Commercial Service Calculation - Deep Dive
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- Опубликовано: 10 июл 2024
- This video is a thorough, step-by-step analysis of a commercial service load calc, using a retail store (with restaurant) as an example. A complete, yet concise table format makes it quick and convenient and can be used on virtually any commercial calc.
Please check out my channel for videos of other types of calcs, etc.
/ @simply.electrical
See my website for more info:
howtofixit.net/electrical-loa...
Electrical NEC Exam Test Load 2020 Table Feeder Master Journeyman Apprentice Electrician, Calc, Calculation, Service
Excellent explanation. Thank you so much for your time. Really helpful to see how you went through it line by line. I tend to always think I am missing something since the code is a bit convoluted trying to cover all scenarios. Thanks again.
You're welcome! No doubt, the code is anything but straight-forward. Glad you found this helpful. Thanks for the comment!
Great video.
Thanks!
I've been banging my head against load calc for the past couple weeks and I have to say that your video, BY FAR, is the best, most thorough, in depth, precise tutorial on how to do commercial load calc (or any load calc for that matter) on RUclips. It's not only incredibly thorough, your layout is beautiful. Seriously. I've gone from rewriting & condensing notes in 220, trying to figure it out, to making a spreadsheet or load calc calculator, to using the Line Method with a shit ton of notes, to finally landing on your most excellent video and yours is the best. You cover something that only ONE other guy mentions, which is continuous load, and you even explain WHY you're using it where you're using it.
We are all so lucky to have you.
One question. I'm preparing to take my test, which, sadly, is still 2017. Do we assume continuous load is included in Table 220.12? I ask, because the continuous load note at the bottom of Table 220.12 in the 2020 NEC is not in the 2017 NEC, and I've scoured the interwebs for an answer and nobody mentions it.
Hey, thank you so much for the incredibly kind words! Sorry, I've been away for a bit and the comments piled up.
As for T220.12, you'll notice that the values are different between the 2017 and 2020. That's because they added in the continuous load factor in 2020. So, on a 2017 exam, you will need to account for it yourself, if necessary. In my experience, most exam questions aren't detailed enough to expect you to factor that in, but just read it carefully. When in doubt, try it both ways and see which result fits an answer option. Sometimes that works. ;)
@@simply.electrical Thanks. And, I passed on the first try.
@@icevariable9600 That's awesome! Congrats!
Thank You for sharing this is great informatiom.
You are very welcome!
UAU thank you for your quick reaction on may answer it is unexpected . thank you very much!!!!!!!
You bet. Check it out here:
Duplex Standard Calc: ruclips.net/video/9kiYYCs3m5Q/видео.html
Excellent video😍
Thanks!
never mind 125% is right thanks for the great videos :)
I see you were able to make sense of the NEC example. I'm not a big fan of the examples in the Annexes, simply because I don't think they do a very good job of explaining themselves. It leaves you scratching your head more often than not, IMO. That said, they are helpful if you have no other resources to draw on.
Thanks for the comments!
Very nice, thank you
Thanks, you bet!
great information
Glad it was helpful!
amazing video, can you continue this video and help to find feeder size and also designing branch circuit for such system ?
Yes, I do plan to expand on these videos in the near future. Unfortunately, I can only do so as time allows. At the moment, I'm not sure how soon it will be. Thanks for your interest!
@@simply.electrical Thank you
The service amps is 503. You would have to go to table 240.6(A) to find the standard breaker size. You can’t use the standard 500 amp breaker because your calculated load is over that. The next standard size is a 600 amp breaker. Go to table 310.16 and go to the 75 degree Celsius column. Find the wire size that has an ampacity of 600 amps or more. The service wire size will be 1500 kcmil Copper or parallel runs of 500 kcmil Aluminum.
I am studying for my Washington master exam and your videos have been extremely helpful. I think I have watched all of them and am much more confident taking my test tomorrow. I am wondering about taking your show window, track lighting, and sign loads at 125%? I understand that they would be continuous loads but what if they don't use the show window? In annex D example D3 (store building) they have a sign and show window in the calculation at 100% not 125%. What would you do on a exam?
See comment below...
I recently took a load calculation exam on the 2020 NEC. One of the questions gave me a two tennant manufacturing facility. One of the tennants had (5) 60 amp transformer arc welders at a 10% duty cycle. How does that load get calculated? Article 630 has a duty cycle table that I don't know how to read, and 630.12 talks about 200% conductor ampacity for the OCPD.
For the exam I took it as (5) 60 amp loads with no demand factor, but I'm certain that isn't right. Can you offer some insight?
Welders throw a lot of folks for a loop. And the question they gave you on the exam was tricky because they gave you intentionally misleading information. The duty cycle has no bearing on calculating the load for a GROUP of welders. So that bit of info was meant to be a curve ball. Table 630.11(A) only applies to an individual welder.
For a GROUP of welders, apply the percentages specified in 630.11(B). Add the values together to determine the minimum CONDUCTOR ampacity (60+60+51+42+36=249A). This would be your MINIMUM load value for welders in your calc. You would plug this number into the table under Other Loads [220.14(A)] in the table from the video.
Side note FYI: Once you have the conductor ampacity, see 630.12(B) if you want to find the max OVERCURRENT PROTECTION rating for one or more welders. Take 200% of the conductor ampacity to get your MAXIMUM load value in amps (249x200%=498A). This would apply to your branch circuit (or subfeeder) OCPD -- not your service. So this would NOT be part of your calc for the exam question.
This is how I interpret and apply article 630. Hope this helps!
I had a question come up where it was single family dwelling using ( Optional Method ) but the calc said the dwelling was running on a
generator and not utility does that change the calc at all?
No, a service load calc simply establishes the minimum load of the building. It makes no difference what the power source is. It could be powered by a generator, solar panels, wind turbine, exercise bicycle/magneto combo, or the Tesseract - doesn't matter. However, whatever it is, pay attention to the voltage because that tells you how to find amps.
The state exams will often times put in extra information that has no bearing on the problem - just to throw you off. They're trying to make sure you really know your stuff.
@ericpolk9004
0 seconds ago
so in the 2017 NEC the 125 percent need to be added? to the general lighting load?
That's correct. You'll notice that the note for Table 220.12 was added in the 2020 NEC, stating the inclusion of the 125%. And you can see that the values have all been adjusted accordingly. They did a whole re-vamping of the table in 2020.
Thanks i appreciate your channel I'm up too 15 masters now and you have helped tremendously @@simply.electrical
Hello, What about washer , dryer load in commercial building like hotel, motel? Just one per whole building.
Those would fall under 220.14(A). Part III of 220 does not provide any demand factors for commercial laundry loads, so they would be calculated at nameplate value.
I had a question pop up that i got wrong any advice see below:
Step 7 - A/C Load
The total VA load for the AC should be calculated as follows:
24 A × 240 = 5,760 VA
This load is included at 100% in this question shouldn't it be 125 % since it is the largest motor?
This is a Store
Did they tell you that the A/C load was indeed the largest load of the building? Because on a test, you are not expected to assume. They will give you that kind of pertinent data.
Some people add the extra 25% during a different step, so could they have perhaps done that? Hard to know without seeing the whole problem.
Was this a test, or maybe a practice test, or worksheet?
@@simply.electrical it was the only motor in the calculation but taken at 100 and not 125 seems wrong
No mention of heat or any other motors
Practice Exam
@@ericpolk9004 One thing to note about practice tests: Many of them are imperfect. They can be written by well-intentioned folks who are trying to help, but they do have some mistakes sometimes. I'm not saying that is the case here, but it's a possibility. I'm not sure where your practice test came from. Can you reach out to them to see how they arrive at their answer?
The state exams tend to be more vetted and accurate. Often times, on a state exam, the calc problems will be very abbreviated. They are not looking for a whole service load calc most of the time. So you won't treat it quite the same way. You just need to give them what they ask for.
Can you do a duplex ? I had 2 questions on test for a duplex standard calc and optional calc for a duplex
Hey Seth, sorry for not responding to you sooner! I was away for a bit.
You must use the standard method for a duplex --- BUT --- 220.85 allows you to calculate it under the optional method AS A TRIPLEX and take the lesser of the two totals. I'll put together a duplex video soon.
Here are my Multifamily videos:
Multifamily Optional Crash Course - ruclips.net/video/zRKbEu2zNWM/видео.html
Multifamily Optional Deep Dive - ruclips.net/video/CzIiZwBkNNU/видео.html
Multifamily Standard Crash Course - ruclips.net/video/0Ryf2QlmO-k/видео.html
Multifamily Standard Deep Dive - ruclips.net/video/laZ4THu15Hs/видео.html
Let me know if you have any questions. And thanks for checking out my channel!
James
Here it is! Duplex Standard Calc: ruclips.net/video/9kiYYCs3m5Q/видео.html
Hello, where shall I put landscape lighting in my commercial building?
Since landscape lighting isn't specified under article 220, it would have to go under Appliances. It falls under the definitions of "Appliances" and "Utilization Equipment". However, don't forget to add 25% for being a continuous load!
What about washer , dryer load in commercial building like hotel, motel? Also in appliences?@@simply.electrical
You’re a fantastic teacher. Your lesson is too polluted with ads though. I understand monetizing your content but this was ridiculous.
Hey David,
I don't monetize my videos. I don't have near enough subscribers to monetize (need 1000 min). This must be RUclips doing that on their own. I'm sorry to hear that there are a lot of ads. When I watch them, I don't see any ads, but that's probably because it's my channel.
But thanks for watching my video. Sorry about the ads!
I didn't get a single ad when I watched this video.
is there an optional method for this calculation?
Optional calcs only apply to occupancies covered in part IV (220.80-88): residential (220.82-83), multifamily (220.84-85), schools (220.86), existing loads (220.87), and new restaurants (220.88).
so in the 2017 NEC the 125 percent need to be added?
That's correct. You'll notice that the note for Table 220.12 was added in the 2020 NEC, stating the inclusion of the 125%. And you can see that the values have all been adjusted accordingly. They did a whole re-vamping of the table in 2020.
PLEAS do duplex! Thank you.
Hey Nicolae, thanks for visiting my channel. You're the second request for a duplex, so I'm putting one together now. I'll hopefully have it posted in a day or two. - James
Here it is! Duplex Standard Calc: ruclips.net/video/9kiYYCs3m5Q/видео.html
how to monetize your channel ?
At this point, I'm just trying to build the channel. If you would be so kind as to spread the word to anyone you think might be interested, I would be so grateful! Likes, subs, and comments help a ton.
Thanks!
I’m studying for the Oregon General Supervisor exam (which it brutal by the way), but maybe this question isn’t the best example because it is so generic. They didn’t include equipment voltages. What if the heat was (3) 15000W, 1PH, 208V loads?
Can you please do a an example on a more challenging question, like a restaurant without just wattages and a mixture of 1ph/3ph loads?
Yes, Oregon is tough. When I took mine 20 years ago, they had trick questions on the exam. Some questions had no correct answer and others had more than one correct answer. They provided us with scratch paper so we could explain which answers we chose and why.
Like you said... BRUTAL.
If they don't include the equipment voltages, there are two possibilities: either the voltage isn't necessary to know for the answer, or there is enough information given in the question to determine the voltage via Ohm's Law. An Ohm's wheel chart is super helpful, if you don't have one.
ohmslawcalculator.com/ohms-law-wheel
If you have (3) 15,000w heating loads in commercial, just add them together (assuming they are not noncoincident with larger loads), regardless of the voltage or phasing.
If you have a load calc question that has several 1ph and 3ph loads, go to Table 430.248 and Table 430.250, respectively, to determine the FLC. Multiply the FLC by the voltage of each motor to get your wattage (don't forget your 3ph multiplier - 1.732). They must either provide the voltage or else provide the means to attain the voltage within the question. Otherwise, no solution is possible.
Hope that helps at least a little. Let me know if I misunderstood any of your questions. 🙂
Why didn’t you balance the loads between phases?
Thanks for the question. Before I address it (I don't want to assume), which specific loads are you inquiring about?
Sorry, I posted my response in the wrong area.