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In Reply to: RE: Using capacitors across the AC posted by Tweaker456 on August 05, 2016 at 15:08:08
1. If not X or Y rated, then the caps can be a hazard if connected across the AC line. A fire hazard, a shock hazard, etc. Recommendations such as this are inherently dangerous and should not be espoused to others in a public forum.
The self extinguishing aspect is NOT sufficient to provide enough fire hazard safety, and such experiments should be fused or circuit breakered accordingly
2. A cap value of 55 uF will end up looking like an impedance of approx 50 ohms at 60 Hz. That's a lot of leakage current, well beyond what UL considers safe, and I am sure it violates fire codes as well.
Consider this, with a "normal" AC line circuit, there is not supposed to be a significant voltage difference between the Neutral and the Ground lines. With a 55 uF cap (or more if multiples are used)across the line AT THE COMPONENT, that is no longer the case, and a serious and fatal shock could be delivered from the Neutral line to someone who is earth grounded.
On the whole, this much capacitance is dangerous and too much for the average DIYer or Tweaker to place across the AC line with impunity.
Obviously, you as an individual are free to do as you wish, but to recommend something along these lines to others is unwise and irresponsible.
Jon Risch
Follow Ups:
Is there a commercially available product that is an iec connector and capacitor or filter that is all built into a single housing? Something off the shelf that is a simple mod and I would not have to worry about any safety issues.
Pat
An IEC filter has caps and noise and spike suppression built in.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
What happens to this filter if it is hit by a 5600v surge from a lightning strike? Might it catch on fire or explode? Is it UL or similar agency approved?? T456
Edits: 09/13/16
Mikey,
Do you like these or do you build your own?
Pat
JR, Do you see a shock hazard if the caps are not AT THE COMPONENT, meaning plugged into either the same or a different ac receptacle?
Edits: 08/09/16
In theory, it is slightly better if the caps are not at the component, but at the breaker box.
However, the bottom line is that it is still dangerous.
Jon Risch
Guys, let me tell you cautionary tale about amateurs and electricity.
Push pull system, friends advise him to place a 50uF motor run capacitor across the line and neutral (240 volts, 50 hertz.
Does so and is highly impressed with the new sound.
He then fits a second one - even better. As always, more is better so in goes third one.
Here we use a Ring Mains system where each half of the ring can support 3 kilowatts. The ring main wiring burns out right back to the main board.
Where two units are plugged into the same socket, that burns out completely.
The fuss over it being dangerous to self, is a bit overplayed.
Regards to all.
JohnR
I don't think the type of capacitor the OP is talking about are run capacitors.
An AC run capacitor is designed to be hooked up across the mains, at the motor, continuously. Don't try that with a start capacitor though.https://en.wikipedia.org/wiki/Motor_capacitor
Edits: 08/12/16
I have edited my OP on this issue. I shouldn't have been able to since it is so old and there have been responses. Don't know what's up with that. I did not edit the language in the original post. Aerovox dry type (and oil type) lighting caps are continuous use caps. The tutorials say that shock risk is not a concern with across the line caps and there is a fire danger upon failure in short mode. You can read the exact language in a number of spots. Don't understand the leakage thing in relation to across line caps in failure as a short. Self healing would reduce that risk along with being fused. There are other types of caps that have increased protection from internal shorts. Even Type X safety caps can catch fire and are or can be described as self extinguishing. Maybe they should not be used either? Zero risk with the use of capacitors across the AC does not exist. Tweaker
Edits: 08/12/16
I have edited my OP on this issue. I shouldn't have been able to since it is so old and there have been responses. Don't know what's up with that.
//
Posted by Tweaker456 (A) on August 13, 2016 at 08:29:04
Up until recently there has always been a time limit and once someone replied you could not edit the post. The edit and delete go away. I'm not quite sure what you are talking about. If it were not the case anyone could just change anything they said and it would be unworkable. No discussion would have any merit.
Again,The AA program does not have a time limit or a limit after a response has been posted. I think after a thread has been archived the post can not be edited.
As for the specific caps you are using it would have helped if you would have provided a Link to a site showing the specs for the caps you have.
There are some lighting caps that are made to be connected across the line. There are others that are made to be placed in series with the winding of the ballast. (LC, Inductor/capacitor, circuit.)
http://www.lampholder.net/lampholders/wp-content/uploads/2016/02/high-pressure-sodium-ballasts-wire-diagram.gif
I believe in all cases the cap is there mainly to correct PF, Power factor.Some AC capacitors not only are used to correct PF but also will raise the line voltage. You might want to check the line voltage at the equipment you are using the caps on without the caps connected and then with the caps connected.
Edits: 08/13/16 08/13/16
Up until recently there has always been a time limit and once someone replied you could not edit the post. The edit and delete go away. I'm not quite sure what you are talking about. If it were not the case anyone could just change anything they said and it would be unworkable. No discussion would have any merit.
When I saw I had made a mistake. It's the Subject line you can't edit.
I just edited my previous post.
Check the edit date below the page on my previous post.
Of course you must login, upper right hand corner of the page, before you can edit a post.
You can not delete a post after someone has posted to your post. You can not delete a post after 24 hours.
Signing is is a good idea. Why didn't I think of that. Now my OP in this thread can be edited but no longer deleted. Looks like you can't edit after a certain amount of time.
So I signed in and at first it looked like I couldn't edit post. Now everything seems to come up with edit delete. Many times before when this has happened and I tried to edit a post it would say nice try and wouldn't let me do it because it was already answered or to old?? Why should you be able to completely change a post after it's been out for awhile or was already responded to??
"Where two units are plugged into the same socket, that burns out completely.
The fuss over it being dangerous to self, is a bit overplayed."
Even potentially starting a fire in your house as you posted? Amateurs and electricity are a bad combination and your statement at the end of your post I perceive as irresponsible.
FYI... I am a qualified electrician and have over 25 years experience in industrial electric systems and instrumentation. I understand the theory behind using shunting caps to reduce noise. I have been required on several occasions to install them to put a band aid on a problem. I certainly would not attempt what was advocated by the OP. I would even be hesitant to install Al Sekala's device as mentioned by another poster.
Safety concerns aside, the filtering approach achieved by putting massive shunt caps by themselves is not going to be that much compared with using a much smaller cap in a more optimal filter topology. An RC or CLC topology could allow reduction of the sizes of these multi hundred u farrad caps to only a few mics each at most and probably achieve even better noise filtering. I wouldn't necessarily recommend CLC's for less experienced amateurs due to the inrush current/ back emf over voltage problem that could break downstream semiconductors. RC's seem like they could be a very effective approach a careful amateur might safely have good success killing noise with, however.
Besides, best case scenario this type of filtering can only address differential mode noise. I'm not entirely convinced some common mode filtering along with all this diff mode filtering wouldn't go a long way for a lot of folks looking to quiet down the ac.
I read that there is no concern for shock with caps across the ac. X type caps. are made up to 10uf for sale to the public. So are you saying that there is a shock hazard if more than 10uf are used? I have , as I said before, discussed this with an electronic engineer and he agreed that there was no concern for shock with fairly large amounts of capacitance. I did a fair amount of checking and research about this. Not saying I'm absolutely right on this but I did much to validate the shock safety thing. In a previous discussion with an aerovox agent I was told that the specific lighting caps I talked about and use were Type X. Looks like I was given inaccurate info.
If anyone knows, it is you.
What could be the good of doing it at all? Is there something to be gained or it is just danger with no possibility of improving the quality of the line?
Massive amounts of capacitance across the AC line will tend to filter out EMI to a limited extent, not so much RFI.
IF one were having significant amounts of EMI on their AC line, then the removal of some of that would probably make a positive sonic difference.
However, given that such large amounts of capacitance can be dangerous or even deadly, it would behoove the person inflicted with such EMI problems to track down the source of the EMI, and eliminate it at the source, or provide as much attenuation at the source as possible. Then, just a uF or two might suffice to clean up the left-overs.
The problematic issues with using such large amounts of capacitance directly across the full 120VAC line is one of the big whoopee deal reasons my Super Quick & Dirty Digital filter was so effective but without the downside of a large amount of leakage current: the filtering capacitors were isolated across the back-to-back secondaries of the two transformers, and so, the user never saw the leakage current at all, yet you could pile on fairly large capacitance for maximum filtering effect.
I am referring to this filter:
(SEE: http://www.AudioAsylum.com/audio/tweaks/messages/43988.html
my additional "tweak":
http://www.AudioAsylum.com/audio/tweaks/messages/47160.html )
Other folks have tried it using 1 to 1 iso transformers, of a size that does not limit the wall outlet current maximum (essentially a 2000W transformer). Have to use full AC line rated X caps here but it still has very low leakage current.
Jon Risch
Putting mfd range caps across the AC line will shift power factor. Unless you have a power factor problem and need to do that it serves no purpose. And determining if you have a power factor problem is way beyond the general knowledge on this forum. In a residence you don't worry about power factor.Power factor is the lead/lag of the current vs voltage. That's right, current out of phase with the voltage! Wrap your mind around that idea.
Thinking that a mfd range cap does a better job filtering out RFI than a mmfd cap is just novice logic. If you have a bad RFI problem then you need a Pi filter.
Edits: 08/09/16 08/09/16
"Thinking that a mfd range cap does a better job filtering out RFI than a mmfd cap is just novice logic. If you have a bad RFI problem then you need a Pi filter."
In case you really want to know, look up Capacative reactance.
Uncle Mike, Setting aside the safety concern let me address the novice logic comment. In listening tests larger capacitance sounds better, plain and simple. It looks like it would be kosher from a safety point of view to compare an across the line say .47 to a 10uf Type X safety capacitor without too much effort or expense. IMHO, YMMV This is not based on theory or math but direct experience. Pretty much the reason for most if not all of my comments about recommendations. Anyone who either feels or knows that any of this is dangerous than don't do it. T
Your story has changed. You've gone from claiming 300uf capacitance to only 10uF. Seems like backpedaling to appear more reasonable within the forum. You seem to have a desire to make enormous capacitance values and massive wire gauges to be groundbreaking options to present to the forums, with no other explanations of what they actually do other than it "sounds better" to you. I have serious doubts about the veracity and intent of your eccentric evaluation processes other than coloring the sound just for the sake of it. If 300uF capacitance "sounds better" to your ear than a proper value capacitor for RFI suppression, then something must be seriously skewed in your audio system. Perhaps you are unknowingly attempting to provide a fix for one or more unknown radical tweaks you've previously done to make it "sound better".
First of all I never actually recommended 300uf across the AC, it's what I use. I did recommend larger than X type come in by accident because the manufacturer, Aerovox, told me they were X type. So if JR says they may be hazardous don't anyone use them. The 10uf x type look like they have been vetted for safety. The contention that if something sounds better it means there is something skewed in my system seems just another way to make everything I say seem false. And if it were true that there was something wrong that was remedied, I say hallaluya. Sounding better to me is good enough. I ain't backing down from that. I thought that's what we are here for. Except me, who is just an egomaniac trying to give people false info. Or just plain deaf. I prefer the latter as an insult but you can take your pick. Thick(er) wire, conductive greases, brass as footers, brass being better sounding than carbon fiber, the use of EAR isodamp as an excellent vib absorbing product are all things perceived by others. This whole hobby is substantially about opinion and experimentation. Maverick
Edits: 08/09/16
Tweaker456 wrote:
"First of all I never actually recommended 300uf across the AC, it's what I use."
That's more backpedaling on your part. In most cases, when end users post information about a configuration they choose for a particular application, that information is implicitly a suggestion, recommendation, or otherwise opinionated advice with an inference of propriety. Furthermore, since Audio Asylum not just a come-and-go chat room, you have to own what you say in a public forum. Search engines including Google and the AA Archives can provide valuable advice and insights that folks may come across over the course of many years, so you really should watch what you say, especially when it comes to any information about modification of the AC delivery path. Many years ago, when I posted a DIY report about a power cord I built with bulk-length speaker cable, I later came to greatly regret posting that potentially dangerous information, and still fully regret doing such an irresponsible thing, even to this day.
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