I came up with 305 Amps for the optional method.
Fun practice Service Load Calc.
- Thread starter Konen
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NAjxBUEEdA7PoKoX7vD2
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6750 lighting
5450 appliance
8000 cooking
5000 dryer
4080 air conditioner
29280 feeder
29280 * 6 = 175680
175680 * 44% / 240 = 322.1
- Location
- Connecticut
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- Engineer
The dryer is 3500...
6750 lighting
5450 appliance
8000 cooking
3500 dryer
4080 air conditioner
27780 per dwelling unit
27780 * 6 = 166,680
166680 * 44% / 240 = 305.6
NAjxBUEEdA7PoKoX7vD2
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That would be true for optional.
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- Connecticut
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Yes...Optional Method...305.6A, not 322.1A
NAjxBUEEdA7PoKoX7vD2
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Konen
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I think the neutral calc is incorrect. It is using the water heater as 120v load. Although it doesn't state 120 or 240 one usually assumes 240v on the water heater so no neutral load there. I stand by 230 amps for the neutral until I find another of my mistakes.
Konen
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Yeah I've noticed that a bunch in this book, they have done it on all the calculations on the water heater loads. I'm taking note and not factoring it a neutral load when I'm practicing my load calcs.
Dsg319
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Is that a Ray Holder study book?
Konen
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Has anyone here ever done their own calculation on "Example D3(a) Industrial Feeders in a Common Raceway" in Annex D in NEC 2020. It's throwing me for a loop.
Maybe I'm missing something but they never add 25% to lighting for continuous. And then when they add the adjustment/correction factors for T310.15(C)(1) & T310.15(B)(1) they remove the 25% added to the continuous use dryers.
Side note: Just to make sure, you decide your overcurrent protection before adjustment/correction factors, the adjustment/correction factors are only for calculating the ampacity for the desired wire size?
Maybe I'm missing something but they never add 25% to lighting for continuous. And then when they add the adjustment/correction factors for T310.15(C)(1) & T310.15(B)(1) they remove the 25% added to the continuous use dryers.
Side note: Just to make sure, you decide your overcurrent protection before adjustment/correction factors, the adjustment/correction factors are only for calculating the ampacity for the desired wire size?
Konen
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They do add 25% to the lighting (and to the Industrial Process heaters.) 56,600VA * 125% (continuous) + 38,900VA (non-continuous) = 109,650VA...(they've rounded to the hundreds, not sure why.)
And yes, the calculation for adjustment/correction factors should be without the 25% for continuous loads (NEC 215.2(A)(1)(b)).
Konen
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Ok awesome thanks! I see it now for the lighting, they added them together near to top and applied the 25%.
I'm referring to 4th "paragraph" under "ungrounded feeder conductors", when they apply the correction/adjustment factors, they remove the 25% they added for continuous. Is that correct?
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Yes. Per 215.2(A)(1)(b)
Konen
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Oh I see, so this is another one of the "whichever one is bigger"
Option 1- 215.2(A)(1)(a) The ampacity of not less than 100% noncontinuous + 125% continous (with no adjustment/correction).
Or
Option 2- 215.2(A)(1)(b) 100% of the load with adjustment/correction factors.
Dsg319
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Nope I’ve used several of his books. I like them, but have found a mistake or so.Yes, is that bad?
Konen
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Oh
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I would bet it is near impossible to write one of these books and not have a mistake here or there.
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