I know that we have a consensus based code, but there are parts of the code that have "scientific" research behind them. Take the following examples:
1. Who is responsible for the ampacity tables in 310.16?
2. Who decided that cooking equipment could be derated on a commercial kitchen?
3. Why are the EGC's in 250.122 sized way they are?
There has to be scientific study behind these sections, and others in the code. Taping the white conductor with black tape for the hot conductor in a romex is a good example of how the "consensus" part of the code works. I'm not saying that the examples that I mention above are not consensus based, but I do think that there is a difference between those, and 6" of free conductor, or having a green grounding conductor. Somewhere....someone....had to do the "leg work", the lab work, the testing, the this, the that, the whatever to come up with a good reason for all this stuff. I said all that to say this....besides the ROP's and the ROC's is there a source(s) of information out there to help me with some of the "why's" behind the code?

Why is there air?
Doc

lotta heads in the NEC Doc,
yet the history of the NEC has, to my knowledge, not been published.

I've often wondered myself of those who write the trade mag articles, as they must have some resource, or all be good researchers.

Case in point pg 70-143, 310.15(C), i think it may be McGrath-Neer (SP?) formula.
I read a story on how they researched captive conductor heat, assumably leading to UL standards, whis more of this was , as you say...documented...

Spark,
I just think it would be a great study. Why? Some may ask. For the knowledge, and also because when we have the reasons behind the rules, it opens up our eyes, and we reduce the chance of violating the code because we know the principals upon which it is established.

Why does the sun make your hair lighter, but your skin darker?,
Doc

Yes!

My mentor was a good one for not only saying "do this" but also "and this is why" type thing...

The "why's" definitely help one to remember the "do's"...

I've always said to myself that I would train apprentices in the same manner.

BTW: Got a young man interested in taking the test, a hard-working, bright and easy-going guy... It's getting to the point that Joe and I can't handle it all! Looks like I may finally get the chance to train someone from scratch!

Watt,
As far as grounding electrode conductors go and egcs use the same formula, It is based on a 5 second withstand rating (that is as long as any fault should last in theory), Circular mil area (from Chap 9, table 8) divided by 42.25 gives you that rating.

I keep that one on the top of my head, the ampacity tables I don't, they involve a lot more math, but basically it is from the Neher-Mcgrath, and is a compromise (it may be better to say "most often encountered) of all the conditions a cable can be placed in based on time of load, duration of load, and maximum ampacity that can be conducted for the CMA used.

Soares Grounding workbook has a lot of history of the NEC and grounding in it and can be an interesting read.

George,
Isn't part of the EGC sizing based on limiting the voltage drop on the EGC to 30 or 40 volts while the fault is being cleared?
Don

Don,
Geez don't start that. BIG bone of contention as to if that was properly considered. I think that's probably how I started with all the calcs anyway based on that very question. The NEC in the EGC area is woefully inadequate, and it's something most designers/engineers/electricians never seem to pick up on.........until it's too late anyway.

The proper answer to your question is Yes, it's supposed to be. It never seems to consider length in their calc, only cma though.

1. Tests and studies by Sam Rosch in the 1930's
2. Utilities nationwide conducted surveys which gave us many of the demand factors in the NEC.
3. Eustace Soares in the 1960's tested and calculated much of the information on equipment grounding conductors.
Suggest you join NFPA and IAEI, as a means of keeping up to date on future changes.
Creighton

Creighton,
Agreed, it is definitely Eustace Soares that did the grounding, AND an explanation of it is in the book named after him. I still feel the IAEI took a lot of the meat out of his original books that should have been kept in them.

Creighton,
have you Written anything on this in the past? It would make for an interesting discuusion here......

Gentlemen,
I know it would take volumes to cover the "science" behind the code, but it would be a great resource to have one place to go to for that kind of information. Please, realize that I'm talking about the "science" behind the entire code. I used the examples above because they were the first things that came to my mind.
Is a work of this magnetude even possible. Would anyone besides myself, and a few others on this forum want it.
So many books are written about "what the articles and sections mean", but few are written about how the articles evolved into the code that we have today.

Where am I?,
Doc

Yo Doc,
I know this sounds unholy boring, but I always thought that as a teacher, I should REfamiliarize myself with the basics at least every few years, it's just one of those REAL boring obligations I've set for myself.

But with that in mind, there are three books I rely on that start at the beginning and work your way up.

1) The American Electricians Handbook
2) Eustace Soares "Grounding and Bonding Electrical Systems for Safety" currently published by the IAEI, also available from Construction bookstore
3) Transformers by Gebert/Edwards (May not be published anymore.

I never do this marathon style, even I can't take it (and I was a history major )I read one chapter a night, sometimes even a half. Not exactly a monumental effort, but it does take a bit of consistency and dedication.

They don't go into a lot of history, but all 3 literally will begin at the bottom, and take you as far as you need to go.

Hope that's what you're looking for.

hmmm,
Doc ...you propose an interesting document, of marketable caliber, as i would surely purchase one.

I can imagine some sort of HB style, where there is the current code, and 'historical' commentary of length to follow....

one of yer better 'scrips Doc.....

Watt Dr.: What a great idea. I am working on a book already, with David E. Shapiro. I started as an apprentice in 1941 so I was around when a lot of this happened.
If any of you have additions to Watt Dr/s list it would be helpful.
Thanks.
Creighton.
PS George C. didn't we correspond a few years ago?

That does sound like an interesting topic.
How about;

Conduit fill %
360 deg. of bend
derating by # of conductors and temp.
Box fill

There must also be some science behind spacing of supports for different sizes of pvc conduit and expansion fittings.

Bill

Creighton,
We did, we did. Actually on several things a few years ago. You are probably remembering a little fight I had with a local AHJ when I was a contractor. The AHJ wanted to electrically isolate the gas pipe, and then wanted it tested to prove it was isolated.

You and Tom Henry were both kind enough to ring in for my appearance before the VA state electrical board.

We had some other correspondence on some articles I was writing, something I have not done in about 8 years. Thanks for remembering.

I agree wholeheartedly on this.

I'm always interested in why certain arrangements or requirements came about, when they were introduced, and so on.

Fricken...fracken...#@%...sassafrilliacken...If you y'all write a book and become billionares would you at least say it was "The Watt Doctor's" idea, and maybe slip me a copy of it when nobody is looking. Just send ol' poor homeless Doc some bread crums. I also agree with spark. It should be in "handbook form". Tarnation....dagnabit...I could have been an "electric star".....fricken...famuos writer....limoes...private jets...Hollywood parties...
Gentlemen, for the good of the trade, if you can use the idea, run with it.

Watt could have been?,
Doc

[This message has been edited by The Watt Doctor (edited 08-02-2002).]

ya could been a contender.....