Formulas in the NEC Code Book

[vermathrax]

I'm in fourth year electrical school and I have a question: Does anyone know why the formulas for voltage drop, motors, The Wire Wheel, and transformer calculations are not in the NEC Code Book? Does anyone else feel it's a good idea to have these somewhere in the code book? The only answer I've ever recieved, is we should know them by heart before we take the Journeymans Exam. I'm just wondering, since these are so important, why are they not present in the code book.

Thanks in advance for all responses!

 

[bikeindy]

Got a pen? Write um in. Its a code book not a math book.

 

[bob]

Does anyone else feel it's a good idea to have these somewhere in the code book?

The information you are asking for is used in designing the system. The code book is not a design manual.

 

[iwire]

Re: Formulas in the NEC Code Book

Does anyone know why the formulas for voltage drop, motors, The Wire Wheel, and transformer calculations are not in the NEC Code Book?

Yes........well, I think I know.

90.1 Purpose.

(C) Intention. This Code is not intended as a design specification or an instruction manual for untrained persons.

That aside I recommend doing what bikeindy suggested, write the things you want into the blank pages.

 

[bdarnell]

Re: Formulas in the NEC Code Book

That aside I recommend doing what bikeindy suggested, write the things you want into the blank pages.

I agree. Only one note of caution: Most testing agencies won't let you have handwritten notes in your book during a test. You might consider putting them in there with sticky notes so you can peel them out prior to the test.

 

[Pierre C Belarge]

One of my favorite sayings is from Einstein. Someone asked him a question and his answer was, I will have to look it up. His famous quote is:
" I never memorize what I can look up"

I agree with that, hence I do not agree we need to memorize any of those formulas when we can write them down somewhere to look up.
Write them in your book somewhere, so when you will need them, you will be able to look them up.


In reality how often does the average electrician use formulas for calculations on the job? Not too often... but if they were written down somewhere, they may use them more often.

 

[colosparker]

In reality how often does the average electrician use formulas for calculations on the job?

Everyday. Wire sizing, motor overload sizing, pipe fill, box fill, wireway fill, branch circuit, feeder, service calculations and most importantly paycheck calculations, to name just a few.

 

[peter]

I think it would be a good idea to have another appendix with some of the formulas listed. It would make the Code book more useful and would actually be a selling point.
In fact, the real question should be: what formulas should be included?
For one, Ohm's law show be included. It is obviously enforceable.
Also that complicated formula for the current on the neutral of a three phase system. How can you memorize the square root of A times B plus B times C minus whatever?? [See I haven't yet memorized it ]
Also the formulas for resistance and capacitance in parallel and series circuits. These do show up on tests and it would be a plus point to have this available in black and white during a test and even at home or at work.
These formulas are not an instruction manual but rather bits of easily forgotten/confused but vital aspects of the practice of electricians. And, I repeat, these are enforcible. After all, the Code is a law book [with all it obfuscation and legalese, and the inspector can easily issue you a red for violating Kirscoff's law.
~Peter

 

[iwire]

In reality how often does the average electrician use formulas for calculations on the job?

Everyday. Wire sizing, motor overload sizing, pipe fill, box fill, wireway fill, branch circuit, feeder, service calculations

In reality it is the minority of electricians that need to do any of that on a regular basis.

 

[iwire]

For one, Ohm's law show be included. It is obviously enforceable.

Can you explain?

These formulas are not an instruction manual but rather bits of easily forgotten/confused but vital aspects of the practice of electricians. And, I repeat, these are enforcible. After all, the Code is a law book [with all it obfuscation and legalese, and the inspector can easily issue you a red for violating Kirscoff's law.

Peter what section is cited for violating Kirchoff's law?

Is it even possible to violate Kirchoff's law?

 

[Pierre C Belarge]

The reason I posted the last sentence in my earlier post is the "reality" of the situation in the field. I will not speak for the rest of the country, but in NY the use of calculations on the actual jobsite is almost nonexistant. The size of pipe, pipe fill, box sizes (most are plastic now), sizing the conductors, transformer sizes, house calculations, service size, all of what may be a normal days calculations is the "dreaded" math that the average electrician shys away from and ... guesses at based on the past experience passed down from who they learned from.


I did a class about 3 years ago with a group of electricians, they all were installing the equipment ground conductor the same size as the phase conductor. When I showed them table 250.122, they almost kissed my....

That is the "reality" that I am speaking about!!!

 

[peter]

Iwire,
Currently, Kirschoff's law is not part of the Code book. That is why you can't find it. And that is why it must be placed in the next edition -- so that inspectors can enforce it. :wink:
And the same goes for Ohm's law. There are lots of laws on the books and they get broken all the time. But nobody seems to disobey Ohm's law.
But, back to my proposal, what formulas should be included in the new appendix G?
~Peter

 

[celtic]

In reality how often does the average electrician use formulas for calculations on the job?

Everyday. Wire sizing, motor overload sizing, pipe fill, box fill, wireway fill, branch circuit, feeder, service calculations and most importantly paycheck calculations, to name just a few.

See, we (at this forum) are ABOVE average :lol:

 

[bikeindy]

X = -b + or - the square root of b squared - 4ac all over 2a

had to memorize that in freshman algabra the quadratic formula. don't think I ever used it. ohms law is easy to memorize. but i agree that there is no reason to memorize them notbooks are good and other methods of having important formulas with you. I keep the code book in my van so when some wise ass contractor asks me if that is code I can let him look it up and tell me. I don't like the new 2005 book mine turned pink from the sun.

 

[George Stolz]

But nobody seems to disobey Ohm's law.

:lol:

But, back to my proposal, what formulas should be included in the new appendix G?

I'm all for it. Half the crap in the annexes is not very useful anyway, so adding some things I can use from time to time would be a great idea.

In Colorado, all the notes I write in my code book would be to no avail, they require us to use their code book and only permit us to carry in a very basic calculator.

According to my friend who just took his master, they don't even allow us to bring our own pencils anymore. Someone with way too much time on their hands cheated by cutting some sort of notch code into their pencils to remember the formula. I'm pretty sure by the time the guy memorized his pencils, he probably had the formulas memorized anyway. :roll: :lol:

I don't like the new 2005 book mine turned pink from the sun.

You allow your book to sit in the sun? Heretic! Mine sits under a little umbrella with a pillow and a guilded mat to lay upon...

 

[iwire]

Heck why not include the instructions to cut in a panel?

Or how to cut an old work into plaster and lathe?

How about an annex that is dedicated to conduit bending?

Another annex explaining how the permitting and inspection process in each area that the NEC is used?

NO WAY!

I am entirely against turning a code book into a instruction manual.

A cop enforces the law, would you expect a law book to have instructions about gun cleaning?

 

[vermathrax]

I really dont think we need every aspect of our jobs in the code book.however all things that are on the electrical exam should be there.

if i need a formula to solve a problem that is on the test ( and that i would use in the field, even if it is only once and awhile,) i should be able to look it up in the code book somewhere. Im not suggesting we put things in it just so we can say that they are there. Im saying there should be an annex just for formulas that are on the test. if its not related to a question that might be on the journeymans or the masters exam,or something we might use in the field, then it should not be in there.


I just wonder if so many people feel the same way,then why are the individuals who make the code book so adamant about them not being in there? are they afraid that people might be able to pass the tests? :shock:

 

[George Stolz]

Bob,

How is an annex devoted to frequently used formulas debasing the Code to a design manual?

So, you're in favor of deleting Annex C? I find it a handy reference for finding conduit fill in a hurry.

Throw Ohm's Law at someone not involved in this industry, and they will not be much farther ahead than if you don't.

695 has requirements for voltage drop. Wouldn't it be nice to see the NFPA's preferred method of determining voltage drop, even if in unenforceable Annex text?

I don't understand your position on this topic.

 

[iwire]

I don't understand your position on this topic.

You don't?

I thought I made my opinion abundantly clear. :lol:

How is an annex devoted to frequently used formulas debasing the Code to a design manual?

I would not say formulas make it a design manual, IMO including formulas would make it an instruction manual for untrained persons

A rule book is a rule book.

An instruction manual is an instruction manual.

They need to be kept separate.

So, you're in favor of deleting Annex C? .

I would not miss it.

695 has requirements for voltage drop. Wouldn't it be nice to see the NFPA's preferred method of determining voltage drop, even if in unenforceable Annex text?

No it would not be (IMO).

If they (the NFPA) have a way they want it figured it should be included in 695 other than that your moving into an instruction manual.

If you go and buy Major League Baseballs rule book will it teach you how to hit or catch?

No...it is a rule book not an instruction manual.

Bob

 

[iwire]

I really dont think we need every aspect of our jobs in the code book.however all things that are on the electrical exam should be there.

All that says to me is your not ready to take the test.

I just wonder if so many people feel the same way,then why are the individuals who make the code book so adamant about them not being in there? are they afraid that people might be able to pass the tests? :shock:

Maybe it's that they want the test to be a test not a gimme.

IMO, The harder the tests the better for the trade, less electricians means higher wages.

Don't take any of this personally it is just my opinion.

I don't like the idea of making it easer to get the license.