. Also 210.19(A)(3) gives minimum size of circuit as 40A. eg. 12kW range gives 8kW demand = 33.3A. Install on a 40 A circuit.
@@FFSeiler do you size a 16kw double oven to the nameplate according to note 4?
👍👍
I am still confused.
Can anyone explain me
In question 4
20% added to 8kw or
8KW × 1.2 = 9.6KW
Explain the whole thing & where do you get the 1.2 from? Thank you
20% is equivalent to .2, however if you were to multiply .2 by Column C or 8kw as in your question you would end up with a lower number 1.6 to be precise. However you may notice that 1.6+8 = 9.6. What he is doing is essentially a short cut on how to calculate the percentage added. You could see it as him just removing one step.
for question 7 why did we use colum c instead
If column B gives a higher answer, column C is still available to be used. The permissions for columns A and B are not exclusive, that is to say, just because you are allowed to use them does not mean you must use them, and so the lowest value is chosen. See the table heading and the notes, for how the use of column C is worded. "It shall be permissible" is different than "shall be used".
Question 3 why 15 plus 30 it says 15 plus 1 for each so why is it not 16 plus 30?
So the total of ranges counting as 1KW each added to a base of 15KW. So basically 15+30=45 like he had shown.
Question 9 is 8000watt then not more than 8k 3/4 rule so other210.19(A)(3) rule doesn't apply?
So its not 40 amp shouldn't apply on this right sir ? Because this is less than8750 amp
Great question. The 8-3/4kW applies to the original nameplate value, not the demand factor. The minimum size for the branch circuit shall not be less than 40A because it is actually a 12KW range with a demand factor applied (8kW is 33.3A)
Sorry thank you awesome question & come nice tone voice in control and come with great answer with section sir. Wonderful
So when test talk about circuit load didn't say amp it means amp?
Branch circuit rating too it don't asked amp but they met was amp ?
Island cooking stove count as counter amounted cooking stove? Please let me know
is 20% = 1.2 or 0.2
20% is 0.2 however to increase a number by 20% you would use 1.2 (ie multiply by itself and the extra 20%)
where is note 2 example?
at the very end, bonus question 13
why are you using the 1.2?
1 counts for the whole number being multiplied and the .2 counts for the overage of that whole number to be added to it. So .20 is 20% of 100% in decimal form.
This table makes me want to take 277v across the chest
you need to speak up when making these videos
Cofi Annon it was plenty loud for me, maybe turn your volume up lol
8x20%=1.6
8x1.6=12.8
All your math is wrong buddy. Formulas right. But math is wrong.
The math is absolutely correct. The eight KW is INCREASED by 5 per cent for every KW that the range is more than 8 KW. You may wish to check out other professional resources such as articles by Mike Holt, IAEI Magazine, or Electrical Contractor Magazine to clarify the examples I give, and you will find that they do the math same. Here is one article with further examples.
www.ecmag.com/section/your-business/article-220-cooking-equipment-calculations-part-vi
Good Luck!
You're not multiplying 20% by 8. You are adding 1 appliance. 1 + .2
E-Tech Professor
I would to thank you so much for your fantastic video
I’m taking the PE exam in power on April 2019 I know this table is very important and I was confused because the 5 Notes were unclear to my understanding but after your video I felt better and easy to solve problems
I greatly appreciate it
You have amazing skills how to teach
I would like if you don’t mind to upload more videos for other tables in the NEC Code book please
I look forward to hearing from you
Thanks again