harmonics/neutrals

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greg1147

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I'll try to be as brief as possible, I have a problem with harmonics in PC lab, 10/4 with oversize neutral #6. PC's have been added with individual UPS's, = harmonics. The electrical engineer wants me to rum an additional cable and use the conductors as a neutral, not in the same raceway? I am looking for the article that addresses this issue. I know it in 300 just haven't found it.
Thanks in advance.
 
300.3(B) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4).

Welcome to the forum. :)
 
Charlie,
Thanks for the info, guess I will need to keep a copy of the NEC in my tool cart. In-house is like working at the other end of the spectrum, little bit of a curve.
Greg
 
Better yet what type of issues, if the engineer wants you to viloate the NEC with the neutral issue what says he knows anything about harmonics.
 
You might also tell him that non-compliant work done by non-licensed people is just as illegal.
 
greg1147 said:
I'll try to be as brief as possible, I have a problem with harmonics in PC lab, 10/4 with oversize neutral #6. PC's have been added with individual UPS's, = harmonics. The electrical engineer wants me to rum an additional cable and use the conductors as a neutral, not in the same raceway? I am looking for the article that addresses this issue. I know it in 300 just haven't found it.
Thanks in advance.
Click to expand...

Take the electrical engineer before the board.
 
Jesse7623 said:
Take the electrical engineer before the board.
Click to expand...
Sorry, I can't agree with that action. Assuming he is a new engineer, he has the theory but not the background to do this without error. Basically he is an apprentice and the person who is training him didn't catch the error. If he has been out of school for a while, maybe he has not done this type of work very long. Basically he is an apprentice and the person who is training him didn't catch the error. Do you see where I am going?

He does need to have the error pointed out to him, in private, so he will learn. If he doesn't listen and refused to read the code, then it is time to go over his head. Don't use a sledgehammer to drive a tack. :)
 
Harmonic Mitigation

Harmonic Mitigation

There are ways to mitigate harmonics. This isn't one of them. Problem is separating those that really work from those the really don't. I'm too new to the forum to know if products can be recommended. If so, will be glad to suggest someplace to look.
 
DataCenterGuy said:
. . . I'm too new to the forum to know if products can be recommended. . .
Click to expand...
We do not have a problem of talking about products or even recommending them based on your own experience. However, we come down hard on a salesman who is hawking his line of products and we will ban a spammer in a heartbeat. :)
 
simtra

simtra

I have no problem with harmonic since using simtra. it is shielded and can be run in the same conduit with data. go to youtube and type simtra cable
 
greg1147 said:
... 10/4 with oversize neutral #6. PC's have been added with individual UPS's, = harmonics.
Click to expand...

This is 3#10's and 1#6 neutral? (assume 20A branch CB's?)
I can't realistically imagine a THD that would overpower this setup.

Buy some better quality UPS's?
Look at terminations?
 
Harmonic Mitigation - Some Recommendations

Harmonic Mitigation - Some Recommendations

Suggest you look at the following website for some thorough explanations (even though they are product oriented):

http://www.mirusinternational.com/pages/faq.html

Another good source is Power Quality International, Inc.
www.powerqualityinternational.com

In general, forget so-called "Harmonic Filters" for most situations. But if PQI were to recommend one of their special filters, after understanding the specific equipment causing your problems, you might consider trying it. In my experience, they tend to be professional in their recommedations.
 
Harmonics is one of those areas where almost all of the information on how to solve the "problem" comes from people with a vested economic interest in helping you solve the problem. Outside of full blown data centers there are very very few documented cases of harmonic caused problems.
 
Agreed - but --

Agreed - but --

I have to agree in general. The "problem" is over-marketed to sell "solutions", and that't true in Data Centers as well. However, our firm also has a substantial market in Gaming, and the lousy power supplies in electronic slot machines have also been known to create problems. With no experience in lab designs, I can't speculate whether the posed problem is real or not, but if it is, I thought I would suggest places to try.
 
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