Do electrical engineers fully understand the purpose of the NEC?

Are they aware of the NEC installation rules and safety requirements?

Do they receive any training on the NEC?

Can they become licensed as an electrical contractor with their credentials?

Joe this is a hard one to answer since today electrical engineer has such a broad meaning. In my job I have meant electrical engineers that specialize in various sections of the electrical field for example may be an expert with Programmable controllers and servo drive systems but know very little of residential, commercial or industrial electrical systems except as they pertain to their area of specialty. I have also interviewed numerous Entry level E.E. from college and in my opinion feel they do not concentrate on the core electrical field or had any training on the NEC or OSHA for that matter. This is not true in all cases but based on my experience. When I bring a new Electrical Engineer in I expect them to work at least some amount of time with the plant electricians on new installations as well as maintenance. This would include High voltage distribution systems and learn the importance of proper PPE. It can not be expressed enough no matter where electrical work is performed that one be familiar or know how to use the NEC and by the same token be familiar with OSHA regulations if they have people working for them.

Jerry E.E. Manager

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

Most electrical engineers don't work in power distribution so I'd say no, most don't know or even get involved with any NED issues.

And at elast in NJ, an EE can get his electrician's license. I think it requires an accredited EE degree plus 1 year relevent experience plus passing the state exam.

would'nt people involved in design loose interest with a document including discalimers against design.

I received no training on the NEC or OSHA while in school. Coming from designing Ultrasonic Sensors (pate4nts pending and all sorts of other garbage) into this field about 14 years ago, I barely knew who UL was though I was familiar with Fatory Mutual.

I commend you Jerry for getting your new EE's working in the field. My first week in this job was with an electrician (whom I was to oversee and had some 30 years in the field) rebuilding sewage lift stations. I learned alot from him in the 2 years before he retired.

I hope that all of us EE's take one of my professors creeds to heart that a college degree shows that one is capable of learning and that your learning should be life long.
I have been very greatful for the state and IAEI training that I have attended.

The other thing that I hope is that no one ever fears to take me to task. I may be hard headed and have to have something proved to me, but I will listen and I am teachable (ask my wife she has the system worked out so I think it is my idea).

My nephew is currently in an EE field up at school and it will be no different for him when he graduates except I am trying to give him some broader experience. After I retire in about 15 years, I am looking seriously at teaching part time and maybe will fill a gap on the side. The emeritis professor who taught our power class (note: only one class) still was hitting only the theory and design of devices (motors, etc.) not transmission or the NEC.

Shane (P.E.)

Joe,
You have asked a very broad question. Your question is similar to asking if all electricians that install low voltage residential alarms circuits, if they aware of the NEC installation rules and safety requirements regarding commercial work? or if they receive any training on the NEC? In most situations the answer is no.

Electrical engineers that design power related installations are aware of the NEC installation rules and safety requirements, and receive training on the NEC, or they are under the direction of an engineer that does so. New engineers do not have the benifit of an engineering apprentiship programs like many electricians would for installations, and endure many years of on the job training, similar to electricians, except in more controlled conditions (in an office or pulled aside at a job site). Generally we learn by having a senior engineer instruct us on a project by project basis, or screw up (this appears to be the best way that I have learned, since I do it often, and try not to repeat the mistake!)

joe...(Do they receive any training on the NEC?)

joe.i remember years ago i was working with a helper that wanted to be in the electrical field for a year before becoming an electrical engineer.the last thing i remember is i sent him down to the basement for a pipe stretcher. about .15 min later he came back up and said he could not find it.so i told him to check by the tripod.and he did.by then i was in tears.yea,he went on to be a engineer

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

as an engineer, i know that we don't always understand the Nec and its principals.
i didn't receive any training on the nec in college.
in tennessee, we must take a state test to get your license, unless you were grandfathered in.

joe....this brings to mind a situation several years ago, when i was working for another employer who was helping do the electrical installations in the (then) new Honda auto plant. they had a crew of e.e.'s under contract to install the robot welders and material handlers, and all the electronics that go with them. i had the audacity to ask one of them why they were insisting on setting a particular control panel in a certain location, that it was going to be extremely difficult, and costly, to pipe it and wire it, according to "code". he just looked at me like, "who the hell are you, questioning my decisions?", then told me that it was my problem, not his. ....sorry to say, that left a really bitter taste in my mouth.

gramps

No, I don't believe that ALL EE's understand the code, nor do I believe that ALL electricians understand the code, nor do I believe that ALL AHJ's understand the code.
Rowdy

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).]

Joe,
The issues that you have addressed should be well known by most qualified electricians,the guys that get the work done.Yes I agree the good engineer should be familiar with them as well(your example of raceway fill was excellent) but his job is to use science and physical principles/equations to predict the results and then test to see if they are achieved.
Chris

It would seem that in order to come to a solution, you will need to provide some more information about the loads, conductors and how they are served. It is possible that the solution is not to pull a parallel neutral, but to mitigate the harmonic problem at the load, change the distribution groupings or determine a malfuntioning load. A parallel neutral is a band-aid solution and shouldn't be entered lightly.

oh, and please don't beat up the engineers. Don't be surprised that the next time you look in Section 16050 of your specification, that it doesn't say that you have to bring donuts any time the engineer shows up.

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

Under engineering s ....upervision

So then these words should be ignored or deleted?

I am not beating up on engineers.

I only asked a simple question, and it seemed to rattle many cages. If you look throughout the NEC there are many rules that require an engineer. See Article 505 for one example.


Here are the rules where engineering supervision is required:

(2) Supervised Installations. For supervised installations, branch-circuit conductor sizing shall be permitted to be determined by qualified persons under engineering supervision.

Supervised installations are defined as those portions of a facility where all of the following conditions are met:

(1) Conditions of design and installation are provided under engineering supervision.

(3) Supervised Installations.

For supervised installations, feeder conductor sizing shall be permitted to be determined by qualified persons under engineering supervision. Supervised installations are defined as those portions of a facility where all of the following conditions are met:

(1) Conditions of design and installation are provided under engineering supervision.

(1) Conditions of maintenance and engineering supervision ensure that only qualified persons monitor and service the system.

(3) The conductors shall be considered to be protected if calculations, made under engineering supervision, determine that the system overcurrent devices will protect the conductors within recognized time vs. current limits for all short-circuit and ground-fault conditions.

(4) Conductors shall be considered to be protected if calculations, made under engineering supervision, determine that the system overcurrent devices will protect the conductors from overload conditions.

(A) Location and Type of Protection.

Feeder and branch-circuit conductors shall have overcurrent protection in each ungrounded conductor located at the point where the conductor receives its supply or at an alternative location in the circuit when designed under engineering supervision that includes but is not limited to considering the appropriate fault studies and time–current coordination analysis of the protective devices and the conductor damage curves.

The overcurrent protection shall be permitted to be provided by either 240.100(A)(1) or (A)(2).

Exception: In industrial and commercial premises under engineering supervision, it shall be permissible to size the ampacity of the neutral conductor to not less than 20 percent of the ampacity of the phase conductor.

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.

(1) Tables or Engineering Supervision. Ampacities for conductors shall be permitted to be determined by tables or under engineering supervision, as provided in 310.15(B) and (C).

(C) Engineering Supervision. Under engineering supervision, conductor ampacities shall be permitted to be calculated by means of the following general formula:

(B) Ampacities of Conductors Rated 2001 to 35,000 Volts. Ampacities for solid dielectric-insulated conductors shall be permitted to be determined by tables or under engineering supervision, as provided in 310.60(C) and (D).

(D) Engineering Supervision. Under engineering supervision, conductor ampacities shall be permitted to be calculated by means of the following general formula:

Exception: Where electric enclosures covered by Part IV of this article are part of an industrial wiring system operating under conditions of maintenance and supervision that ensure only qualified persons monitor and supervise the system, they shall be permitted to be designed and installed in accordance with appropriate engineering practice.

If required by the authority having jurisdiction, design documentation shall be provided.

Manholes, vaults, and their means of access shall be designed under qualified engineering supervision and shall withstand all loads likely to be imposed on the structures.

Exception No. 1: Where the setting specified in Table 430.52 is not sufficient for the starting current of the motor, the setting of an instantaneous trip circuit breaker shall be permitted to be increased but shall in no case exceed 1300 percent of the motor full-load current for other than Design E motors or Design B energy efficient motors and no more than 1700 percent of full-load motor current for Design E motors or Design B energy efficient motors.

Trip settings above 800 percent for other than Design E motors or Design B energy efficient motors and above 1100 percent for Design E motors or Design B energy efficient motors shall be permitted where the need has been demonstrated by engineering evaluation. In such cases, it shall not be necessary to first apply an instantaneous-trip circuit breaker at 800 percent or 1100 percent.

(3) Evidence acceptable to the authority having jurisdiction such as a manufacturer’s self-evaluation or an owner’s engineering judgment.

A flexible cord shall be permitted for connection between portable lighting equipment or other portable utilization equipment and the fixed portion of their supply circuit.

Flexible cord shall also be permitted for that portion of the circuit where the fixed wiring methods of 501.4(A) cannot provide the necessary degree of movement for fixed and mobile electrical utilization equipment, in an industrial establishment where conditions of maintenance and engineering supervision ensure that only qualified persons install and service the installation, and the flexible cord is protected by location or by a suitable guard from damage.

The length of the flexible cord shall be continuous. Where flexible cords are used, the cords shall be as follows:


(3) Evidence acceptable to the authority having jurisdiction such as a manufacturer's self-evaluation or an owner's engineering judgment

A flexible cord shall be permitted for connection between portable lighting equipment or other portable utilization equipment and the fixed portion of their supply circuit.

Flexible cord shall also be permitted for that portion of the circuit where the fixed wiring methods of 505.15(B) cannot provide the necessary degree of movement for fixed and mobile electrical utilization equipment, in an industrial establishment where conditions of maintenance and engineering supervision ensure that only qualified persons install and service the installation, and the flexible cord is protected by location or by a suitable guard from damage.

The length of the flexible cord shall be continuous. Where flexible cords are used, the cords shall be as follows:

Exception: Sequential delayed automatic connection to the alternate power source to prevent overloading the generator shall be permitted where engineering studies indicate it is necessary.

(3) Engineered Systems. For an electric vehicle supply equipment ventilation system designed by a person qualified to perform such calculations as an integral part of a building’s total ventilation system, the minimum ventilation requirements shall be permitted to be determined per calculations specified in the engineering study.

This annex provides application information for ampacities calculated under engineering supervision.

Most of us seem to be confused here.

Electrical design is based on physical laws.

The NEC is a set of perscriptive rules that approximate the physical laws. These rules will be sufficient under most circumstances. The NEC points out some circumstances where the rules may not be sufficient.

An engineered design will be based on the physical laws and the specific circumstances. An engineered design will always be sufficient.

-----

With regard to the neutral problem. An engineer can make a decision that the NEC fill/derating rules are too conservative and another neutral can be pulled without derating the condutors.

For course this incurs the rath of the AHJ who thinks the NEC is to be followed. A lot of yelling follows. A few people land in jail and the hospital and then the lawyers go to work.

-

I should point out the most engineers prefer to use perscriptive rules that cover their area of practice better than the NEC covers their area of practice.

Engineers do a good job at their work.

I work for a large engineering/construction company. All of our engineers in a supervisory role are registered, and most are Master Electricians. We do engineering and design for many of the major Fortune 500 companies, and many who are not in that category. We all have to know the NEC and how to apply its various rules. Most of the young engineers just out of college don't yet know the NEC, but are getting a few lessons in learning. All that I work with have been given the instructions to get registered (as an engineer) and to pass the Journeymens and Masters exams. I worked with one engineer that told me the Masters exam was harder than the PE. Maybe she was just smart. But she is actually a good engineer, and could probably teach the NEC.
Like some of the other posters here on this board, I feel the NEC could be written in a more understandable down to earth language to make it more readily applicable. However, I just don't see that happening any time soon. Its people like Joe, Mike Holt, Charlie Trout, and a few others that make the NEC understandable. My thanks go to these and others around the country who dedicate themselves to the safe use of electricity.
Just my 2 cents worth.

Thanks for all of your replies!



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