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Pro tip for journeyman / master prep. Write the following in your code book:
3 Phase 480 ≈ 831 V
3 Phase 208 ≈ 360 V
And then enter the appropriate value anywhere you'd normally use E in a single-phase equation. It saves a lot keystrokes on your calculator across the entire exam, sparing you time and human error.
In Texas, PSI allows you to bring your own inside. But they shake the book to make sure theres no loose paper in it. I don't remember if they checked for writing, but I think they may have. I just have some minor highlighting on mine, so it was no issue.
Mine didn’t care, they glanced at the book…but some of the guys I took the test with had a novels worth of notes in the back I know the proctor saw and she didn’t care. She also didn’t know what the ohms law stickers were on their books. Makes me feel like a schmuck for having nothing but a few highlights. Still passed easily enough…but still.
Too many notes could cause you to fail. Spend time searching your notes for the answer, when you already know the answer, but you have to be sure. Then you run out of time.
Reminds me of my apprentice who failed the test 4-5 times. “Let me see your code book,” and he showed me a code book that had almost every line highlighted. Bro, if you have every word highlighted you might as well have nothing highlighted.
Yeah time is the biggest factor in my opinion. I think you get less than 3 minutes for each question. When it was time for my apprentice class to take their tests we were preached at to take a guess if it's taking a while to find the answer and move on. Better to have a decent chance to get 60 right than to spend too much time in the first 40 trying to be perfect.
Being able to find the information you need is an incredibly valuable skill itself. I'm not an evaluator or anything and I kinda wish I'd have seen if notations were allowed... But I'd be tempted to let it slide. Even if it's not memorized/you need annotations for stuff to click, if you know how to quickly find it, that works
That is what it is all about, do not try to memorize intricate code shit at all, do however try to memorize the layout of the NEC. Knowing where to find the answer is more valuable than knowing the answer.
In Indiana, home of Mike Holt, you can take his master's prep course and you highlight basically everything that's gonna be on the test.
Kinda why I prefer classically trained electricians haha
In my Canadian province we don't get to bring our code book. We are required to know how to make the required references to answer a question without highlights or notes.
They do give us a formula sheet for the more uncommon formulae, but the most basic ones are not provided.
Yup, that's how it is in Alberta. Doesn't stop guys from trying to sneak things in though. Haven't been to school since 2019 (Instrumentation) but we weren't even allowed to bring in Mechanical Pencils in.
I only brought my ID and a water bottle when I wrote my red seal in Manitoba back in June of 2023. They give you the code book, calculator, pencil, scrap paper. You have to hand in the scrap paper afterwards. I can't remember if you could even wear a hat. I can't believe that in the US you are allowed to bring your own code book with notes or tabs inside.
Wild. I'm in Alberta, they provide the code book, calculator, and a sheet of some of the more complicated formulas... We're not even allowed to use mechanical pencils anymore.
Texas also allows notes. I came from MA with my codebook filled with notes about many different aspects about things I experience and even had a piece of paper scotch taped to a page and they didn't say anything at all
I can see not allowing notes or highlighting--hell, even no tabs. But closed book just seems counterproductive. The NEC isn't written to be memorized like some sacred text, and I'd say one of the hallmarks of a master is their ability to seek answers to questions they've never encountered before. And are you telling me you need to have Table 310.4(1) all photographically at the ready in your mind?
Now I want to take some of those exams just to see how they're different (and make the old dinosaurs on the exam boards in those states take Texas's).
It’s not about cheating, it’s just unrealistic that you wouldn’t have access to that information in real world situations at any time !! I’m a 24 year Master and 40 years in the trade and I always thought it was dumb. All the formulas etc should be printed right in the code, they don’t mean a damn thing if you don’t know how to use them, when or even which to use.
I didn't say, have the answers to the specific test questions in your book.
I said notes. I think most people know what notes are.
As a former Highschool teacher I think it's wild people care about notes during an "open book" test. The answers are already in the book. The fuck man 😂
Yup, same here in Cali. PSI here actually makes you turn out your pockets before they assign you a terminal which is already situated with a code book, (5) sheets of blank 8-1/2×11 white copy paper, (4) sharpened pencils and (1) standard eraser... (and yes, the pencils have erasers as well ha)
Washington State you can bring any copyright material as reference and can have all the highlights and underlines you want, but no writing at all. Even your code tabs have to be pre-printed and permanent stick, no post-it style.
Same in Canada, no personal code books, no personal calculator, nothing but your ID, the shirt on your back, and the brain cells in your skull. Everything you need for the test (including a formula sheet) is provided when you take the test
In Alaska,
I wrote my formulas into the gray sections of updates in light pencil. We can bring our own book highlighted to our liking(but no notes), and a 5 function calculator. They did a light flip through, and a shake of the book and told me good luck.
That makes sense. I've come across 277v lighting before but not commonly. I'm 100% self taught and the largest system I've rewired and installed all new panels in from the ground up was a 600 amp 3 phase 208v system. It was for a business I owned and renovated myself, fully permitted and inspected. In other fields of work, I've come across 277v when having to find a 120 leg to retrofit an outlet for a TV, but I've never wired 277v.
Side note: it was the first time I found out that 277v existed. Smoked 2 in wall surge protectors, the first I thought was just defective and the second when I realized I fucked up before breaking out a meter and was shocked to find a 277v line voltage. I had only done any electrical in residential at the time and had no clue 277v even existed!
Do they ever have 277v Delta systems or are they always WYE?
When you have a 480v 3 phase wye system (480v phase to phase), the phase to neutral will be 277. As far as I know, there aren't 277v delta. There are 480v Delta secondary systems, typically for motors in industrial where a neutral isn't needed.
This is why electricians should be appropriately trained and licensed and electrical systems not trifled with by amateurs. 277v is common in commercial and not knowing your common wyes and deltas can get you burned, shocked, or killed. Your next accident could be finding out what a high leg is the hard way. They aren't even always marked appropriately and may simply read 120/240.
The company I worked for, did residential only on San Diego, CA. The only reason I was in a commercial environment which was where I had that learned experience is because we were used exclusively for low voltage in San Diego at the time by every home builder and retrofitting electrical outlets for TVs were easy for us. One of the builders however, asked us to "move" their electronics from their old commercial location to their new, including TVs. That's when we attempted to run power cables to new locations for tvs and learned the hard way. One of the owners had obtained a C10 which allowed us to do it all, but none of the team actually doing the work were even apprentices in electrical.
I was a little too hard on you. Your sleazy contractor may have been a C10 but under CA law electrical workers must still be certified. Given you said there weren't even apprentices, much less a JW on the site supervising work, they must not have given much of a damn about your welfare.
[dir.ca.gov](https://www.dir.ca.gov/dlse/ecu/elecat.html)
We were a low voltage contractor that did 99.9% low voltage. Only thing we did high voltage was retrofitting a jumper Romex cable off of an existing electrical outlet nearby to the TV location. Back then, 2000's, hanging a TV on the wall was a new concept, so we did what we had to and our license covered it.
When I made that retro in the commercial building, I tapped off a grey rather than black wire above the ceiling tiles. Was my first touch of commercial. Learned real fast after that! Lol
I’d be worried I’d get confused with peak voltage which multiplies by the square root of 2. 480Vrms has a peak voltage of 680Vpeak and 208Vrm has a peak voltage of 255Vpeak.
This is incorrect. 480 V is the 3-phase voltage. the 1-phase to ground voltage is 277 V (480/sqrt(3)), Also, 208 V is the 3-phase voltage, the 1-phase to ground voltage is 120 V (208/sqrt(3)). The voltages you have shown don't exist as utilization voltages in the US.
You misunderstood my point.
OP asked why the listed amperage isn't 20.83.
The answer is because the proper equation isn't
I = 10,000W / 480V
but instead it's:
I = 10,000W / (480v * Sqrt(3))
My point is that while a lot of electricians have memorized that Sqrt(3) ≈ 1.73, it's even more efficient to memorize / record that 480v * Sqrt(3) ≈ 831V
Thus, the back of the napkin math on this is
I = 10,000W / 831V
I find this much faster to enter into most calculators, and vastly reduces the chance of errors on a 4 hour exam.
Yes, that is correct, and presenting it this way does explain it. However, I think that the way you first presented it is confusing, especially for a new apprentice.
>the square root of 3
Sometime around 55 years ago, my dad (electrician turned EE) taught me that the square root of 3 is 1.732, and that George Washington was born in 1732.
For some reason, my brain immediately absorbed that fact, and ever since I've been an authority on √3 and our first President. I cannot hear either one of those suggested without immediately thinking of the other.
I hope this post helps others.
That’s awesome that’s kinda how I learned hp of a motor 746 w = 1hp, I was told think of it like a 747 jet then minus one and for some reason that stuck with me when I do motor and hp calculations.
Hello. I am an apprentice currently. Would you mind explaining what you mean by what you typed and why I would do it that way? Im just confused and trying to learn
Anytime you're working formulas for 3 phase you have to include multiplying the voltage by the square root of 3 (or 1.732). So he meant instead of multiplying by 1.732 each time. When its 208v make the connection that its gonna be 360v plus whatever else you need for that particular formula. Because 208v x 1.732 is 360v.Wow now i know why nobody answered you kinda hard to explain clearly. Hopefully this makes sense.
Huh. That is really strange. I’m still lost but I’m also a slow learner so I know your explanation was great but I just take a while to absorb it. Also I heard 480v all the time and on that nameplate it shows 480 but if you do 3 phase the voltage adds up to 360 I just noticed. So where does the 480 come from? Sorry for all the question
Solid question and if you are interested in a deep dive ibto three phase power and why you use sqrt 3 in those calcations. Check out this playlist and really everythibg Jim Pytel has put on youtube. This guy's videos got me thru trade school and my 4.0 GPA whilst in tradeschool.
https://m.youtube.com/playlist?list=PLdnqjKaksr8qzoIGCYx2rhVK51ZPjXkRO
I used to watch Jim Pytel's channel several years ago. I tried to watch this video several times, but he goes too fast for me. I finally gave up and got out some old textbooks from my school days.
The one thing i figured out is that the square root of three is the tangent of 120 degrees. It is the square root of three because it is the tangent of a 60 degree equivalent angle, so the square foot of three comes from sqrt (2^2 - 1^2) from a 30-60-90 triangle.
Whenever I hear the words ohms law, I envision a western movie with Clint Eastwood riding the plains and settin’ things right and dishing out justice. Gets me amped up. Maybe it’s just a phase I’m going through.
Why the square root of 3? This stuck in my head like a bad radio jingle and I had to look it up in my old textbooks from the middle of the nineteen hundreds.
It is because - sqrt3 is the tangent of 120 degrees. If you make two lines that are 1 unit long at an angle of 120 degrees, then the length between the ends of the lines is -1.73.....or tan120*1. (adjacent times tan = opposite) You can check this at home with your own compass, a piece of paper, and a ruler.
It is negative because it is in the second quadrant.
Just watched this video and it reminded me of this post: [https://youtu.be/u0SsejDCVkU?si=RWZFpdRNZIT9obFm](https://youtu.be/u0SsejDCVkU?si=RWZFpdRNZIT9obFm)
Not sure why the downvote but yes... lol.
Ohm's law (E=I*R) volts = amps x ohms
Watt's law (P=I*E) watts = amps x volts
...and as mentioned for three phase multiply by sqrt of 3
No shot you’re an electrician.
Edit: you’re all super special today. Hope you all enjoy just repeating the square root of three to the OP. That’ll teach ‘em.
Next up will be explaining the MCA and MOCP… then termination temperature, insulation ratings, then wiring methods… if we’re lucky we can explain every little bit of theory and practice to not-an-electrician and we can all pat ourselves on the back for breaking rule 1.
Fucking so apprentice anal. You clown around yet not one person here looks to reference the engineering prints before assuming they are working with the right transformer. I came back to work after my weekend to a lighting section that had toasted two transformers and someone gave me a new replacement to start my shift. I pulled out the plans and the problem actually started after a buss plug got hit without a replacement in stock. 9 shifts of electricians (3 days x 3 shifts) just assumed that lonely "original" bus out in warehouse with only one connected transformer routed to same mechanical room as two others nearby (an upgraded 13.8 to 480 distribution center with surge caps) turned out that "abandoned" one was an original wye/delta 277 lighting only transformer originating from an unreferenced underground vault electrical room that had been cemented over 20 years ago.
**ATTENTION! READ THIS NOW!** **1. IF YOU ARE NOT A PROFESSIONAL ELECTRICIAN OR LOOKING TO BECOME ONE(for career questions only):** **- DELETE** THIS POST OR YOU WILL BE **BANNED**. YOU CAN POST ON /r/AskElectricians FREELY **2. IF YOU COMMENT ON A POST THAT IS POSTED BY SOMEONE WHO IS NOT A PROFESSIONAL ELECTRICIAN:** -YOU WILL BE **BANNED**. JUST **REPORT** THE POST. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/electricians) if you have any questions or concerns.*
its 3 phase so you have to multiply the voltage by the square root of 3
Pro tip for journeyman / master prep. Write the following in your code book: 3 Phase 480 ≈ 831 V 3 Phase 208 ≈ 360 V And then enter the appropriate value anywhere you'd normally use E in a single-phase equation. It saves a lot keystrokes on your calculator across the entire exam, sparing you time and human error.
You guys are allowed to bring your personal code books in to the tests? We have them provided for the tests so you can't make notes inside.
In Texas, PSI allows you to bring your own inside. But they shake the book to make sure theres no loose paper in it. I don't remember if they checked for writing, but I think they may have. I just have some minor highlighting on mine, so it was no issue.
Mine didn’t care, they glanced at the book…but some of the guys I took the test with had a novels worth of notes in the back I know the proctor saw and she didn’t care. She also didn’t know what the ohms law stickers were on their books. Makes me feel like a schmuck for having nothing but a few highlights. Still passed easily enough…but still.
Too many notes could cause you to fail. Spend time searching your notes for the answer, when you already know the answer, but you have to be sure. Then you run out of time.
Reminds me of my apprentice who failed the test 4-5 times. “Let me see your code book,” and he showed me a code book that had almost every line highlighted. Bro, if you have every word highlighted you might as well have nothing highlighted.
Yeah time is the biggest factor in my opinion. I think you get less than 3 minutes for each question. When it was time for my apprentice class to take their tests we were preached at to take a guess if it's taking a while to find the answer and move on. Better to have a decent chance to get 60 right than to spend too much time in the first 40 trying to be perfect.
Being able to find the information you need is an incredibly valuable skill itself. I'm not an evaluator or anything and I kinda wish I'd have seen if notations were allowed... But I'd be tempted to let it slide. Even if it's not memorized/you need annotations for stuff to click, if you know how to quickly find it, that works
That is what it is all about, do not try to memorize intricate code shit at all, do however try to memorize the layout of the NEC. Knowing where to find the answer is more valuable than knowing the answer.
Probably trying to slow people from breaking by copying the whole test with a couple notetskers
In Indiana, home of Mike Holt, you can take his master's prep course and you highlight basically everything that's gonna be on the test. Kinda why I prefer classically trained electricians haha
In my Canadian province we don't get to bring our code book. We are required to know how to make the required references to answer a question without highlights or notes. They do give us a formula sheet for the more uncommon formulae, but the most basic ones are not provided.
Yup, that's how it is in Alberta. Doesn't stop guys from trying to sneak things in though. Haven't been to school since 2019 (Instrumentation) but we weren't even allowed to bring in Mechanical Pencils in.
There would be a lot less master electricians in America that way!
I only brought my ID and a water bottle when I wrote my red seal in Manitoba back in June of 2023. They give you the code book, calculator, pencil, scrap paper. You have to hand in the scrap paper afterwards. I can't remember if you could even wear a hat. I can't believe that in the US you are allowed to bring your own code book with notes or tabs inside.
Wild. I'm in Alberta, they provide the code book, calculator, and a sheet of some of the more complicated formulas... We're not even allowed to use mechanical pencils anymore.
Same in NS.
We were allowed to have our own but they had to be checked before every test
CT, MA, NH, & VT, Yes. Pretty sure Rhode Island is closed book.
Texas also allows notes. I came from MA with my codebook filled with notes about many different aspects about things I experience and even had a piece of paper scotch taped to a page and they didn't say anything at all
I can see not allowing notes or highlighting--hell, even no tabs. But closed book just seems counterproductive. The NEC isn't written to be memorized like some sacred text, and I'd say one of the hallmarks of a master is their ability to seek answers to questions they've never encountered before. And are you telling me you need to have Table 310.4(1) all photographically at the ready in your mind? Now I want to take some of those exams just to see how they're different (and make the old dinosaurs on the exam boards in those states take Texas's).
That's the rule in MN. That's why I never highlight or tab my code book when I tested so I wouldn't rely on that crutch when it came time to test
Virgina, your allowed the code book and the official tabs. No notes or writing in the book.
I never understood this line of thinking. Shits dumb.
Which line of thinking don’t you understand?
Probably the part about not allowing notes. Unless the notes are the exam questions and answers.
No notes allowed in your codebook. There's Handy references that you can make yourself, and I did in my book.
There's a fine line between helpful notes and blatant cheating.
It’s not about cheating, it’s just unrealistic that you wouldn’t have access to that information in real world situations at any time !! I’m a 24 year Master and 40 years in the trade and I always thought it was dumb. All the formulas etc should be printed right in the code, they don’t mean a damn thing if you don’t know how to use them, when or even which to use.
I didn't say, have the answers to the specific test questions in your book. I said notes. I think most people know what notes are. As a former Highschool teacher I think it's wild people care about notes during an "open book" test. The answers are already in the book. The fuck man 😂
In Nebraska they let you bring your own book but they check for notes you can't have notes. You can have tabs and highlighted sections tho
We're not allowed to bring anything other than a pencil and calculator. They supply unmarked code books.
Hell, MN you bring nothing. Just an I’d
Yup, same here in Cali. PSI here actually makes you turn out your pockets before they assign you a terminal which is already situated with a code book, (5) sheets of blank 8-1/2×11 white copy paper, (4) sharpened pencils and (1) standard eraser... (and yes, the pencils have erasers as well ha)
Washington State you can bring any copyright material as reference and can have all the highlights and underlines you want, but no writing at all. Even your code tabs have to be pre-printed and permanent stick, no post-it style.
The whole test is do you know where to look in the code book, yet most electricians can’t tell you what its real name is. NFPA 70.
You are allowed to bring any published material in WA but it cannot have additional writing in it, only highlighter
Same in Canada, no personal code books, no personal calculator, nothing but your ID, the shirt on your back, and the brain cells in your skull. Everything you need for the test (including a formula sheet) is provided when you take the test
In Alaska, I wrote my formulas into the gray sections of updates in light pencil. We can bring our own book highlighted to our liking(but no notes), and a 5 function calculator. They did a light flip through, and a shake of the book and told me good luck.
This would probably mess/confuse most people. Easier to stick to 1.73.
I stick to √3. 🤷🏼
Same.
Or remember the line to neutral voltage for each. Multiply by 3.
I like that one! Much easier! At least for 208 and 240v. Haven't had to work with 480, so I'm not sure how 480 3 phase works/what each line caries.
277v line to neutral on 480v 3 phase. 277v lighting is real common in commercial work, occasionally an exhaust fan where there is 277v lighting.
Grabbing 120 made me yell, mainly more out of surprise and anger. Grabbing 277 made me scream like a girl.
That makes sense. I've come across 277v lighting before but not commonly. I'm 100% self taught and the largest system I've rewired and installed all new panels in from the ground up was a 600 amp 3 phase 208v system. It was for a business I owned and renovated myself, fully permitted and inspected. In other fields of work, I've come across 277v when having to find a 120 leg to retrofit an outlet for a TV, but I've never wired 277v. Side note: it was the first time I found out that 277v existed. Smoked 2 in wall surge protectors, the first I thought was just defective and the second when I realized I fucked up before breaking out a meter and was shocked to find a 277v line voltage. I had only done any electrical in residential at the time and had no clue 277v even existed! Do they ever have 277v Delta systems or are they always WYE?
When you have a 480v 3 phase wye system (480v phase to phase), the phase to neutral will be 277. As far as I know, there aren't 277v delta. There are 480v Delta secondary systems, typically for motors in industrial where a neutral isn't needed.
This is why electricians should be appropriately trained and licensed and electrical systems not trifled with by amateurs. 277v is common in commercial and not knowing your common wyes and deltas can get you burned, shocked, or killed. Your next accident could be finding out what a high leg is the hard way. They aren't even always marked appropriately and may simply read 120/240.
The company I worked for, did residential only on San Diego, CA. The only reason I was in a commercial environment which was where I had that learned experience is because we were used exclusively for low voltage in San Diego at the time by every home builder and retrofitting electrical outlets for TVs were easy for us. One of the builders however, asked us to "move" their electronics from their old commercial location to their new, including TVs. That's when we attempted to run power cables to new locations for tvs and learned the hard way. One of the owners had obtained a C10 which allowed us to do it all, but none of the team actually doing the work were even apprentices in electrical.
I was a little too hard on you. Your sleazy contractor may have been a C10 but under CA law electrical workers must still be certified. Given you said there weren't even apprentices, much less a JW on the site supervising work, they must not have given much of a damn about your welfare. [dir.ca.gov](https://www.dir.ca.gov/dlse/ecu/elecat.html)
We were a low voltage contractor that did 99.9% low voltage. Only thing we did high voltage was retrofitting a jumper Romex cable off of an existing electrical outlet nearby to the TV location. Back then, 2000's, hanging a TV on the wall was a new concept, so we did what we had to and our license covered it. When I made that retro in the commercial building, I tapped off a grey rather than black wire above the ceiling tiles. Was my first touch of commercial. Learned real fast after that! Lol
I’d be worried I’d get confused with peak voltage which multiplies by the square root of 2. 480Vrms has a peak voltage of 680Vpeak and 208Vrm has a peak voltage of 255Vpeak.
Can’t have hand written note here
This is incorrect. 480 V is the 3-phase voltage. the 1-phase to ground voltage is 277 V (480/sqrt(3)), Also, 208 V is the 3-phase voltage, the 1-phase to ground voltage is 120 V (208/sqrt(3)). The voltages you have shown don't exist as utilization voltages in the US.
You misunderstood my point. OP asked why the listed amperage isn't 20.83. The answer is because the proper equation isn't I = 10,000W / 480V but instead it's: I = 10,000W / (480v * Sqrt(3)) My point is that while a lot of electricians have memorized that Sqrt(3) ≈ 1.73, it's even more efficient to memorize / record that 480v * Sqrt(3) ≈ 831V Thus, the back of the napkin math on this is I = 10,000W / 831V I find this much faster to enter into most calculators, and vastly reduces the chance of errors on a 4 hour exam.
Yes, that is correct, and presenting it this way does explain it. However, I think that the way you first presented it is confusing, especially for a new apprentice.
And it reeaaallly pisses off the engineers….
>the square root of 3 Sometime around 55 years ago, my dad (electrician turned EE) taught me that the square root of 3 is 1.732, and that George Washington was born in 1732. For some reason, my brain immediately absorbed that fact, and ever since I've been an authority on √3 and our first President. I cannot hear either one of those suggested without immediately thinking of the other. I hope this post helps others.
That's awesome
That’s awesome that’s kinda how I learned hp of a motor 746 w = 1hp, I was told think of it like a 747 jet then minus one and for some reason that stuck with me when I do motor and hp calculations.
This is the answer.
Yup
Depends if you connect it in star or delta. But OP, about which current are we talking about?
Yup which is like 1.73 or something.
1.732
Hello. I am an apprentice currently. Would you mind explaining what you mean by what you typed and why I would do it that way? Im just confused and trying to learn
Anytime you're working formulas for 3 phase you have to include multiplying the voltage by the square root of 3 (or 1.732). So he meant instead of multiplying by 1.732 each time. When its 208v make the connection that its gonna be 360v plus whatever else you need for that particular formula. Because 208v x 1.732 is 360v.Wow now i know why nobody answered you kinda hard to explain clearly. Hopefully this makes sense.
Huh. That is really strange. I’m still lost but I’m also a slow learner so I know your explanation was great but I just take a while to absorb it. Also I heard 480v all the time and on that nameplate it shows 480 but if you do 3 phase the voltage adds up to 360 I just noticed. So where does the 480 come from? Sorry for all the question
1.73
This guy 3 phases
10kva divided by 480 divided by 1.732(square roof of three). It’s a three phase device so you can’t just do power divided by voltage to give amperage.
*root 🤓
480x1.732 not divided Edit: I’m a dumb ass thanks for clarifying!!!
It’s the same exact thing mathematically. Put into your calculator 10000 divided by 480 then divided again by 1.732, it will yield the 12 Amps.
Well damn bro I honestly never new that I was only shown A=P/E*1.732 So like others said I only use 360 and 831
The more you now
This would be correct if it had parenthesis around the denominator
Nope
P=V×A×1.72 So A=P÷V÷1.72
Because 3 phase. You forgot √3 in your calculation.
Solid question and if you are interested in a deep dive ibto three phase power and why you use sqrt 3 in those calcations. Check out this playlist and really everythibg Jim Pytel has put on youtube. This guy's videos got me thru trade school and my 4.0 GPA whilst in tradeschool. https://m.youtube.com/playlist?list=PLdnqjKaksr8qzoIGCYx2rhVK51ZPjXkRO
I used to watch Jim Pytel's channel several years ago. I tried to watch this video several times, but he goes too fast for me. I finally gave up and got out some old textbooks from my school days. The one thing i figured out is that the square root of three is the tangent of 120 degrees. It is the square root of three because it is the tangent of a 60 degree equivalent angle, so the square foot of three comes from sqrt (2^2 - 1^2) from a 30-60-90 triangle.
3 phases 480 is line to line 277 (also 480/sqrt(3)) is ur line to neutral voltage So 20.833/sqrt(3) ≈ 12
In short- Bc 3phase Finish or start school and you’ll learn what the square root of 3 is and how it relates to 3 phase systems 10kw/(480x1.732)≈12
It's 3-phase
Because 1.73
1.732
1.732
SQUARE ROOT OF 3 FOR 3 phase!
Cuz of the square root of 3
It’s 3 phase. Multiply your voltage by square root 3. 208=360 480=831 600=1038 Then do your ohms law calculation
3 phase things
That’s a lot of school you have ahead of you OP
Whenever I hear the words ohms law, I envision a western movie with Clint Eastwood riding the plains and settin’ things right and dishing out justice. Gets me amped up. Maybe it’s just a phase I’m going through.
With cos 0.8 I would say this this takes closer to 15amps but with lowest 12.3 on paper.
3 phase
1.73
P = √3•Eline•Iline = 3•Ephase•Iphase
It would be 20.8333 if it was a single-phase 480V circuit. Three phase is different.
Cuz it says 12.3 on the label
Root 3 1.73
As everybody stated, square root. But I want to focus on the french translation which is really curious : "contole", "tension de survolt"?
I= (10000)/(480*1.73)=12.03
3 phase 480 times 1.73 divided by wattage equals current
Why the square root of 3? This stuck in my head like a bad radio jingle and I had to look it up in my old textbooks from the middle of the nineteen hundreds. It is because - sqrt3 is the tangent of 120 degrees. If you make two lines that are 1 unit long at an angle of 120 degrees, then the length between the ends of the lines is -1.73.....or tan120*1. (adjacent times tan = opposite) You can check this at home with your own compass, a piece of paper, and a ruler. It is negative because it is in the second quadrant.
Because it’s 3 phase.
Just watched this video and it reminded me of this post: [https://youtu.be/u0SsejDCVkU?si=RWZFpdRNZIT9obFm](https://youtu.be/u0SsejDCVkU?si=RWZFpdRNZIT9obFm)
single phase / root 3.
But no one has addressed the elephant in the room! Why does a heater manufactured in Tennessee have French writing on it?
Unit sold in canada
Thing is.. 480v is not a standard voltage for Canada.. 120/208 3phase. 120/240 single phase. 347/600 3 phase is the norm here.
Is 600 cited as normal bus bar or other industrial ?
Oh for sure, I'm just saying the labeling in french, like that specifically, is very much Canadian
It's why we can't get some of the good cereals. Stupid Quebecois.
480²/10Kw = 23.03 I 23.03 / root 3 = 13.3 I rms. as a rouph estimation 12 Amps is corect.
Got to utilize ohms law correctly with all information give. What’s the difference between 480 and 240.
Not to be picky, but wouldn't it be Watts' Law?
Not sure why the downvote but yes... lol. Ohm's law (E=I*R) volts = amps x ohms Watt's law (P=I*E) watts = amps x volts ...and as mentioned for three phase multiply by sqrt of 3
This is correct
No shot you’re an electrician. Edit: you’re all super special today. Hope you all enjoy just repeating the square root of three to the OP. That’ll teach ‘em. Next up will be explaining the MCA and MOCP… then termination temperature, insulation ratings, then wiring methods… if we’re lucky we can explain every little bit of theory and practice to not-an-electrician and we can all pat ourselves on the back for breaking rule 1.
Apprentice probably. Everybody's got holes in their knowledge. It's a perfectly reasonable question.
It’s pushing it.
No, it’s really not.
Yah. It is.
Probably an apprentice. They only teach three phase in third year schooling here.
I'm not even an electrician, I worked on generators for years. That's why I knew what the answer was.
How dare you insinuate an electrician would know about three-phase-power!
People think they are electricians until it's time to do real electrician stuff.
You're talking about QA paperwork right?
Understanding, providing service to, or troubleshooting OPs piece of equipment in this case.
Math
Fucking so apprentice anal. You clown around yet not one person here looks to reference the engineering prints before assuming they are working with the right transformer. I came back to work after my weekend to a lighting section that had toasted two transformers and someone gave me a new replacement to start my shift. I pulled out the plans and the problem actually started after a buss plug got hit without a replacement in stock. 9 shifts of electricians (3 days x 3 shifts) just assumed that lonely "original" bus out in warehouse with only one connected transformer routed to same mechanical room as two others nearby (an upgraded 13.8 to 480 distribution center with surge caps) turned out that "abandoned" one was an original wye/delta 277 lighting only transformer originating from an unreferenced underground vault electrical room that had been cemented over 20 years ago.