This was an excellent tutorial. Thanks. Greatly needed. I just have one question. At 20 minutes when you're going over AC vs heat, you multiply the AC VA of 4008 VA x 125%, then multiply 4008 VA x 9 units. Why did you multiply by 125%, since we don't know if this is the biggest motor or not, and why the 4008 VA x 9 units?
@@constructionseminars4197 Thanks: 2 follow up questions. 1) Since you're using it for largest motor, why wouldn't you use it for all 10 units? 2) Does it say in the NEC to ignore the heat (if it's larger than AC) or is it just common practice to ignore heat for largest motor, given that it's larger than AC?
@@icevariable9600 You only include the 125% on the first A/C motor, the rest would be at 100%. The largest motor is just one unit. If all 10 are the same, you just use one of the 10. A/C and heat are considered non-coincident load (loads that don't happen at the same time) when you have non-coincident loads you only include the largest of the two loads, and toss out the smaller per 220.60
@@constructionseminars4197 Damn! That's right! I knew that about the largest motor, but, for some reason it didn't register as I was going through the video. Thanks.
In the example at 20 minutes, I am using one of the A/C units as my largest motor. It is calculated at 125% and the other 9 units at 100%. This is compared to the 100% of the heat. The heat was larger, so we tossed out the air conditioners.
Each unit of a 20 unit apartment building measures 1,500 sq feet with a 5 kw range in each unit. There is a central laundry room located in the building. What is the general lighting unit and small appliance load for each unit? How do I figure this out I need help
It appears that they are asking about the small appliance and lighting load, the fact that there is a range in each unit is not going to be calculated. Also laundry circuit is not included because there is a central laundry room. 1500x3VA per sq ft = 4500 4500 x 20 =90,000 Small appliance 2x1500=3000 x 20 = 60,000 90,000 + 60,000 = 150,000 Reference Table 220.42 First 3000@100% = 3000 3001 -120,000@35% = 40,950 Remaining 30,000@25% = 7500 3000 + 40,950 + 7500 = 51,450 If the question includes the ranges add another 28,000 per table 220.55 column B 20x5000= 100,000 x 28% = 28,000
Range question explanation please. 10 units, 8kW ranges load calc problem (approx 10 min mark). Why after we get the 27.20kW from column B do we compare to column C and take the 25kW as the answer? I can't find that rule in the code. Thanks
@@constructionseminars4197 The answers provided for the 20 8kW range problem (at 10:00 in) only has 27.2 kW as an answer. 25kW (the correct answer) is not one of the options provided.
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Very Kind of y'all to post this for everyone. training classes are expensive and deserve to be, although some of us just cant afford it. Thanks again
Studying for my masters. These videos are great!
Glad they are helpful!
good explanation i really like the way that you explain it, thank you
This is a great instructional video, thank you.
Thanks for the videos, much appreciated!
Good stuff. Easy to understand. Thanks
Glad it helped!
Good job on the video!
Awesome thanks 🙏
This was an excellent tutorial. Thanks. Greatly needed. I just have one question.
At 20 minutes when you're going over AC vs heat, you multiply the AC VA of 4008 VA x 125%, then multiply 4008 VA x 9 units. Why did you multiply by 125%, since we don't know if this is the biggest motor or not, and why the 4008 VA x 9 units?
If no other motor is specified, I am assuming the AC motor is the largest motor
@@constructionseminars4197 Thanks: 2 follow up questions.
1) Since you're using it for largest motor, why wouldn't you use it for all 10 units?
2) Does it say in the NEC to ignore the heat (if it's larger than AC) or is it just common practice to ignore heat for largest motor, given that it's larger than AC?
@@icevariable9600 You only include the 125% on the first A/C motor, the rest would be at 100%. The largest motor is just one unit. If all 10 are the same, you just use one of the 10. A/C and heat are considered non-coincident load (loads that don't happen at the same time) when you have non-coincident loads you only include the largest of the two loads, and toss out the smaller per 220.60
@@constructionseminars4197 Damn! That's right! I knew that about the largest motor, but, for some reason it didn't register as I was going through the video. Thanks.
Confused,why would I not use the a/c motor which uses 28 amps as largest motor?no disrespect meant, learning a lot Thanks!!!
In the example at 20 minutes, I am using one of the A/C units as my largest motor. It is calculated at 125% and the other 9 units at 100%. This is compared to the 100% of the heat. The heat was larger, so we tossed out the air conditioners.
Each unit of a 20 unit apartment building measures 1,500 sq feet with a 5 kw range in each unit. There is a central laundry room located in the building. What is the general lighting unit and small appliance load for each unit? How do I figure this out I need help
It appears that they are asking about the small appliance and lighting load, the fact that there is a range in each unit is not going to be calculated. Also laundry circuit is not included because there is a central laundry room.
1500x3VA per sq ft = 4500
4500 x 20 =90,000
Small appliance 2x1500=3000 x 20 = 60,000
90,000 + 60,000 = 150,000
Reference Table 220.42
First 3000@100% = 3000
3001 -120,000@35% = 40,950
Remaining 30,000@25% = 7500
3000 + 40,950 + 7500 = 51,450
If the question includes the ranges add another 28,000 per table 220.55 column B
20x5000= 100,000 x 28% = 28,000
Range question explanation please. 10 units, 8kW ranges load calc problem (approx 10 min mark). Why after we get the 27.20kW from column B do we compare to column C and take the 25kW as the answer? I can't find that rule in the code. Thanks
Generally on a test, they are looking for the minimum. In the field you can use either number
@@constructionseminars4197 Thank you!
@@constructionseminars4197 The answers provided for the 20 8kW range problem (at 10:00 in) only has 27.2 kW as an answer. 25kW (the correct answer) is not one of the options provided.
Largest motor safety factor? 430.24
430.24 is for sizing feeder conductors to several motors at once. I am not sure how that applies to this calculation.