ECN Forum Forums General Topics of the Trade General Discussion Area Do All Electrical Engineers Understand the NEC?

Joe,

I'm in my twenty fifth year as a sole proprietor Electrical Contractor one person business. I also have a Bachelors in EE. My formal EE education included nary a word from the NEC. My formal life as an electrician did not include training until the State of Minnesota started requiring continuing education only eight years ago.

I think it is a fair to expand your original to: Do electrical engineers or electricians fully understand the purpose of the NEC?

I'm an engineer for an Electrical Contractor and I don't know all of the intricate details of the NEC. If I'm stumped on a certain Code section, I'll ask a few of the Senior Electricans. However, I believe that Engineers should be out in the field more often with the Electricans to see the problems encountered and the solutions being implemented.

The NEC itself could be written MUCH easier than it is now.

Joe,
I received my BSEE in 1960 and received no training in the NEC until I took a refresher course for my PE license in the early 1970s.It was then I became aware of the importance and purpose of the NEC.Prior to that I was a RF transmitter/receiver designer for Microwave systems and had no reason to be interested in the NEC.When I took the PE exam in Florida there were several references to the NEC on the exam.
I continued on with RF design until 1999,retired and realized I could receive an Electrical Contractors license(if I passed the state exam)in the state of Florida with my PE license and was allowed to sit for the EC exam.With the help of Mike Holts crash course I passed and got my license.The only NEC I knew at that time was what Mike taught in his course and what I remembered from my PE studies.I have since worked with a few EC/Master Electricans that taught me the practical aspects.
ECN has been a valuable part of my continuing education in the EC and NEC world.
Chris

OK here's the question:

Existing raceway with 4 wires and grounded conductor is suffering because of high harmonic neutral currents.

How does the engineer apply the following exception to 310.4

Exception No. 4: Under engineering supervision, grounded neutral conductors in sizes 2 AWG and larger shall be permitted to be run in parallel for existing installations.

FPN:Exception No. 4 can be used to alleviate overheating of neutral conductors in existing installations due to high content of triplen harmonic currents.

EEs don't need to know the NEC unless they work in the power field or they design and install of heavy industrial equipment. Many EEs don't do that type of work, instead they work in fields from radio frequency use to integrated chip design to consumer electronics design.

Unless they need to know the NEC as part of their jobs, many EEs won't know it.

MacWire

My wife's 1st cousin is an ee.He designssome type of robotics systems. He has been a student of the code to varying degrees over the years.But he says that in 27 years at his job he's never used the nec.

[This message has been edited by ga.sparky56 (edited 02-12-2003).]

Joe,

I would say that quite a few Power EE Interns learn the NEC from the numerous and multiple plan check revisions
they have to correct and submit!!!



Sorry, but this is not only my most personal irritant, but could very well be the way some Power Systems Design EEs
learn how to design, specify and calculate a project, which will conform to at least the NEC!

It's really a joke to see 3+ successive revisions listed on a set (in the "Delta" call-outs and within the title block).

Throw in CEC / CBC and City / County Of Los Angeles Codes to really see the Revisions lists rise!!!


I am saying this because a lot of the plansets I see now, and have seen since the beginning of 1990's, are simply
disclaimers and very minimal EE work!!! All items listed for specs and page notes are just Xref documents from
some other client's project!
Seen too many general notes and specs for Bank Branch T.I.s where the notes mentioned things related to either a
Residential project, or maybe a Liquor Store!

Note # 5: Electrical Contractor Will Provide And Install 320 Volt 4 phase 3 wire outlet for Beer Cooler. Consult
With Budweiser Rep. (Vendor) for exact location

That's no joke!!! Seen it before!!! (although I over exaggerated the voltage and phase stuff!)

Seeing this stuff pushes me even more to produce the most accurate, complete and properly Engineered planets that I
can!

BTW, Have seen a few really good jobs done by EEs and Architects over the past 5 years; just wish there was
more!

Just like Non-Compliant issues get Joe's blood boiling, this stuff gets under my skin like a Tattoo!!

Scott35 S.E.T.

[This message has been edited by Scott35 (edited 02-13-2003).]

Scott35,

I agree with you about the revisions. One revision thru plan check should be enough. We have a running checklist for the two most notorius: City of LA and City of Long Beach. These guys know their Code and are by the book!

Joe,
I don't understand why the NEC requires engineering supervision to apply this exception 4.It looks like a straight forward thing to do,parallel the neutral conductors for #2 or larger to relieve the heating effects of the neutral due to harmonic currents.
It would require testing,IMO, after the new conductor(s)is placed in parallel to see if the desired effect(lowering of temp and voltage drop) is achived.Maybe that is what the NEC is getting at????
Chris

OK:

The engineer would have to be familiar with the raceway fill 40% Table 1, Chapter 9 requirements, and if the neutral was replaced with two neutrals of the same size, would that existing raceway be large enough, and would the existing raceway (one found in Annex C) be adequate for the additional wire?

PS: Don't try to feed a snake into the existing raceway because it will get stuck on the tape the installer did not remove when the first feeder was installed.

This means that the 4 wire feeder would have to be pulled out an back in with 5 wires.

Oh! and what about the 110.14 rule related to more than one wire under a lug...

Just some stuff, and to date have not ever received any reply to this question from an engineer.

[This message has been edited by Joe Tedesco (edited 02-12-2003).]