# what is "clean power" and "dirty power"?



## kbsparky (Sep 20, 2007)

"dirty" power has a lot of "noise" in it -- surges, sags, sine wave distortions, etc. Many electronic items (including newer ballasts) can't handle dirty power for very long without failure.


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## McClary’s Electrical (Feb 21, 2009)

btr said:


> I have been in the trade for a few years and still learning, so bare with me.. I have heard many different terms in the field, but clean and dirty power are new to me. What does it mean on a commercial job site and what does it refer to? Im thinking ac/dc, transformer, etc.... Im drawing a blank. I know its not solar, wind, etc. Can you tell me what it means?
> 
> Thanks


 


See the wave form in my avatar? That is a perfect 60 cycle wave form and perfectly clean power. If it were powering something that was causing distortion or harmonics, you would see it on the oscilloscope as really erratic instead of smooth, that's dirty power.

Some triac dimmers chop off the front half of a wave form, some chop off the back half of a wave form, although not what I would consider "dirty power" it is certainlty not ideal, and can damage fan controllers in ceiling fans.


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## MaintenanceGeek (May 18, 2010)

*I agree*

Kbsparky is most correct it is not a good condition to have. Ends up with lost of issues and is quite harmful


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## jredwood301 (Feb 8, 2009)

dirty power can be cleaned up with the use of capacitors, in case you wanted to know.


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## btr (Aug 29, 2010)

Ill try to be a little clearer. 

Im on a job site running seperate conduit runs for "clean power" and "dirty power". Although i dont know what they mean Im pretending to understand... Im at a new company and trying to understand the lingo from my new foreman/co-workers. At this time I dont need to terminate any wires, just continue the EMT runs so, I wont ask what the terms mean.. yet..

anything?


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## 480sparky (Sep 20, 2007)

Clean "Pure" sine wave:








​
"Dirty" sine wave:








​


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## ohmontherange (May 7, 2008)

It sound like one run is " conditioned power" probably from a UPS, The other run is not. Just a guess.


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## jredwood301 (Feb 8, 2009)

Dont pretend to understand something you dont know, this is the wrong trade to act like a smart guy by not asking. Their is two many things that can HURT you. Their is nothing wrong with asking questions it shows you care about your career and want to learn. Dont be that guy that always screws things up on the job because his ego is to big to ask questions.

good luck


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## Magnettica (Jan 23, 2007)

jredwood301 said:


> Dont pretend to understand something you dont know, this is the wrong trade to act like a smart guy by not asking. Their is two many things that can HURT you. Their is nothing wrong with asking questions it shows you care about your career and want to learn. Dont be that guy that always screws things up on the job because his ego is to big to ask questions.
> 
> good luck


:thumbsup:


Welcome to ET!


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## brian john (Mar 11, 2007)

The terms are relative to the end user, anything that effects your operation. If it doesn't effect your facility there is no issue.

Often (quite often) the power is blamed for anything that goes wrong and the term "dirty power" gets thrown at all issues that in reality are hardware or software problems.


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## mattsilkwood (Sep 21, 2008)

Most likely what they are talking about is "dirty" power is used for receptacles or lighting.

Your "clean" power is an IG circuit, A neutral and a ground for each circuit Instead of sharing a neutral for every 3 circuits and 1 ground per pipe. This will be used for point of sale equipment and computer loads. 
Some of the ones I've done you can share a neutral, some you can't. It just depends on how it is speced.


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## Vintage Sounds (Oct 23, 2009)

Speaking of clean power, has anyone ever worked with something like this ?


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## brian john (Mar 11, 2007)

mattsilkwood said:


> Most likely what they are talking about is "dirty" power is used for receptacles or lighting.
> 
> Your "clean" power is an IG circuit, A neutral and a ground for each circuit Instead of sharing a neutral for every 3 circuits and 1 ground per pipe. This will be used for point of sale equipment and computer loads.
> Some of the ones I've done you can share a neutral, some you can't. It just depends on how it is speced.


IG has nothing to do with whether or not a branch circuit can provide usable power to equipment, other than to waste copper.

NOW spec's are something different if the customer wants it for some who doo voo doo electrical engineering, they pay for it they get it.


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## mattsilkwood (Sep 21, 2008)

brian john said:


> Often (quite often) the power is blamed for anything that goes wrong and the term "dirty power" gets thrown at all issues that in reality are hardware or software problems.


 It's always a power issue when equipment doesn't work right.
That or a gorund rod.:laughing:


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## brian john (Mar 11, 2007)

mattsilkwood said:


> it's always a power issue when equipment doesn't work right.
> That or a gorund rod.:laughing:


true......................


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## Magnettica (Jan 23, 2007)

Are harmonic currents known as "dirty power"?

And is the fix for this dirty power a super (oversized) neutral? 

I've always thought that dirty power was power that created electrical noise.


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## mattsilkwood (Sep 21, 2008)

brian john said:


> IG has nothing to do with whether or not a branch circuit can provide usable power to equipment, other than to waste copper.
> 
> NOW spec's are something different if the customer wants it for some who doo voo doo electrical engineering, they pay for it they get it.


 I know that and you know that, but it amazes me how many engineers don't. 
Like you said, if they want to pay for it I'm more than happy to run twice the pipe and pull more wire in.:thumbsup:

The OP said commercial so I bet this is what he is talking about. If he was industrial I would lean more towards an isolation transformer or reactor.


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## Skipp (May 23, 2010)

Clean power has its own transformer (K-factor or an non-linear type). A clean power panel (which is nothing more than a regular panel with a 200% rated neutral). And if its true clean power it will have one neutral for one circuit (no neutral sharing). Non linear loads (switching power supplies, electronic ballast..etc.) cause harmonic distortion, mostly on the odd numbered harmonics. 
Most affected is the 120/208Y system. Single phase 120/240 does not seem to have the same harmonic distortion problem.


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## brian john (Mar 11, 2007)

mattsilkwood said:


> I know that and you know that, but it amazes me how many engineers don't.
> Like you said, if they want to pay for it I'm more than happy to run twice the pipe and pull more wire in.:thumbsup:
> 
> The OP said commercial so I bet this is what he is talking about. If he was industrial I would lean more towards an isolation transformer or reactor.


Hey I have seen numerous ground rods driven outside office buildings for a PQ issue on the 12th floor of a high rise.


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## mattsilkwood (Sep 21, 2008)

brian john said:


> Hey I have seen numerous ground rods driven outside office buildings for a PQ issue on the 12th floor of a high rise.


 I had an Italian tell me the reason his machine wouldn't run was because it needed a ground rod at the machine. It took me all day to tell him why that wasn't the issue. His english was just about as good as my Italian.
It turned out he had made a bad solder joint.:whistling2:


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## micromind (Aug 11, 2007)

mattsilkwood said:


> I had an Italian tell me the reason his machine wouldn't run was because it needed a ground rod at the machine. It took me all day to tell him why that wasn't the issue. His english was just about as good as my Italian.
> It turned out he had made a bad solder joint.:whistling2:


If he used a 40 watt light bulb to determine the effectiveness of the ground rod, I've worked with him!!

I'm not making this up.....to determine if the ground rod was any good or not, he connected one wire of a socket with a 40 watt bulb in it to the ground rod, the other wire to 120AC. If it lit brightly, it was good. If not, then it wasn't.


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## brian john (Mar 11, 2007)

Skipp said:


> Clean power has its own transformer (K-factor or an non-linear type). A clean power panel (which is nothing more than a regular panel with a 200% rated neutral). And if its true clean power it will have one neutral for one circuit (no neutral sharing). Non linear loads (switching power supplies, electronic ballast..etc.) cause harmonic distortion, mostly on the odd numbered harmonics.
> Most affected is the 120/208Y system. Single phase 120/240 does not seem to have the same harmonic distortion problem.


Not not necessarily true, that may be some engineers solution to trying to obtain "clean" power, but if the equipment causing the power issues is fed from your xmfr, 200% pnl, oversized neutral, the "dirt" is still there. The fix for a PQ issue depends on what the issue is.

The most common source of poor power quality are neutrals grounded down stream from the main N-G bond, the fix for this is clearing the short(s).

Single phase does have harmonic issues, but they do not have triplen harmonics, that is additive issues that result in possible overloaded neutrals.

In 30 years of doing PQ issues, and 100's maybe 1000's of investigations, I have only seen a handful of problems with harmonics. Typically the issue is not when the system is fed from the utility but when the source is a standby generator.

Most of the issues with harmonics when fed from the utility were in the really days of electronics, PC's, VFD's, with overloaded transformers.

To my knowledge (old memory) I cannot remember ever having neutral issues with any lighting panels.


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## Bob Badger (Apr 19, 2009)

btr said:


> Ill try to be a little clearer.
> 
> Im on a job site running seperate conduit runs for "clean power" and "dirty power". Although i dont know what they mean Im pretending to understand... Im at a new company and trying to understand the lingo from my new foreman/co-workers. At this time I dont need to terminate any wires, just continue the EMT runs so, I wont ask what the terms mean.. yet..
> 
> anything?


No official meaning as far as I know.

Most of the jobs I work we have 'clean' and 'dirty' power.

The dirty will come from any panel with any other type of equipment connected to that panel as well.

The clean may come from just another panel with only similar loads or may the panel maybe supplied by a simple isolation transformer or it may be supplied via a UPS system etc. It all depends on what the engineer is looking for.


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## Skipp (May 23, 2010)

brian john said:


> Not not necessarily true, that may be some engineers solution to trying to obtain "clean" power, but if the equipment causing the power issues is fed from your xmfr, 200% pnl, oversized neutral, the "dirt" is still there. The fix for a PQ issue depends on what the issue is.


 
Of course any equipment causing power issues on the load side of transformer will defeat the purpose of "clean" power. Thats why you segregate the loads. 

You are correct however about the fix being dependent on type of PQ issue. I was not considering the other issues such as spikes, surges, sags...etc. 
I remember when a local high school retrofitted all the T12's with T8's. Thats when the problems started. The grounding conductor had massive current on it. And these new ballast were failing months after install. Sometimes 30 ballast in one day. Then one of the computer labs fried all the surge protectors within seconds. One after another the SPD's started popping (capacitors exploding) and smoking.


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## kbsparky (Sep 20, 2007)

Skipp said:


> ...I remember when a local high school retrofitted all the T12's with T8's. Thats when the problems started. The grounding conductor had massive current on it. And these new ballast were failing months after install. Sometimes 30 ballast in one day. Then one of the computer labs fried all the surge protectors within seconds. One after another the SPD's started popping (capacitors exploding) and smoking....


Which proves the point that the latest and greatest "electronic" gadgets are not always what they are cracked up to be. 

Any energy savings they may have realized has been eaten up by increased maintenance and replacement costs as they learned the hard way in this instance.


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## RIVETER (Sep 26, 2009)

Over time,in my years here at Ford people have blamed a lot of malfunctions on dirty power. That I know of we just keep building cars and nothing changes. I don't know what is is. I think about the hetrodyning of different frequencies... if the offending frequencies have enough power to affect each other, I can see the possibility of creating circuits that would eliminate certain problem cycles.


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## SparkYZ (Jan 20, 2010)

btr said:


> Ill try to be a little clearer.
> 
> Im on a job site running seperate conduit runs for "clean power" and "dirty power". Although i dont know what they mean Im pretending to understand... Im at a new company and trying to understand the lingo from my new foreman/co-workers. At this time I dont need to terminate any wires, just continue the EMT runs so, I wont ask what the terms mean.. yet..
> 
> anything?


I've worked on 12 or so Wal-Mart remodels, and they spec out in the plans that normal power, and isolated ground circuits do not share any raceways or junction boxes. We use the slang dirty and clean power for this instance. 

This may be what you are dealing with, as the two types of circuits require separate conduits.


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## brian john (Mar 11, 2007)

btr said:


> I have been in the trade for a few years and still learning, so bare with me.. I have heard many different terms in the field, but clean and dirty power are new to me. What does it mean on a commercial job site and what does it refer to? Im thinking ac/dc, transformer, etc.... Im drawing a blank. I know its not solar, wind, etc. Can you tell me what it means?
> 
> Thanks


As these terms are not defined in IEEE Dictionary of Standard Terms I would bet your foreman has only his interpretation, as you can see from this thread there is no REAL consensus as it means different things to different people.

Myself I NEVER USE the terms, clean power or dirty power when discussing power quality (PQ) with customers. Though I have seen the terms (mostly "clean ") utilized on drawings. But often the engineers do not know what they are discussing only what they hope to achieve which is a project with no equipment operational issues, to achieve this they try a variety of installation practices many that have worked in the past and there fore they utilize again. Not because of sound engineering but because the practice SEEMED to work. 

I say seemed to work because there may not have been any issues to begin with. As noted many engineers spec IG circuits, there is NO evidence that IG buys anything in the field of PQ. It is a good practice for electricians as it increases work and job cost, but for PQ there is NO advantage. As a matter of fact most IGs systems I have seen are not NEC compliant or introduce more issues than they are suppose to solve or leave the system with un-grounded circuits or result in multiple grounds on the neutral or, or, or................



> This may be what you are dealing with, as the two types of circuits require separate conduits.


They do not require separate conduits, except if sepc.'d or based on conduit fill.


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## SparkYZ (Jan 20, 2010)

brian john said:


> As these terms are not defined in IEEE Dictionary of Standard Terms I would bet your foreman has only his interpretation, as you can see from this thread there is no REAL consensus as it means different things to different people.
> 
> Myself I NEVER USE the terms, clean power or dirty power when discussing power quality (PQ) with customers. Though I have seen the terms (mostly "clean ") utilized on drawings. But often the engineers do not know what they are discussing only what they hope to achieve which is a project with no equipment operational issues, to achieve this they try a variety of installation practices many that have worked in the past and there fore they utilize again. Not because of sound engineering but because the practice SEEMED to work.
> 
> ...


On these jobs, it is spec'd out. I know its not an NEC requirement.


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## Lighting Retro (Aug 1, 2009)

Wait, so is this like the difference between Republican and Democrat?


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## wildleg (Apr 12, 2009)

no, it's more like the difference between politicians with their clothes on, and politicians with their clothes off.


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## goose134 (Nov 12, 2007)

Round here clean and dirty get thrown around all the time. Clean is always the IG panels or 200% neutral panels. Makes people feel better that their power is supposedly clean. Dirty will be used for convienience receptacles and non-computer items. As has been pointed out, it in no way mitigates PQ issues.


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## micromind (Aug 11, 2007)

I think the whole 'clean power, dirty power' thing was invented by engineers so they could look like they actually knew something, plus it drove the cost of a job up, thus more money for them. 

Rob


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## goose134 (Nov 12, 2007)

I had a conversation recently with Steve Albini who owns an unbelievable recording studio here in Chicago. He was telling me about a problem they were having with an unwanted noise in their system that was showing up in the recordings. He has a chemical ground, isolation trannys, the works. His tech assistant rigs up a portable amp, headphones and antenna and walks the neighborhood. On and off for two years he is pinpointing the source of the noise. He finds out that there is a copier with a bad power supply in the third floor of an office 6 blocks away. Electrical Audio even footed the bill to have them fix it. Sounded more like an RF problem, but still best troubleshooting story I've heard in a while.


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## Jlarson (Jun 28, 2009)

Clean power you can use right away, dirty power you have to clean with a power washer first.




















:jester:


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## B4T (Feb 10, 2009)

A few years ago they were building an electronics plant and the towns were all trying to land the huge building for property tax purposes.

When the manufacture.. SYMBOL TECHNOLOGY at the time, pick the parcel to build, they cited it was picked because of a "huge abundance of clean power".

It was built next to a LIPA sub-station and that was the "clean power"


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## Jlarson (Jun 28, 2009)

brian john said:


> As noted many engineers spec IG circuits, there is NO evidence that IG buys anything in the field of PQ.


When I see an orange IG outlet I think "The 80's called they want their useless outlet back."



mattsilkwood said:


> I had an Italian tell me the reason his machine wouldn't run was because it needed a ground rod at the machine. It took me all day to tell him why that wasn't the issue. His english was just about as good as my Italian.
> It turned out he had made a bad solder joint.:whistling2:


Why is the answer to every CNC problem a ground rod? Someone suggested that fix on another non electrical forum and I posted about 1/4 page of :laughing: in response and I think all I did was offend people.


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## brian john (Mar 11, 2007)

There are power quality issues, usually related to improper grounding, something harmonics, sometimes voltage drop. But the amount of money spent on equipment to mitigate these issues would be better spent on proper engineered installations.


Transients can be devastating to electronic equipment, hell to distribution equipment if the magnitude and duration are sufficient.


This does not mean data centers and the like do not need to spend money for UPS, to minimize primarily from power outages and sags.


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## Mr. Sparkle (Jan 27, 2009)

Lighting Retro said:


> Wait, so is this like the difference between Republican and Democrat?





wildleg said:


> no, it's more like the difference between politicians with their clothes on, and politicians with their clothes off.


I'd say it's more like the difference between the young spry eager kid choosing to go into politics because he wants to better the world around him and the middle aged burned out guilt free greedy lawyer that is in politics because he gets perks off the common mans back.


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## Mr. Sparkle (Jan 27, 2009)

goose134 said:


> I had a conversation recently with Steve Albini who owns an unbelievable recording studio here in Chicago. He was telling me about a problem they were having with an unwanted noise in their system that was showing up in the recordings. He has a chemical ground, isolation trannys, the works. His tech assistant rigs up a portable amp, headphones and antenna and walks the neighborhood. On and off for two years he is pinpointing the source of the noise. He finds out that there is a copier with a bad power supply in the third floor of an office 6 blocks away. Electrical Audio even footed the bill to have them fix it. Sounded more like an RF problem, but still best troubleshooting story I've heard in a while.


Steve Albini is the man. :thumbsup:

Tell him some random guy on a forum said thanks for all the great music recordings, especially the one from Failure.

Sorry for thread derailment........


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## wildleg (Apr 12, 2009)

this is dirty power


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## RIVETER (Sep 26, 2009)

That is exactly what I am talking about. You must keep your mind on your work. You'll never catch me looking at one of those videos. When at work I am very intense and just want to get the job done. No time for that garbage. When I was younger I could have been tempted to stray and watch but, even then, I would only watch until my arm got tired.


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## Electric_Light (Apr 6, 2010)

Skipp said:


> Non linear loads (switching power supplies, electronic ballast..etc.) cause harmonic distortion, mostly on the odd numbered harmonics.
> Most affected is the 120/208Y system. Single phase 120/240 does not seem to have the same harmonic distortion problem.


That's because of the way its used. 

HVAC and lighting are the big loads in commercial buildings. 
Elevators, a/c, vents. run on 480v. smaller units on 208v. lighting in big bldgs are 277v. 

Then, what else is there? 120v plug-in stuff. Those represent majority of loads on 208/120 system and these days, they're office equipment. Unlike electronic ballasts, computers usually don't have any harmonic corrections. Very recently, harmonics correction at each device was mandated in Europe though.

Single phase 120/240 in resi. powers everything, so the percentage of IT equipment relative to total load is small.

Dirty has a lot to do with rate of change. Computers are rated to operated on 90(Japan -10%) to 264v(EU+10%) these days. So, you could take a variac and sweep it slowly between 100-140v and it won't flinch. That doesn't mean that power supply can respond quick enough if you're running it on generator power at 140v and you start a big motor on it and it abruptly dips to 90v.


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## JRaef (Mar 23, 2009)

Oops


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## gnuuser (Jan 13, 2013)

Electric_Light said:


> Dirty has a lot to do with rate of change. Computers are rated to operated on 90(Japan -10%) to 264v(EU+10%) these days. So, you could take a variac and sweep it slowly between 100-140v and it won't flinch. That doesn't mean that power supply can respond quick enough if you're running it on generator power at 140v and you start a big motor on it and it abruptly dips to 90v.


correct in an industrial or commercial environment with three phase motors and single phase motors you can find a tremendous amount and wide variety of electrical noise due to motors and heating equipment cycling off and on.
the same can be said in residential 

its widely recommended to install large ups/and or power conditioning, to protect electronics. even with these precautions we often have to install noise filtering near the equipment we want to protect. 

sound engineering and proper installation can alleviate most of the problems. but no amount of special hardware can protect you from poorly designed installations.

most of us know this and are quick to point out possible issues.
quite often its the ones we are pointing it out to that choose to listen or not to.


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## Semi-Ret Electrician (Nov 10, 2011)

In the good ole days, as gnuuser pointed out, isolation transformers were always recommended by VSD mfrs. Their six step sine waves were said to create "dirty power".

MSW inverters, I know have claimed many sophicated electronics including my Milwaukee battery charger. They even stated it was a no-no in their operating manual, which I forgot to read.


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## Electric_Light (Apr 6, 2010)

gnuuser said:


> correct in an industrial or commercial environment with three phase motors and single phase motors you can find a tremendous amount and wide variety of electrical noise due to motors and heating equipment cycling off and on.
> the same can be said in residential


It is common everywhere. If the frequency is right, a cyclical fluctuation will cause enough noticeable flicker to generate complaints, but IT equipment are unaffected. An this case study, an industrial welding machine's duty cycle coincided with visibly annoying flicker. 
http://dranetz.com/case-studies/service-area-flicker



> its widely recommended to install large ups/and or power conditioning, to protect electronics. even with these precautions we often have to install noise filtering near the equipment we want to protect.


To alleviate a concern like the one addressed in that case study, you will have to eliminate it at source, place light bulbs on regulated power supply such as double conversion UPS or PoCo intervention.



> sound engineering and proper installation can alleviate most of the problems. but no amount of special hardware can protect you from poorly designed installations.
> 
> most of us know this and are quick to point out possible issues.
> quite often its the ones we are pointing it out to that choose to listen or not to.


Consumers will rage at PoCo suggesting them to buy a $600 double conversion UPS for light bulbs. PoCo will then tell the industrial customer that they're causing PQ issues and they need to fix it.

However, if mitigation proves extremely costly, the party who have to foot the bill may show significant resistance. Industrial customer that's affecting the network will argue through their attorney to try to avoid a very costly demand unless the PoCo can prove their process violates service agreement. 

PoCo wouldn't want to invest in infrastructure like putting that industrial customer on a dedicated transmission level to 12470v transformer to avoid complaints from customer downstream of existing 12470 network and will try to weasel out unless the service provided falls outside of acceptable guidelines. 

However, if enough residential customers complain and it goes wild on the news and industrial firm suspect public relations nightmare could exceed the cost of making changes to satisfy community demand, the changes magically get done.

Coming up with a technically sound solution is just an early step. "Who's paying for it?" is the greater barrier.

Here's another PQ related case: 
http://www.energy.ca.gov/process/pubs/san_spr96_v6n2_nl106615.pdf


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## wildleg (Apr 12, 2009)

this is dirty power


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## John Valdes (May 17, 2007)

To bad we are as addicted to coal as we are to oil.


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## Big John (May 23, 2010)

I immediately get suspicious when I hear someone say "dirty power" it's in the same category as "bad ground" for universal reasons why everything isn't working as it should.

Dealing a plant right now that had a very serious event that tripped the protection on their main incoming. It's obvious there were very high currents present, but we've got a competitor who did a study and is now blaming "dirty power" and "harmonics". Harmonics may be present, but they definitely weren't responsible for an instantaneous trip and blown fuses.


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## Bobby_Sardells (Jul 11, 2012)

dirty power can be neutral backfeeds, 3rd+ harmonics, surges, transients, which result in unwanted current in your line which results in a low power factor (more $$ for the end user)

This is usually caused by non-isolated computer circuits, ****ty ballasts, high inductance loads (motors). If you are wiring a big office it is always good to use an isolation transformer to feed the server and computer circuits.


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## Bobby_Sardells (Jul 11, 2012)

Big John said:


> I immediately get suspicious when I hear someone say "dirty power" it's in the same category as "bad ground" for universal reasons why everything isn't working as it should.
> 
> Dealing a plant right now that had a very serious event that tripped the protection on their main incoming. It's obvious there were very high currents present, but we've got a competitor who did a study and is now blaming "dirty power" and "harmonics". Harmonics may be present, but they definitely weren't responsible for an instantaneous trip and blown fuses.


If the plant is not properly coordinated, a simple short can trip the main!


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## ohmontherange (May 7, 2008)

wildleg said:


> this is dirty power


When the levee breaks...


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