Assuming it wasn't, do you think that would have made a difference?
If so, specifically in what way?
Harmonic affects
- Thread starter Hameedulla-Ekhlas
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If so, specifically in what way?
- Location
- Illinois
- Occupation
- retired electrician
It may as the NEC is very conservative and installations made based on Article 220 load calculations results in an electrical system that has more capacity than will ever be used in most buildings.
PowerQualityDoctor
Senior Member
- Location
- Israel
This is exactly what I am saying. Next time when you see over heating, use the Dranetz to measure harmonics. You may be surprised with the correlation. I know more than one thermographers that when they measure high temperature they recommend to perform harmonica analysis.
I agree with this statement (with some exceptions). The problem is that because of this (or other reason?) the level of maintenance is less than in Europe.
To sum up - good engineering and well maintenance prevent most of the problems. There are places with problems, including of harmonics, and it is recommended to periodically check the status. The only issue is the definition of problem - process failure is definitely a problem. I think that unnecessary low efficiency is also a problem.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
PowerQualityDoctor
Senior Member
- Location
- Israel
I did not give any knowledge, though. This will take time.
wptski
Senior Member
- Location
- Warren, MI
I believe in Europe they don't have anything like NEC or code to follow. They are required to do some testing like the use of loop testers which you can't even purchase in this country even though companies like Fluke offer them. Loop testing is required on a new home and every ten years there after.
PowerQualityDoctor
Senior Member
- Location
- Israel
There are many obligated standards by different standard organizations like IEC and EN. On top of this, there are the directives. Most of this standards are more comprehensive and more demanding than NEC.
What I said is that NEC is more conservative and the result is that the investment in infrastructure is higher, which leads to less issues. For example, the maximum voltage drop on long line is 2% according to NEC, 3% according to BS (British Standard) and 5% in Europe. This means the cross section is 2.5 larger according to NEC.
Last Leg
Member
- Location
- Houston, TX
Wow. All this has been very interesting reading. There is, however, a consideration that may not have been mentioned. Back in the mid '80's, this problem was addressed by the IEC and international standard developed by manufacturers to limit the amount of harmonics that could be put back into the electrical system by equipment. Without this, by now the systems would probably be burning like the Chicago fire.
http://www.ptsdcs.com/whitepapers/24.pdf
The sky is falling! The sky is falling!
http://www.ptsdcs.com/whitepapers/24.pdf
The sky is falling! The sky is falling!
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Nope. In general, voltage drop is not covered by the NEC. It has unenforcable recommendations as FPNs. Articles 647 and 695 are the only exceptions that I know of.
wptski
Senior Member
- Location
- Warren, MI
What I mean is that here, they follow NEC and don't look back. Here, you test a GFCI by pressing the Test Button, if it trips, it's good. Similiar RCD(?) in England must pass a trip time and current trip test using the fuctions on the loop tester I mentioned above.
brian john
Senior Member
- Location
- Leesburg, VA
it is only common sense as that is how we make a living, little more testing little more cash. GOOD BUSINESS
weressl
Esteemed Member
However some of those appear and validated in peer-reviewed scintific anc technical publications where the technical soundness is validated and commericalism is removed.
Don is right that there is a host of commercial garbage out there that was written by salespeople without ANY technical background and their claims and statements are laughable if not outright lies.
skeshesh
Senior Member
- Location
- Los Angeles, Ca
I personally think while local chapter meetings may sometimes seem like absurd advertising campaings by the big shrimp, the IEEE articles and recommendation publications are the most trustworthy. NEC itself is not immune to influence from mfg. to include regulations that can benefit their particular brand, as many of you may know.
I found this thread decently interesting, but must say that it is basically a microcosm that reflects the range of arguments that's going on in the technical community, on a national level and beyond.
I found this thread decently interesting, but must say that it is basically a microcosm that reflects the range of arguments that's going on in the technical community, on a national level and beyond.
dbuckley
Senior Member
- Location
- Canterbury, New Zealand
I cant speak for all of Europe, but can for what it used to be like in the UK.
The NEC equivalent in the UK is colloquially known as the "wiring regs", and was officially the British Standard BS 7671:2001 - Requiirements for Electrical Istallations, IEE Wiring Regulations, 16th Edition. It runs to about 300 pages, and the print is bigger than the NEC
The first such regs were published in 1882.In general, the difference between the 'Regs and the NEC is that the NEC is far more detailed and specific; the Regs, apart from a bunch of chapters about special locations (eg construction sites and swimming pools), gives you a set of principles to which one must adhere. Within the principles, the electrician is required to come up with their design.
With the NEC, no matter what is said frequently, it is a design manual; it gives very rigid constraints about almost every part of an installation.
Let me give you an example. Calculation of the maximum load of an installation. The NEC gives you chapter and verse on how to calculate loads taking some percentage of something or other. The complete 'Regs statement on calculating maximum load is (311-01-01): "The maximum demand of an installation shall be assessed. In determining the maximum demand of an installation or part thereof, diversity may be taken into account"
Thats it in its completeness. Thus the electrician is responsible for determining what the maximum demand is.
So discussions between electicians in the UK are very different than one sees on this forum. Under the NEC, the question is always "which article applies to this problem?". In the UK, the question is more like "of all the ways I could solve this problem, which one should I choose?"
The mandatory use of testers is to prove an installation. For example, there are requirements in the 'Regs that wiring cannot overheat under fault conditions, which means that the duration and magnitude of the fault current must be known, and you cant prove the maximum fault current without a earth loop impedence tester. You cant prove absence of leakage without a megger.
The NEC has some real straightjackets. SDSs are one of them, in that you're always required to bond the secondary to the system ground. In the 'Regs there is no such restriction. But you are required by the general pricniples to ensure that an installation is safe, so you cant build a shock hazard; if you choose not to ground you have to do something as an alternative to protect against shock.
Note that I am not saying one system is safer or better than the other - just that they take different approaches to the same goal - safe installations.
weressl
Esteemed Member
That sounds more like dishonest business, therefore it is eventually bad for everyone.
brian john
Senior Member
- Location
- Leesburg, VA
Actually it is called good business, the customer has a possible issue as a PROFESSIONAL electrician it is MY JOB to determine what the issue is, this involves testing of a variety of types and a harmonic survey may be ONE OF the methods a professional utilizes to identify and solve problems. AS THAT IS MY JOB.
So thanks for the compliment.
weressl
Esteemed Member
A 'professional' electrician is not qualified to perform a harmonic study. I also stay away from self-thaught brain surgeons.
mivey
Senior Member
So there you go Brian, you have been over-reaching. :grin:
I saw a Ripley's episode where some guy made his own false teeth using concrete and stuff. Ground his own teeth, drilled into his jaw, etc. Ouch!I also stay away from self-thaught brain surgeons.
I think you are ill informed, many electricians can actually teach you (yes even you) if you listen.
I also stay away from self-thaught brain surgeons.
Self-thaught? :grin:
Roger
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