Welcome! Simply Electrical has videos and other information that is designed to be helpful for both the professional and the DIYer. Over the years, as I either studied for various exams or searched for answers to on-the-job or theoretical questions, I wasn't always able to easily find exactly what I was looking for. So I decided to share some of what I've learned from 27 years in the electrical trade with others. Hope it helps!
As I presently have other time commitments, I won't be able to tend to this channel as often as I'd like to, so please bear with me as I incrementally build and maintain it. Thanks for your patience!
Yes, except 350 kcmil Cu is adequate for 302A. 240.4(B) allows the next higher rated OCPD. We aren't given enough info to apply any correction or adjustment factors.
Very helpful thank you. I’m curious why the other loads category did not include 125% continuous load demand increases for an appliance like a ceiling fan.
This is a bit of a gray area. It's all based on "expectations", per article 100 (definition of ceiling fan). There are many loads that COULD be operated for more than 3 hours at a time. But unless you know for sure that it is a typically continuous load, the default would be to take it at 100%. You're right, though. A ceiling fan is one of those loads that easily can be run for extended amounts of time - especially in a commercial application. Technically, it would be advisable to figure it as a continuous load if you know what the operation schedule is. However, in my experience, on an exam, they won't expect the test-taker to jump to conclusions on what is and is not a continuous load. That would be quite unfair. They will inform you as to the continuous loads (except lighting) within the question. Always answer according to the data given. In the real world, the ceiling fan load is so minimal, it will not usually affect the outcome to any significant degree. "Usually" being the key word. ;)
Where are you getting the yellow box on your calculation sheet to add 25% of largest motor of building. Its not listed anywhere in article 220.84 to add that.
This video is for a Standard Calc, not the Optional Method. 220.84 is for the Optional Method for Multifamily. If this was the Optional Method, you're right, we would not take the extra 25% into account. But in case you're wondering about the Standard Method, I'll give a quick rundown. This one is tricky, but here is the logic behind it: 220.50 tells us to calculate motor loads according to 430.24 and a few other code sections. Section 430.24 deals specifically with motors on a feeder ("Several Motors or a Motor and Other Loads"). This requirement tells us to take the largest motor at 125% and the rest of the motors at 100% (125% if continuous). So we must apply this to our load calc since we are sizing a feeder/service. There are some folks that don't take the extra 25% into account in their calcs. In the real world, it's usually not going to make much difference. But on an exam, it could cause a wrong answer if you leave it off. Note: On an exam, they will give you an indication if they expect you to include the extra 25%. They won't expect you to guess which motor is largest - unless it's obvious, I suppose. See Example D1(b) in the Informative Annex D in the back of your code book. You'll notice they add the extra 25% for the disposer.
Yep. The clothes washer load is handled by the Laundry load @ 1500VA (Left Column, 3rd Row). We are required to use a minimum of 1500VA per laundry circuit. I have an in-depth explanation of this here at about the 11:00 mark: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-CzIiZwBkNNU.html
Question. I'm doing a load calculation on a kitchen equipment panel to see if we can add another oven This panel only has kitchen equipment and no lights or general receptacles. Do I just use Table 220.56? Some of them have hood fan as well. Thanks for your time and videos.
Yes, T220.56 would be used for the kitchen equipment only. Hood fans and other HVAC would be calculated separately. This is a situation where you are calculating a feeder load, as opposed to a service. So use the same table provided here, but only apply those loads that are relevant to that feeder (i.e. no lighting, recepts, etc.). See 220.16(B) regarding additional loads to an existing commercial installation.
Your service or feeder conductors must have a 100A capacity or more in order for you to be able to use the optional method in your calculation. If they are less, you must use the standard method (Part III of Article 220).
Quick Question on a Motor What is the full-load running current rating of a 208-volt, 3-phase, 50 hp, squirrel-cage, continuous-duty, ac motor? A: 130 B: 143 C: 162 D: 195 in the code book 430.250 i get 143 amps x 1.25 is 178.75 since it is continous duty I feel like i'm going crazy...
They are trying to trick you. It is a continuous duty motor. But that is just its rating. That does NOT mean it is being used in a continuous duty application. In other words, it is not necessarily being used for more than three hours at a time. But besides that, they are not asking about conductor ampacity. So Part II of 430 does not apply. 430.6(A) tells us to use the appropriate table to determine FLC of motor applications (except for overload protection), which you did correctly (143A). Side note: Also, the inclusion of 'squirrel-cage' is meant to throw you off as well, tempting you to go to T430.52. Doesn't matter. They want to make sure you really know the terminology, and which tables to use, and when not to use them. Answer: B. 143
I have a question on Dryers: Given: you have a (10) apartments each with 4500 VA Dryers what is the total load of the dryers? The test question says nothing about standard or optional... do i use nameplate 4500 VA and 220.54 or do i use 5000 and 220.54 or do i use namplate and 220.84 i notice some test don't say standard or optional some do. So do we assume standard?
The general idea for any load calc is to find the minimum load required. So if they don't tell you which method to use, generally go with whichever gives you the lowest value. That said, I can't speak for every testing agency out there. They may have different expectations in different jurisdictions. I'm going off my own experience and what I've heard from many others. 220.54 states that no dryer can be calculated at less than 5000VA (standard method). So in your case, you cannot use the nameplate when applying T220.54. You must use 5000VA for each dryer. This would be: 5000VA x 10 = 50,000VA x 50% = 25,000VA. Now, it would be very awkward to try to use the optional method here for a couple reasons. This method assumes an entire service calc - not just the dryers. This is because the values are cumulative and interdependent. In other words, you can't mix and match methods. You are not given enough info to merit using the optional method, IMO. But let's say you did use the optional: 4500VA x 10 = 45,000VA First 10,000VA @ 100% = 10,000VA Remainder (35,000VA) @ 40% = 14,000VA 14,000VA + 10,000VA = 24,000VA So we see this would be a lower value when compared to the standard method. But my gut tells me the optional method should not be used here unless they direct you to do so. And in my experience, that has always been the case. I'd be interested to hear other people's input on this. I can see an argument being made both ways on this.
No, you do not have to take 70% for your ungrounded feeder sizing. Perhaps you're talking about calculating the neutral load in 220.61(B)? If so, be sure to look closely at the provisions for that section.
No, you do not have to take 70% for your ungrounded feeder sizing. Perhaps you're talking about calculating the neutral load in 220.61(B)? If so, be sure to look closely at the provisions for that section.
Great information, as usual. I’m taking my admin test in Washington state next week and your videos are super helpful. For the non-coincidental loads, if the largest motor were not the air conditioning, would you then use the whole 125% demand of the largest motor? Or would the same logic apply that because the motor was already accounted for you take 25% of the largest motor and tack it on at the end?
Glad you like the videos! My instinct is to answer yes to both questions, so perhaps I don't fully understand the distinction you're making. No matter where the largest motor is in on the service, you want to take 125% of it's value - unless it's the lesser of noncoincident loads; then you would only take 25% of it. That's my understanding of what they have written in 220.60. But this code section is problematic and needs to be revised. So until they fix it, we have to make an educated guess as to their exact intent. An alternative guess is that they want us to compare the noncoincident loads after taking the motor load at 125%, and then take the larger of the two. This, of course, assumes the motor load is the largest on the service. This is actually the way I personally think noncoincident loads should be treated. But if this is what they intended, their wording is incorrect because they don't even mention anything about the largest motor on the service in 220.60. If you haven't already, you can check out my video on Noncoincident Loads here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_YVvb2YlqUc.html Hope that helps answer your question!
That would make the most sense to me on how noncoincident loads should be handled. I wish that is what the text said. Unfortunately, that is not the meaning that the wording conveys. It would be simple to make that clear, yet they have overcomplicated it. I have submitted a formal petition to the NFPA to revise 220.60, but I'm not holding my breath. They had a chance to fix it after 2020, but arguably made it worse in 2023.
Since this is the Optional Method, almost everything is taken at nameplate value. Check out this video for a thorough explanation of the Optional Method. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pjSYPcfyKx0.html
I understand 220.60 to say, add 125% of whichever motor load is larger to your noncoincident load. say your condenser fan is 3.5 amps, 3.5 x 1.25 =4.375 added to your 220.60 calculation. 120 x 4.375= 525 va.
Due to its phrasing, it's a very tough section to get a clear meaning from. There are two main ways the second sentence of 220.60 can be taken: either as complementary, or as exceptional to the first sentence. The wording specifies that you take 125% if it is NOT the largest of the noncoincident loads. And note that it doesn't say to do so IN LIEU OF the first sentence. It is written as an additional statement, not as an exception to the first statement. So this 125% of the smaller load would be in addition to the largest noncoincident load. In this case, that would be 12,000VA + 8125VA = 20,125VA. A monstrously huge value. If this were the case, what is the point of discussing noncoincident loads if they are simply going to be added together? So, I don't believe that is their intent, but that is how they worded it. However, let's say for a moment that they meant the second sentence to be an exception to the first. Then in this example, we would take ONLY the heat pump load at 125% (8125VA) and eliminate the larger furnace load (12,000VA) from the calc. I certainly don't think that is what they intended either. We'd be leaving the largest (by far) load of the whole service out of the calculation altogether. Anyways, I hope I didn't just add more confusion to the mix! The code-making panel has some more work to do before the next NEC gets printed, IMO.
Any load that is not part of a particular unit's feeder is considered a "house load". This primarily applies to multifamily buildings where there is a panel that supplies loads for common areas (like parking lot lighting, corridor lighting, fire alarm equipment, etc.). The bill for these loads are usually split among the occupants and are on their own feeder and meter. Since they are not included in an individual unit's calculation, they must be tallied up separately and then added to the total. House loads are typically figured under the commercial calc, but check with your jurisdiction.
House loads are typically figured under the commercial calc and then added to the total. I haven't made a video for it yet for a few reasons: 1. There are so many varieties of house load arrangements, it would be nearly impossible to cover all of the types. Different jurisdictions may treat them differently since they are not explicitly covered in the NEC. 2. The commercial calc is very straight-forward and it is easy to plug the loads in as if it was a commercial building. 3. I'm in the middle of producing my 2023 series and am spending my time on those. I would like to do a house load video eventually but it is lower priority at the moment.
No, I haven't, simply because there is no universal way to treat them. House loads are generally done according to Part III of Article 220 (see 220.84(B)). Typically, you would just use the commercial calc table (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-1tQAf7lw-Uw.html) for your house loads, and then add them to your multifamily calc. But this may change from jurisdiction to jurisdiction. Some municipalities may treat house loads as commercial, and some as part of the multifamily. You will have to check to be sure in your area. In my area, we treated large house loads as commercial in most cases. Little quad-plexes and such that might have a tiny house panel for site lighting and common area lighting would just be included with the multifamily calc. Maybe other folks here can chime in with their experiences. If I were taking a test, I would go with the commercial route, since that's generally accepted as the codebook answer.
@@simply.electrical does including it with the multifamily calc mean just counting the 3x VA/sq. Ft then the appliances/ motors at nameplate with no additional things like SABCs/laundry
@@86aoshi I'm only talking about the very small multifamily buildings that have a tiny house panel with a few common area lights, etc. on it. In those cases, we just treat it like it's part of one of the units. It's such a negligible amount, it really doesn't affect the total to any significant degree. However, if it is a larger house load panel (with perhaps laundry facilities, workout room, pool, etc.), I would treat that panel as a commercial calc, and then add the result to the "House Loads" part of the table in this multifamily calc. Hope that helps!
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!
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?
You are absolutely right. I must have fat-fingered the calculator. I apologize! No matter how many times I check my work when making these videos, there always seems to be something that gets overlooked. Thanks for bringing it to my attention. I'll make a note in the video at that point.
EV chargers would fall under appliances in 2020. However, in 2023, a new section was added - 220.57. This changes two things: 1) It requires a minimum rating of 7200VA (or nameplate, if higher). 2) Also, it no longer allows the 75% demand factor to apply (4 or more appliances) in 220.53.
It depends on your situation. I would generally recommend the optional method for most applications. It is quicker, easier, and doesn't require as much detailed data collection. However, the standard method is more precise. So, if you are using the optional method, and end up close to a service size limit (say, you calculate185 amps), then it would be good to run it through the standard method also. You don't want to cut it too close on a 200 amp service. ALWAYS leave plenty of wiggle room, if you can. Keep in mind, that there are rare occasions where a standard calc actually comes in lower than an optional calc. Usually only on tiny buildings.
@@jirehelectric I'm working on getting the tables available for download. I'm putting together a website in my spare time and unfortunately it's taking a little longer than I'd hoped. I'll send out a notification when they are ready. Sorry for the wait!
@@simply.electrical That would be great. I just got my electrical contractor license and I have been working on sizing a 6 dwellings units service plus house, the square footage differs from each other and your videos have helped a lot so you explain more clearly that others on you tube and because sometimes there is no time to go all the way to the process a template would help a lot. Thanks for your hard work. 👏 Sorry for my English I am second English speaker.
Hi Dustin, I really appreciate the offer. I'm no Excel wiz by any means, so that process is taking a bit longer than anticipated. So what I plan to do in the interim is make the tables available as printable forms - to copy and practice on. You would still have to do your own math, but at least all the criteria would be given. That's the best I can do at the moment. Hoping to have those available soon. Once I have it done, I'll post the link on every video. Thanks!
Any extra motor loads would fall under 'Appliances'. Only the largest motor of the building gets the extra 25% added. So if one of your motors is larger than the heat pump, that is the load you would add 25% to - not the heat pump. See 220.53 for appliance criteria.
Unfortunately, I'm still developing my website. At the moment, the best way to get the tables is to screenshot and print the black and white copy that I put at the end of each Deep Dive video. Eventually, I'll have the tables made into fillable spreadsheets. That way you can just input the data and it'll auto calculate. Sorry for the wait!
Thanks! Unfortunately, I'm still developing my website. At the moment, the best way to get the tables is to screenshot and print the black and white copy that I put at the end of each Deep Dive video. Eventually, I'll have the tables made into fillable spreadsheets. That way you can just input the data and it'll auto calculate. Sorry for the wait!
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.
Nice catch! I apologize for that mistake. A 7kW range is unusually small, and I'm so used to using Column C (especially for a single-family calc) that I defaulted to it. You are totally correct, though. Column B should be used here in order to get the minimum load. I'm so grateful for everyone's comments pointing out these kinds of errors. You keep me on my toes! I've made a note on the video at that point, so going forward, folks will be warned. Thanks for bringing it to my attention, as it helps everyone here!
The formula for calculating amps for a 3-phase load is: Watts/(Volts x 1.732) = Amps Remember, you have to multiply the volts by the square root of 3 when calculating these 3-phase loads. Hope this helps!
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.
Most of the 15kw furnace load is due to the heat strips. The blower motor is a small fraction of that. In fact, much of the time in the field, the blower motor is not even taken into consideration because it is such a minimal load as compared to the heat strips. Remember, when taking into account the largest motor, it cannot include other loads (e.g. heat strips) - even though they are both part of the same furnace unit when it's all assembled. The reason the AC or heat pump is treated differently is because the compressor motor is by far the largest load of the unit - the opposite of a furnace. I hope that helps clear it up a little!
Yes, as long as you don't have any other larger motors elsewhere, of course. In most cases for residential, the AC or heat pump will be the largest motor load of the building - even with an electric furnace (because the heat strips are the lion's share of the load, not the motor).
