AudioCircle
Audio/Video Gear and Systems => Power Conditioning => Topic started by: Occam on 11 Aug 2013, 05:44 pm
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A while back, an occasional poster, rdsu, asked about ground conditioning chokes -
Interesting! :)
On Felix Topic, the authors and testers found that the best chokes for amplifiers, at 115V, that doesn't constraint dynamics, are the JW Miller (http://www.bourns.com/data/global/pdfs/8100_series.pdf) 17A ou 20A. For 230V the 9.3A was used with success, maybe because of more current available...
Even the JW Miller 9.3A has more Inductance and less DC Resistance than Coilcraft 5A.
I have a friend that use Coilcraft 10A for their Amplifier, and he likes the result...
Did you also test them?
For Earth, you can try Schurter DENO (http://www.schurter.ch/en/Components/EMC-Products/Suppression-Chokes/DENO) ...
I think these Schurter doohickeys are ideal for their task, providing substantial inductance in a very small, purpose built package. I'm surprised no one has commented positively.
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Occam,
After learning about the DENO units I ordered a few. You know what? I like them. I plan to continue use of them. The key to this is to use star wiring that is fed by the DENO, into isolated ground sockets. The box can be grounded before the DENO, or not. Another method is to use a grounding plate that is isolated from the box (connected, not as wire), then the DENO, and then isolated star grounding. The best part is they are cheap, so the added price to a unit is negligible.
Take a look at where the DENO's frequency range is at. I think you'll have your mh explanation there. They are basically romex solid wire wound around a donut. I don't think there is a need for worry because the inductance just isn't anywhere near line. Unless there is a secret subliminal .3mhz frequency in the EU at high amperage, that I'm unaware of....
Bybee's work well on ground as well. I've done a DENO and a Bybee into star grounding. It's on the unit with 17x Bybee's. It is STELLAR, but incredibly expensive.
I realize the one I linked too does way less. It's still a fascinating unit that inducts by looping onto itself. I thought the guy might be interested in developing some other practical stuff (we could use), but no.
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Hi Occam,
I use it on my "Felix (http://www.audiocircle.com/index.php?topic=25757.msg1221696#msg1221696)" and works very well without issues...
Thanks one more time for your help! ;)
Regards
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You also have more options:
- Schurter DEH (http://www.schurter.ch/en/Components/EMC-Products/Suppression-Chokes/DEH)
- Schurter DEN (http://www.schurter.ch/en/Components/EMC-Products/Suppression-Chokes/DEN)
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The potted unit appears to be the same as the DENO, just, you know, potted. It's also more than twice the price.
The biggest upgrade is the super low impedance grounding mixture you can put your grounding rod into. It's all the rage for recording studios I guess.
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Placing any reactive device into the grounding path of an AC feed it not a very wise idea. The reactance of the device will limit the bolted fault current, which will alter the time to clear the breaker in the event of a fault.
Doing this can cause the short current to exceed the ampacity of the wires.
jn
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I'm with jn. I don't understand why you need to condition a conductor that is not supposed to carry any current. This is a safety conductor used to bleed current away from a fault.
Wayner
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I doubt the reactance of the DENO could be a problem. The range it works in, the type of wire, and the amount of resistance don't point towards a reactive quality during a ground fault. jn do you really think it'd even be noticeable? I doubt dozens of them in a row would make a difference.
Ground noise is very real. Again the special earth ground rod blocks that can be poured change the situation significantly, but not many of us have that option. For example balanced cables could dump noise with the right impedance situation, through the earth grounded enclosure one pin is connected too, but as is now there isn't a consistent factor for where the noise goes. One member on the forum dislikes Y caps in a system with balanced interconnects because the noise ends up on ground, and then affecting the equipment with balanced interconnects. Maybe it is even Occam, I forget.
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I doubt the reactance of the DENO could be a problem. The range it works in, the type of wire, and the amount of resistance don't point towards a reactive quality during a ground fault. jn do you really think it'd even be noticeable? I doubt dozens of them in a row would make a difference.
A few points..
NEC 250.8(B) does NOT allow the grounding and bonding of electrical equipment where the connections depend solely on solder.
NEC 250.102(D) requires the bonding conductor always be #14awg or larger.
NEC Article 100 defines "Grounded, Solidly" as "connected to ground without inserting any resistor or impedance device."
The bonding of equipment MUST guarantee that during a fault, the exposed surfaces cannot exceed 50 volts. Inductance placed in series with the grounding conductor does not guarantee that.
"Dozens of them in a row" virtually guarantees that you have moved the fault current from the magnetic regime of the load panel circuit breakers into the thermal regime. Faults will no longer clear in two or less line cycles, and you float the chassis off ground potential.
Edit: Actually, your statement is extremely dangerous..
An inductor of 22 millihenries will cause the shorted current to be 14.46 amperes in a 120 volt line, and will not clear the line, leaving a chassis at 120 volts indefinitely.
4 mllihenries will cause an 80 ampere fault current.
If one examines the time/current curve for a typical magnetic breaker, 80 amps on a 15 ampere breaker is supposed to clear the breaker in the range between 4 and 15 seconds. While 15 seconds may not seem long to some, to others it can be a lifetime.
It is NEVER a good idea to insert any component in series with the safety bonding conductor. There is a good reason for that.
So, to answer your question.....jn do you really think it'd even be noticeable?
Yes. I suspect death can be noticeable. Or even just brown underwear.
jn
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It seems strange that a company who's mission is:
SCHURTER is an internationally leading innovator and manufacturer of fuses, connectors, circuit breakers, input systems and EMC products as well as a PCB assembly service provider for the electronics industry.
Would have a product like a:
DEH EMV Inductor: High frequency ground wire choke,
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You're talking about electrical bonding. Those codes mean nothing for those that are using these items in electronics. I'm certain Schurter didn't intend for their devices to be used in electrical bonding situations. Correct me if I'm wrong but I'm unaware of any audiophile that build their system into the conduit of their pool.
Nothing is rated near 80a in the case of electronics. The very socket in the wall is not. Many devices have fuses as well.
The resonant frequency of the DENO is .3mhz. I'd like to know how you figure 60hz is going to become thermal.
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The safety of and the rules for DIY equipment is the same as for store bought equipment. The situation is if there is a short circuit then the Safety Ground circuit must be as robust as the Hot & Neutral. If a Safety Ground connection fails in that fraction of a second, then the breaker doesn't trip and someone could get electrocuted.
'electrical bonding' means a robust and secure permanent connection.
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Speedskater I always appreciate your interest in reading about safety, but mis-categorizing safety isn't helpful. This board has for whatever reason begun to make a habit of this.
Electrical bonding. (http://en.wikipedia.org/wiki/Electrical_bonding)
NEC: National Electrical Code (http://en.wikipedia.org/wiki/National_Electrical_Code). It doesn't have squat to do with electronic components. That field is only sometimes governed by UL depending on individual counties.
DIY equipment is often much more robust and safer than store purchased items. I understand the breaker situation. No one here has actually brought up a conflicting argument from safety. Codes that don't apply and have a different purpose (and are generally met by those using these products), unexplained reasoning of induction in different frequency ranges, non-complaints about size of wire, demands for current loads far exceeding the rating of the romex feeding anything anyone would use one of these units in....
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I gave a very informal explanation of bonding. Yes the NEC definition is much stricter as in attached forever.
I never suggested that NEC code was the only organization that applies to safety.
If the store bought equipment has a real safety sticker then we know the a knowledgeable organization tested it.
Some of the posts in the 'power conditioning' forum make me wonder about their DIY equipment's safety.
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It is very important you discontinue the diversionary strawman tactics, they only serve to obscure the issue.This sentence as a point:
Correct me if I'm wrong but I'm unaware of any audiophile that build their system into the conduit of their pool.
The discussion has NOTHING to do with conduits nor pools. STOP. LISTEN. NOW. IT IS VERY IMPORTANT YOU UNDERSTAND.
You're talking about electrical bonding. Those codes mean nothing for those that are using these items in electronics. I'm certain Schurter didn't intend for their devices to be used in electrical bonding situations.
I do not care what Schurter intended. I care about safety. The name of this thread is Safety Ground Conditioning .
A safety ground is a ground used for safety. PERIOD. The purpose of a safety ground is to clear the breaker in the event a fault within a piece of electronics could cause the chassis to become energized. And, while doing so, keep the chassis potential at a non lethal level.
Placing inductance within that path alters the fault current which clears the breaker. Sufficient inductance can prevent the breaker from clearing.
Nothing is rated near 80a in the case of electronics. The very socket in the wall is not. Many devices have fuses as well.
It is important you follow the argument. Go back and re-read what I said.
I'd like to know how you figure 60hz is going to become thermal.
Again, follow the discussion, or learn it. A circuit breaker has two modes of operation. One is thermal, and the other is magnetic.
I apologize for being so hostile sounding. This is a safety concern, and I do not take hostages when safety is involved.
jn
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About earth, I based my power conditioner on these two examples:
IsoTek GII SIGMAS
(http://img547.imageshack.us/img547/1340/ndjq.jpg) (http://imageshack.us/photo/my-images/547/ndjq.jpg/)
Shunyata Hydra Triton
(http://img51.imageshack.us/img51/2045/cmu3.jpg) (http://imageshack.us/photo/my-images/51/cmu3.jpg/)
I used the Schurter DENO 16A version, but at least I should use the 25A that has less resistance...
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An Introduction to AC Ground-Fault Loop Impedance Testing (http://www.econline.com/doc/an-introduction-to-ac-ground-fault-loop-imped-0001) ?
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An Introduction to AC Ground-Fault Loop Impedance Testing (http://www.econline.com/doc/an-introduction-to-ac-ground-fault-loop-imped-0001) ?
A very nice link, the writing is not overly technical but provides good information.
One point. The tables they provided are for 120 volt systems.. Members here who have different voltages must recalculate accordingly.
Note that the impedance of a 10 mH inductor at 60 hz is 3.7 ohms.
Also very important: Those tables use 500% fault current, and expect the breaker to clear in about 1 second. If you look at the 15 ampere with 75 amps fault, and then look at the time/current chart of a circuit breaker, you may find that the actual time to clear is between 5 and 15 seconds by design.
For that table and typical breakers, the chassis will be energized at FULL LINE VOLTAGE for a time between 5 and 15 seconds.
Note: This assumes a hot to chassis short of course. It is the worst case, and the reason for a safety ground.
Another note: If you have two devices, like a pre and amp, and one shorts to ground, you are now using the shield of the IC to try and hold chassis potential down.
jn
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Thoughts:
a] An additional 3.7 Ohms will definitely slow down a breakers trip time by a lot. If the total series impedance is 8 Ohms, a 15A breaker will never trip.
b] If a 15A circuit is used to power a bunch of old fashioned filament light bulbs. If the continuous current is 12A (all that's permitted in a 15A circuit) then the cold turn-on current could approach 120A in the first second.
c] While the safety margin continuous current limit for common 14AWG wire is 15A the real limit is 27 to 29A. But under fault conditions that 14AWG wire will fail after 1 second at 600 Amps.
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Another note: If you have two devices, like a pre and amp, and one shorts to ground, you are now using the shield of the IC to try and hold chassis potential down.
jn
Good thread!
Assuming both components are grounded then the ground wires in the power cords and building wiring also connect the grounds along with the IC's ground wiring.
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Earth-fault loop impedance values (http://www.tlc-direct.co.uk/Book/5.3.4.htm), for 240V.
MAXIMUM EARTH FAULT LOOP IMPEDANCE VALUES FOR OVERCURRENT PROTECTIVE DEVICES IN COMMON USE, FOR FAULT PROTECTION (http://www.esc.org.uk/fileadmin/user_upload/documents/industry/faqs/master_EARTHFAULTLOOPtable.pdf)
Should I remove the earth choke?
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b] If a 15A circuit is used to power a bunch of old fashioned filament light bulbs. If the continuous current is 12A (all that's permitted in a 15A circuit) then the cold turn-on current could approach 120A in the first second.
I suspect the incandescent bulb transient is in the tens to maybe 100 millisecond range, but do not recall any data on that.
c] While the safety margin continuous current limit for common 14AWG wire is 15A the real limit is 27 to 29A. But under fault conditions that 14AWG wire will fail after 1 second at 600 Amps.
600 amps is 40 times rating, that falls into the magnetic operation of a 15 amp breaker. It clears in 1 line cycle, or 16.6 milliseconds.
http://static.schneider-electric.us/docs/Circuit%20Protection/Molded%20Case%20Circuit%20Breakers/0100-400%20A%20Frame%20FA-LA/FA-FC-FH/0600DB0105.pdf
Page 2 has a typical curve for square D.
jn
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Good thread!
Assuming both components are grounded then the ground wires in the power cords and building wiring also connect the grounds along with the IC's ground wiring.
If you assume that a "box" is used and all components are plugged into is like the second picture, then indeed all the chassis will go to the same potential. So while dangerous voltages may appear on the chassis, it will appear on all of them.
If one component has it's ground via a different inductor, there will be an inter-chassis potential difference, and the IC shield will be hit very hard. If it opens, the electronics at both end of the IC are also toast.
jn
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Earth-fault loop impedance values (http://www.tlc-direct.co.uk/Book/5.3.4.htm), for 240V.
MAXIMUM EARTH FAULT LOOP IMPEDANCE VALUES FOR OVERCURRENT PROTECTIVE DEVICES IN COMMON USE, FOR FAULT PROTECTION (http://www.esc.org.uk/fileadmin/user_upload/documents/industry/faqs/master_EARTHFAULTLOOPtable.pdf)
Should I remove the earth choke?
Do you have children?
I believe following code is the best option. Oh, btw.. are the devices UL?
I am reminded of the old dirty harry scene... In all the confusion, I don't recall if I fired 5 times, or 6..are you feeling lucky...
jn
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jn, safety is within understanding. It's respect, not fearful avoidance. Respect produces predictability, fear produces a defense position that is regardless of predictability.
I'm not sure why you are comparing a 10mh inductor now.
If only earth ground was nearly as effective as we would like. (http://www.mikeholt.com/technical.php?id=grounding/unformatted/GroundResistance&type=u&title=Ground%20Resistance%20-%20It%27s%20Not%20What%20You%20Think%20%2812-30-99%29)
The resistance of the DENO's are rated in milliohm
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That earth ground in the dirt only matters in thunderstorms and the like. Inside a building the Safety Ground's job is to trip it's circuit breaker if there is a fault (short circuit). The less series resistance/impedance of the Safety Ground wiring back to it's circuit breaker box, the better.
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jp, safety is within understanding. It's respect, not fearful avoidance. Respect produces predictability, fear produces a defense position that is regardless of predictability.
I assume you meant jn..
I am not avoiding anything because of fear. I am pointing out the very serious safety errors you have presented. Insertion of a device with impedance into a safety conductor is dangerous.
I teach advanced electrical safety outside the scope of what we would call normalcy...your misconceptions are going to end up as part of my course material. In fact, I believe the standard safety course given as a precursor to mine already has some of this stuff in it.
I'm not sure why you are comparing a 10mh inductor now.
I am not comparing anything. I pointed out what the inductive reactance of a 10 millihenry coil was at 60 hz to show the level of effect.
If only earth ground was nearly as effective as we would like. (http://www.mikeholt.com/technical.php?id=grounding/unformatted/GroundResistance&type=u&title=Ground%20Resistance%20-%20It%27s%20Not%20What%20You%20Think%20%2812-30-99%29)
MIke Holt is a great site and resource. Unfortunately, you are linking about earthing? We are discussing safety bonding of equipment chassis, not earthing for lightning strike protection.
The more you post, the clearer your lack of understanding on grounding and earthing becomes. As I said, please learn this stuff. What you present is dangerous.
The resistance of the DENO's are rated in millionths of an ohm.
Where are you getting this??? A #12awg wire has DC resistance of 1.7 milliohms per foot. One inch is 141 millionths of an ohm.
The term m ohm means milliohms, not micro-ohms.
jn
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Do you have children?
Yes, 14 months old... ;) That is why I really need to know...
Where are you getting this???
From here: Schurter DENO (http://www.schurter.ch/en/Components/EMC-Products/Suppression-Chokes/DENO)
(http://i.imgur.com/Y1e2B2B.jpg) (http://imgur.com/Y1e2B2B)
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Yes, 14 months old... ;) That is why I really need to know...
From here: Schurter DENO (http://www.schurter.ch/en/Components/EMC-Products/Suppression-Chokes/DENO)
(http://i.imgur.com/Y1e2B2B.jpg) (http://imgur.com/Y1e2B2B)
Ah, my apologies. It was a rhetorical question. I had examined the link before, so knew of the 2 to 4 mH inductance.
Quite honestly, the possibility of your system having a hot to chassis fault is very low. The real question is.. is the risk, no matter how low in probability, worth it?
When loved ones are involved, is any avoidable risk worth taking? To me, I weigh risk probabilities based on the cost of the worst possible outcome. With children, that cost is infinite.
jn
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As a child I stuck my fingers with tools of some sort into PLENTY of AC outlets.
I am still, sad to say, alive.
(I did see my 280lb dad get tossed five feet across a room while trying to fiddle in the back of our tubed, not solid state color TV while it was turned on, back in the 1960's, which I would guess was he touched the high voltage something..)
In 64 years I have never had an electrical component fail to a live chassis. Nor have I read nor heard of ANY child anywhere getting electrocuted by a stereo component which was improperly grounded.
So I have to say the worry about our precious children may be a little over the top?
Just my opinion there.
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I think these Schurter doohickeys are ideal for their task, providing substantial inductance in a very small, purpose built package. I'm surprised no one has commented positively.
on the second page... and no one finds it interesting odd that this ground choke is a differential 2 terminal inductor, one inch in diameter, weighing 1 ounce
(http://www.audiocircle.com/image.php?id=85329)
and yet, it is rated 16 amps and 4 milli Henrys?????????
Well, actually, not at the same time.... 8)
EDIT:changed differential inductor to 2 terminal inductor
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Sorry, yes, jn. And Millionth is the spell-check word that comes up for milliohm; a habitual mistake.
Actually according to what you said, a 4mh device is perfectly fine but...
Occam's the one pointing out the rating concerns. The resonate frequency, again, is .3mhz. "Not at the same time," as he says for current, induction (and there for series reactance properties).
The reality is that it isn't a very strong filter.
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Occam's the one pointing out the rating concerns. The resonate frequency, again, is .3mhz. "Not at the same time," as he says for current, induction (and there for series reactance properties).
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Nope.
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?
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As a child I stuck my fingers with tools of some sort into PLENTY of AC outlets.
I am still, sad to say, alive. (there is only so far the regulating agencies can go to counter the stupidity of the average individual. I can also say that it does indeed hurt, me it was a pair of small scissors.)(I did see my 280lb dad get tossed five feet across a room while trying to fiddle in the back of our tubed, not solid state color TV while it was turned on, back in the 1960's, which I would guess was he touched the high voltage something..) (good guess. Early color TV's had inefficient phosphors, 17kv was pretty much the level.)
In 64 years I have never had an electrical component fail to a live chassis. Nor have I read nor heard of ANY child anywhere getting electrocuted by a stereo component which was improperly grounded. (Nor I. Look up the stats on electrocutions in the US alone. Granted, a few hundred dead out of 300 million is very small.)
So I have to say the worry about our precious children may be a little over the top? (or significant other, or sibling, or burning the house down..name your poison.)
Just my opinion there.(no prob)
But your position seems to be to ignore safety problems because you haven't experienced it? Do you believe that is a reasonable stance to present on a DIY forum?
jn
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on the second page... and no one finds it interesting odd that this ground choke is a differential inductor, one inch in diameter, weighing 1 ounce
(http://www.audiocircle.com/image.php?id=85329)
and yet, it is rated 16 amps and 4 milli Henrys?????????
Well, actually, not at the same time.... 8)
I'm not sure what is interesting or odd. The datasheet I see doesn't say differential inductor, so I'm also not sure what is meant by that.
16 amps seems ok, as does 4 millihenries.. Why not at the same time? Are they indicating that it saturates, dropping inductance as a consequence? I didn't see a current vs inductance graph.
jn
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Sorry, yes, jn. And Millionth is the spell-check word that comes up for milliohm; a habitual mistake.
I too used to be able to spell, and then spellchecker arrived..sigh.
Actually according to what you said, a 4mh device is perfectly fine but...
Don't let the numbers confuse. Think about the system during a fault.
a 4 mH inductor will have a reactance of 1.48 ohms. At fault, that will draw 81 amperes.
In a 15 ampere branch circuit, that represents a factor of 5.4 over the nominal. The breaker will break in the timeframe of 3 to 12 seconds. Until that interval has passed, the chassis will be at 120 volts.
In a 20 ampere branch circuit, the factor is now 4. The 20 amp breaker will clear between 6 and 20 seconds. Again, the chassis will be at 120 volt potential during that interval.
In a 30, the factor is 2.66, 15 seconds to 60 seconds with a chassis at 120 volts..
Note that for all breakers, they are designed NOT to open faster than the low time point shown on the breaker time/current curve.
My point here is: This discussion is all about a SAFETY FEATURE used to protect us. Insertion of an inductance into the bonding conductor must NEVER be done without engineering analysis to determine the level of effect the compromising of a safety feature will have on the overall system.
You in fact, did not understand the use of the term "thermal" with respect to a circuit breaker.. Consequently, you had no idea that the use of these devices in the safety conductor would cause a chassis to be AT LINE VOLTAGE for a time period designed in by the circuit breaker manufacturer.
You can no longer claim that lack of knowledge..
To all: a circuit breaker is there for only ONE reason. That reason does not include the protection of human lives directly. It's sole purpose is to protect the wires from the breaker to the load. Nothing more, nothing less.
It is our responsibility to make sure that during a fault, humans are protected. That is why insertion of an inductance in the safety grounding conductor without proper engineering is so dangerous, it compromises safety.
jn
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jn, I thought you were saying the induction device would become thermal? I don't think "thermal" is an overly complicated function.
I'm contacting the company because several factors will influence our concerns here about safety. There are simply questions not answered.
jn, might I suggest that you do your best to explain with information, and not a projection of how you feel people need to be safe. For example Elizabeth's values on safety vs. sound quality vs. risk vs. family, etc may be different than yours. If we wanted to be really safe we'd just not use electricity... Yet for whatever reason we have been using since the dark days when almost all electrical stuff was much more dangerous than anything discussed in this thread. I mean AC receptacle sockets way back would fail by shooting a fireball out of them... Anyway, give people all the information they can possibly use and then accept that they can do whatever they want, wrong or right, because they are sentient. Become concerned when they are wiring public buildings and make them stand up to code.
I have a fuse in my apartment (old), and there isn't any ground wires. I've grounded my listening system's socket to the conduit for some added protection. But as you may imagine I don't live with the safety that you'd promote. Yet the building and occupants have been around longer than either of us (and probably our ages combined).
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jn, I thought you were saying the induction device would become thermal? I don't think "thermal" is an overly complicated function.
No. The statement I made (quoted after this sentence) was based on your statement:
"Dozens of them in a row" virtually guarantees that you have moved the fault current from the magnetic regime of the load panel circuit breakers into the thermal regime.
Your statement appears to be only considering the DC resistance of the elements. If it were only a dc circuit, you would be correct. It is the inductance which is the problem.
Most of the panel mount circuit breakers have an area of operation where a thermal heating device opens the breaker in a clearly defined time fashion, and a second regime where a magnetic element opens it up. Many who do not know circuit breakers do not know of this fact.
I'm contacting the company because several factors will influence our concerns here about safety. There are simply questions not answered.
Always a good thing. But just be wary as they are in the market to sell product.
jn, might I suggest that you do your best to explain with information, and not a projection of how you feel people need to be safe. For example Elizabeth's values on safety vs. sound quality vs. risk vs. family, etc may be different than yours.
Everybody weighs things differently. I pointed out MY weighing scheme. It actually does not matter to me how others weigh risks.
What DOES matter to me is that when someone makes a decision to alter or ruin a safety device, that they know exactly the ramifications of their actions. For this specific item, it's use will totally destroy the safety conductors ability to keep the equipment external surfaces from rising to lethal levels, and without any engineering involved, some combination could actually eliminate the system's ability to force the breaker to clear the line, leaving lethal potentials on external surfaces unchecked.
Given that the home environment is in essence an uncontrolled one, this action has the ability to subject others to lethal potentials in the event of a fault. Others who are unknowing.
I didn't say people cannot make decisions based on their own weighing scheme. I say, understand the ramifications of the decision.
If somebody is injured or dies as a consequence of ignoring my safety concerns, it cannot be said that it was not understood.
Sigh..you really need to break away from this hyperbole/strawman schtick you keep trying to use...it serves no useful purpose.
If we wanted to be really safe we'd just not use electricity... Yet for whatever reason we have been using since the dark days when almost all electrical stuff was much more dangerous than anything discussed in this thread. I mean AC receptacle sockets way back would fail by shooting a fireball out of them... Anyway, give people all the information they can possibly use and then accept that they can do whatever they want, wrong or right, because they are sentient. Become concerned when they are wiring public buildings and make them stand up to code.
The reason Code it there is to protect us. It is updated every three years to fix errors, omissions, newer understandings, newer technology. Your argument is tantamount to "hey, it's a dangerous world, so lets ignore the safety features others are attempting to impose on us.
But as you may imagine I don't live with the safety that you'd promote.
Don't be silly, of course you do. You just are unaware of a lot of the technology. Your building wire guage was defined by code. Your fuses were defined by code, the outlets..
How many pieces of electrical equipment do you own with a 3 prong cord, where the manufacturer disabled the safety ground conductor? How many do you think exist out there?
I can confidently say, none. And I guarantee that none of them condone the practice of adding a component to their equipment to bypass the safety function either.
I've never been in a car accident, but I use seat belts and have not disabled the air bags.
If someone on an internet forum made the argument that they've never been in a car accident so seatbelts are unimportant, would you jump off that cliff as well?
Please be more cognizant of the arguments you present on a public forum. The casual and uninformed disabling of safety items for use in a consumer home environment can have serious consequences.
And if you're going to provide anecdotal examples, make sure they are applicable, relevant, and viable.
jn
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But your position seems to be to ignore safety problems because you haven't experienced it? Do you believe that is a reasonable stance to present on a DIY forum?
jn
Yes. When the 'safety' is so extreme it is over the top.
Just like worrying that using an aftermarket powercord will invaidate your home insurance in case of fire because none of the aftermarket cords are UL rated. (which is a claim bandied about by other 'too safe' worrywarts..)
Not one instance of an audiophile getting denied insurance has ever been mentions on the internet with it being due to the cord not being UL approved. So it DOES get to be a BS overkill too many times.
And I am just pointing that out for the folks who like to spout this sort of stuff.
Now yes it is true mentioning it is good.. As: It would be somewhat unsafe per these reasons: blah blah.. would be nice for all to understand. But to couch the message in terms with dire consequences.. Like "Your children will all die" sucks.
You do NOT have to make it overkill. a nice comment is all you need.
Aded: and your comments after the quoted post i wrote about are a little better. I read the responses and they do not exhibit that overthe top stuff. Rather a more reasoned comment.
So maybe it was just the 'Save the children' which got me annoyed.
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Ah, and one more engineering concern.
If I use a 4 mh device on a 120 ground, I will pull 81 amperes.
The longest trip time for a 15 amp breaker is 12 seconds, a 20 amp can run to 20, and the 30 amp can run to 60 seconds before trip.
Is the wiring of the device capable of sustaining that current for 12, 20, or 60 seconds?
If I wire them via a printed circuit board, will the traces and solder joints be sufficient to withstand that current for that duration?
If the answer to either question is "I don't know", THEN YOU NEED TO FIND OUT.
If the answer to either question is no, then what you have setup is a condition where the weak link will be cleared instead of the breaker, leaving the equipment permanently energized to 120 volts.
I repeat, this type of modification to a safety system requires engineering analysis.
jn
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Aded: and your comments after the quoted post i wrote about are a little better. I read the responses and they do not exhibit that overthe top stuff. Rather a more reasoned comment.
So maybe it was just the 'Save the children' which got me annoyed.
Clearly your viewpoint was tempered by previous experience with nutcases. I am not one of them. Sorry if that mention annoyed you.
I've used cords with broken ground pins, table saws without antikick guards... drafted a tractor trailer on an interstate at 65mph on a ten speed...
But I do not condone those practices on an internet forum where uninformed people (in this discussion case, possibly non technical people)may be taking the advice.
In fact, I believe the concept of insertion of an inductor in the safety conductor is banned on a forum by virtue of the danger. I had thought it was this forum, but it may actually be diyaudio.
jn
-
Questions for you on separate cover, slightly off topic... I'm curious.
Just like worrying that using an aftermarket powercord will invaidate your home insurance in case of fire because none of the aftermarket cords are UL rated. (which is a claim bandied about by other 'too safe' worrywarts..)
Not one instance of an audiophile getting denied insurance has ever been mentions on the internet with it being due to the cord not being UL approved. So it DOES get to be a BS overkill too many times.
How would it be possible to determine from the charred debris, if a line cord was UL approved or not? Electrical fires happen frequently, it can be assumed that occasionally one might actually start because of a frayed cord or bad plug., and being the epicenter of the blaze, is pretty much consumed. While a fire inspector may be able to determine the point of origin, why would we expect that person be professionally trained to determine if a totally destroyed charred mess that used to be a cable was not UL approved?
As such, you argument that "not one instance....due to non UL approved" is so totally flawed as to be inconceivable as a point of information.
Like the doctor who killed every patient he ever saw, but makes the claim that none of his patients have ever complained about their care.. while true on the surface, it doesn't tell the whole story.
jn
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Bill Whitlock wrote:
Consumer audio and video equipment
electrocuted 9 people in the U.S. in
1997, the latest year for which statistics
are available. That same year, this
equipment caused 1,900 residential
fires which resulted in 110 civilian
injuries, 20 deaths, and over $30
million in property losses.
http://www.jensen-transformers.com/an/generic%20seminar.pdf
********************
Mike Sokol has a web-site about musicians who have been shocked or sadly electrocuted!
Musician Safety | No~Shock~Zone
http://www.noshockzone.org/category/musician-safety/
*********************
Another hi-fi forum does not permit any positive discussion of dangerous projects.
-
I'm not sure what is interesting or odd. The datasheet I see doesn't say differential inductor, so I'm also not sure what is meant by that.
16 amps seems ok, as does 4 millihenries.. Why not at the same time? Are they indicating that it saturates, dropping inductance as a consequence? I didn't see a current vs inductance graph.
jn
Jimmy,
I suppose your experience with chokes is on significantly larger ones than those under discussion. A 1 inch, 1 ounce, 16amp, 4 mH choke is simply from a size perspective, absurd. I asked the Stateside Schurter reps about this a few years ago, positing that with a couple of milliamps running through it it measured its nominal inductance, but when presented with larger currents, it saturated, dropping inductance down to a equivalent air core inductor, presenting minimal impedance to do its job of clearing a breaker. Schurter's response was that indeed this was how it functions, but given language difficulties, I wouldn't use them without verification on my own.
Per Schurters own documentation -
http://www.elektronik.ropla.eu/pdf/stock/tim/de_deh_den_deno.pdf
The most important conditions:
Wire cross section ≥ wire cross section earthed of ground wire choke conductor of equipment
Conductor cross section ≥ 1 mm2 at 16 A
1.5 mm2 at 20 A
Voltage drop across choke ≤ 4 V a.c. at 4 x INom.
I believe the above refer to EN 138100 & EN 60938-1
Its actually moot as Schurter does not import the DEN/DENO-40 into North America and that's the only one with a wire cross section >= 1.5mm2. When one plugs a 15 amp plug, NEMA 5-15P, into an outlet, one doesn't know if the outlet is fed by a 15 or 20 amp circuit, so one should assume a 20 amp circuit.
While its relatively easy to repurpose available Stateside components to meet those requirements for a 20 amp circuit, given the tenor of the discussion, it seems unadvisable to discuss this.
RDSU ,
While these ground chokes seem to have caused much contention, I'd like to thank you for bringing them up here on AC.
Regards,
Paul
-
jn, there are no 3-prong AC receptacles in my building besides the ones I've put in, where the ground is connected to conduit (high enough resistance that it'll take a long time to clear, only the fuses are going to pop, not the breakers). I'm not sure how to explain the language you use, and how it comes off. But basically people can come to their own conclusions with more minimal information not including the caps-lock words (perceived as raised voice); no need to be so pessimistic. Reading your responses makes you sound like you have blood pressure problems from stress. You're not the first person to have an "attack" manner on here. - I don't think anyone isn't interested in what you have to say, but how you say it is what people are responding too. -
UL isn't legal code except in some places. It's just a valuable certification that makes some good confidence. It can be used as reference in legal matters, but not enforced in counties that haven't required it.
There is a limit to "nanny" law and behavior that people are interested in. I think this thread might be touching on it.
The most dangerous electrical things are cheap sockets (99% are), too cheap circuit breakers (often old ones), and cheap electronic devices including bad cords. The DIY and commercial products in the Audiophile world tend to be over-built by comparison.
Occam I asked Schurter some specific questions. They said they'd have to ask the engineers that aren't in the USA. Your thought on the function was somewhat along what I had thought, especially because of the resonate frequency. But we'll see what they say about it, again.
If any of you can think of a good test experiment to seriously gauge how affective these are in a fault, I might be able to give it a worst-case scenario test. Maybe I'll come up with something, but I don't particularly believe there is an issue.
-
I would think that for most of us, codes, rules or tests from:
UL
CSA
ETL
NEC
TUV
or
IEC
will apply.
-
jn, there are no 3-prong AC receptacles in my building besides the ones I've put in, where the ground is connected to conduit (high enough resistance that it'll take a long time to clear, only the fuses are going to pop, not the breakers).
Aaaarrg! :cry:
You might consider doing it 'by the book', in a far safer, NEC compliant manner -
http://www.mikeholt.com/technical.php?id=grounding/unformatted/recept2wire&type=u&title=GFCI%20-%20Receptacles%20Without%20A%20Ground%20(12-30-99
and no ground loops, (or ground chokes) too boot!
-
Aaaarrg! :cry:
You might consider doing it 'by the book', in a far safer, NEC compliant manner -
http://www.mikeholt.com/technical.php?id=grounding/unformatted/recept2wire&type=u&title=GFCI%20-%20Receptacles%20Without%20A%20Ground%20(12-30-99
and no ground loops, (or ground chokes) too boot!
I put GFCI's in a couple spots that I could. The rest has no options, and devices with ground pins have to be used. One socket has ground pin, but there isn't a ground. (can't cook without it)
Trust me I know "aaaarrg" about the wiring. If only I could tear into walls and such, but it isn't my building.
It'd be nice if they had to update it, but it hasn't changed owners in decades.
-
Occam,
Safety concerns aside and just for academic clarification please,,, can you tell us what kind and what magnitude of sonic improvement we should expect to hear when we install an inductor in the safety ground position? I am wondering what all the fuss is about.
-
Quiet Earth,
For a system with properly implemented, balanced ICs, I wouldn't think it a noticeable improvement. My own system, fed from a single mains circuit supplied multi filter/outlet conditioner, and that dedicated circuit's outlet is 6' from my electrical panel, gives little opportunity for ground loop/noise and I have no such problems running single ended or balanced.
I have some hopes based on preliminary evaluations in show conditions, but I've not done the necessary measurements to form any real conclusions.
FWIW,
Paul
EDIT: spelig & punctuation
-
Reading your responses makes you sound like you have blood pressure problems from stress. You're not the first person to have an "attack" manner on here. - I don't think anyone isn't interested in what you have to say, but how you say it is what people are responding too. -
I am rather fond of how JN writes, safety is not an area where sugar coating can be applied. Then again, lots of folks consider me an asshole. 8)
-
Jimmy,
I suppose your experience with chokes is on significantly larger ones than those under discussion.
I work with itty bitty ones in signal circuits up to the 5 and 10 kA stuff.
A 1 inch, 1 ounce, 16amp, 4 mH choke is simply from a size perspective, absurd. I asked the Stateside Schurter reps about this a few years ago, positing that with a couple of milliamps running through it it measured its nominal inductance, but when presented with larger currents, it saturated, dropping inductance down to a equivalent air core inductor, presenting minimal impedance to do its job of clearing a breaker. Schurter's response was that indeed this was how it functions, but given language difficulties, I wouldn't use them without verification on my own.
Per Schurters own documentation -
http://www.elektronik.ropla.eu/pdf/stock/tim/de_deh_den_deno.pdfI believe the above refer to EN 138100 & EN 60938-1
I searched their site (edit:previously) but was unable to find that datasheet. (edit:reading the datasheet you linked to) and your inductance measure, to me, is a game changer, thank you. Discussion below.
Its actually moot as Schurter does not import the DEN/DENO-40 into North America and that's the only one with a wire cross section >= 1.5mm2. When one plugs a 15 amp plug, NEMA 5-15P, into an outlet, one doesn't know if the outlet is fed by a 15 or 20 amp circuit, so one should assume a 20 amp circuit.
Agreed.
While its relatively easy to repurpose available Stateside components to meet those requirements for a 20 amp circuit, given the tenor of the discussion, it seems unadvisable to discuss this.
I disagree.
The datasheet states clearly that their devices drop less than 4 volts at 4 times I nominal. This spec guarantees the two points I've been harping on. It assures us that the chassis cannot rise to lethal voltages should a fault to ground occur, AND it assures us that it will absolutely clear the breaker, quite possibly magnetically for either 15 or 20 amp breakers.
I no longer have any qualms about the use of this device on a specification basis.
The only point I believe needs discussion is how it is connected. NEC doesn't allow soldering as the primary connection method, and I agree with that based on experience. I've had to repair PC boards where the soldered through holes failed by cracking (edit:of the solder to pin near the top of the meniscus), most recently the control board to my house gas furnace ( in the dead of winter of course). Since this device bonds to chassis, I would recommend using a screw to bond one lead to chassis, and either the correct guage wirenut or crimp lug on the other lead. It is worth noting that I occasionally wire up a light fixture and find the wire ends prepped by solder dip from the factory. ABSOLUTELY DO NOT DO THIS FOR A SAFETY BONDING CONDUCTOR!!!! The solder will creep under compression, and will loosen up over time.
RDSU ,
While these ground chokes seem to have caused much contention, I'd like to thank you for bringing them up here on AC.
Regards,
Paul
I absolutely agree..very nice.
jn
-
I'm not sure how to explain the language you use, and how it comes off. But basically people can come to their own conclusions with more minimal information not including the caps-lock words (perceived as raised voice); no need to be so pessimistic. Reading your responses makes you sound like you have blood pressure problems from stress. You're not the first person to have an "attack" manner on here. - I don't think anyone isn't interested in what you have to say, but how you say it is what people are responding too. -
I will use caps, font size, and color to enhance the visibility of points I consider important. Safety is something I always stress at home, work, and online. I do not have blood pressure issues, so don't worry about that.
You are entitled to your opinion of course, and I thank you for it. I value it and listen.
If any of you can think of a good test experiment to seriously gauge how affective these are in a fault, I might be able to give it a worst-case scenario test. Maybe I'll come up with something, but I don't particularly believe there is an issue.
AC inductance tested vs 60 hz current. This can be trivially measured and graphed. Insert it into the hot conductor of a terminal strip, and plug in light bulbs ranging from 10 watts out to 1400 or 1500 watts. Plug in a bulb, let it settle roughly 100 milliseconds :green:, measure the ac drop across the device with a DVM.
It would be great if the manufacturer could present such a curve on an easily accessible link for all to see..But it would be even better on this thread if you could post the data. Between that, and some well constructed use recommendations, I see no other items to object to in using them.
jn
-
While I'm not trying to fuel the fire, I do have some actual data about the 16A/4mH Schurter DENO inductor in question. I ordered a few of them and lashed up a test jig last night and did a few simple measurements. I did this for my own edification but thought I'd share.
The jig is as simple as possible, a high current 15V transfomer fed from a Variac feeding a series circuit of the inductor and a 1R resistive load.
(http://www.audiocircle.com/image.php?id=85361)
I then used the Variac to generate various source voltages and measured the voltage at the source and load. Since a 1R load was used, the voltage across the load equals the current and Kirchoff's law says all currents must be equal in a series circuit, calculating the Z the of the inductor is as easy as can be.
First I measured the inductor with an LCR meter.
| DCR | 0.02 Ohm |
| L vs Freq | |
| Frequency | L |
| 100Hz | 6.78mH |
| 120Hz | 6.76mH |
| 1kHz | 6.68mH |
| 10kHz | 6.37mH |
Since the measured L was greater than the 4mH spec, the calculated reactance @ 60Hz for 6.78mH = 2.556
| VSource | VLoad | VDifference | I (Amps) | Inductor Z |
| 0.1 | 0.028 | 0.072 | 0.028 | 2.571 |
| 0.21 | 0.12 | 0.09 | 0.12 | 0.750 |
| 0.336 | 0.223 | 0.113 | 0.223 | 0.507 |
| 0.501 | 0.424 | 0.077 | 0.424 | 0.182 |
| 1.02 | 0.945 | 0.075 | 0.945 | 0.079 |
| 2.019 | 1.903 | 0.116 | 1.903 | 0.061 |
| 3.01 | 2.87 | 0.14 | 2.87 | 0.049 |
| 4.02 | 3.85 | 0.17 | 3.85 | 0.044 |
| 5.02 | 4.81 | 0.21 | 4.81 | 0.044 |
| 6.01 | 5.75 | 0.26 | 5.75 | 0.045 |
| 7 | 6.72 | 0.28 | 6.72 | 0.042 |
| 8 | 7.77 | 0.23 | 7.77 | 0.030 |
| 10 | 9.63 | 0.37 | 9.63 | 0.038 |
The short version is, above about 30mA the core starts to saturate and it becomes a low impedance device. This in no way takes away from the dangers of placing an impedance into a safety ground circuit! I am simply presenting what I measured. If my methodology was wrong, please correct me. It was late and I'm by no means an expert, just a semi knowledgeable tinkerer.
mike
-
Occam,
Safety concerns aside and just for academic clarification please,,, can you tell us what kind and what magnitude of sonic improvement we should expect to hear when we install an inductor in the safety ground position? I am wondering what all the fuss is about.
The ground loop forced upon us by safety allows coupling between the currents in the grounds and the inputs and outputs of the equipment. This is worst for unbalanced equipment, but it still exists in balanced equipment.
The equipment you can buy has not been adequately designed for EMC ( Electromagnetic Compatibility). EMC requires all currents into and out of equipment be controlled.
As a consequence, much can get into the signal stream depending on the physical size of the ground loop, and what magnetic fields can get trapped in that loop.
The biggest challenge actually comes from the equipment itself. Power amps modulate the AC line current based on the audio power delivery to the speakers, and that modulation is odd order harmonics on the powerline, and even order harmonics within the amplifier chassis. Also present on the line will be some of the actual music frequencies.
So when somebody says that changing a powercord or an IC, or even some widget like the devices being discussed here causes change to either the during-music background noise, or modification of the soundstage imaging, they may not be imagining itOf course, expectation bias also exists.. There are real engineering reasons for this type of coupling.
The easiest thing for a user to do is to try moving the IC's and powercords around. One solution that has worked well for me is to wrap the IC's around the power cord between the source and sink. I've only done this for unbalanced IC's up to 125 feet, so cannot say if it works for long lengths..
jn
-
I have a few diagrams in my gallery showing ground loop stuff, all are welcome to peruse it.
I'll answer all questions posed.
jn
-
Then again, lots of folks consider me an asshole. 8)
:nono:
:kiss:
:oops:
-
If my methodology was wrong, please correct me. It was late and I'm by no means an expert, just a semi knowledgeable tinkerer.
mike
Excellent design, excellent implementation, excellent data.
Poor wrap-up. I disagree with the descriptor "semi".. :thumb:
Thank you.
John
-
mgalusha, thanks for that small test. While I could get a lot of light-bulbs, I think I'm satisfied with that (again). Besides I was thinking more about breaker tripping scenarios, not inductance tests. Btw I'm fine with straight forward talk on safety, but you have to let people use information, not force it on them unless there are legal concerns because they are breaking code in public conditions; at which point you don't enforce it, someone else you contact does.
Note*: The DENO isn't made for being in the circuit mgalusha has it in, if anyone is reading this and curious. It basically doesn't work in that condition. It's meant for ground (earth).
*NEC only requires non-solder bonding, for electrical bonding (hard-mounted electrical wiring into a structure) which doesn't include a device you may add the DENO too. However, compression is a great idea in AC application considering the high current, and long term use. (I actually have my CMC/DMC's I use in power conditioner crimped and soldered, the DENO's are just crimped)
-
Excellent design, excellent implementation, excellent data.
Poor wrap-up. I disagree with the descriptor "semi".. :thumb:
Thanks John. :oops:
Note*: The DENO isn't made for being in the circuit mgalusha has it in, if anyone is reading this and curious. It basically doesn't work in that condition. It's meant for ground (earth).
Obviously but exactly how would you go about measuring the Z vs I? Please propose a viable alternative. Since you already have been using them and have not presented any data, I suspect you don't have one.
-
You're right, I asked for one :lol:
I was thinking something like wiring a smaller 20a breaker into a (much) larger one, then producing a load (fault) that would obviously trip a 20a breaker, and using the DENO in it. It'd take a little construction, it'd be empirical. It'd be setup and performed by an electrician that has very extensive experience with conditions that supersede anything ever mentioned on here. But I don't see the point in doing it since everyone has come to the conclusion that they are safe.
I assume someone else on here finds the progression of this thread amusing. "I trust code, and not the people selling individual pieces that have to meet code for importing and selling, but I do trust made devices that are certified with code stickers/silk screen" ...... "wait it's ok"
-
You're right, I asked for one :lol:
I was thinking something like wiring a smaller 20a breaker into a (much) larger one, then producing a load (fault) that would obviously trip a 20a breaker, and using the DENO in it. It'd take a little construction, it'd be empirical. It'd be setup and performed by an electrician that has very extensive experience with conditions that supersede anything ever mentioned on here.
A few points. Sounds like a reasonable test, you can use varying lengths of #12awg romex to change the fault current peak, like 2 feet out to 100 or so. Just be careful in breaker selection. Make sure you're using a 10 kiloamp rated breaker, and make sure the panel board rating is compatible with that. Industrial systems may not have the same bolted fault limit that a consumer home would. Utilities control the fault current max to homes, but set industry for best efficiency.
If you have a clamp-over current probe, you can scope and save the fault current to determine the peak.
But I don't see the point in doing it since everyone has come to the conclusion that they are safe.
Actually, the conclusion is that the reactive drop does not allow lethal voltages to be presented to the chassis as a consequence of core saturation. That is only one concern.
What cannot be concluded is the fact that they are safe in the application for 20 ampere breakers under various fault conditions. That is what you as a manufacturer should demonstrate prior to selling product. Positive test results would be a great selling tool. Negative test results help you immediately.
I assume someone else on here finds the progression of this thread amusing. "I trust code, and not the people selling individual pieces that have to meet code for importing and selling, but I do trust made devices that are certified with code stickers/silk screen" ...... "wait it's ok"
While slanting the progression of the thread with a skewed view may amuse you, the facts are different.
1. A reactive device was proposed to be inserted into a safety bonding circuit to eliminate ground loop problems.
Breaking into the safety ground and inserting a reactive component is extremely dangerous if the "fix" is incapable of clearing the breaker, dangerous if the chassis
potential is allowed to exceed lethal levels, and is dangerous if the integrity of the connection cannot be guaranteed for the life of the equipment.
2. A link to the device was given, and the data from the manufacturer did not indicate control of lethal voltages, only that it was a reactive device.
Further discussion ensued on how circuit breakers work, what criteria is needed for controlling chassis potentials, and how long the nominal reactances cited by the
manufacturer would take to clear typical 15 and 20 ampere breakers.
3. Further discussion on application ensued and test data generated by participants was presented.
A believed to be design feature of the device, extreme core saturation, limits the reactive voltage drop of the device to 4 volts when driven at 4 times the rated current.
4. Now it is being stated that the device is safe because the drop is 4 volts max at currents tremendously small with respect to fault currents.
The manufacturer does not present data in support of the device surviving fault conditions, nor how to connect it in safely.
Trust code? It is not a case of trust. It is a case of use but verify. I follow code as I wire a 10e+9 dollar machine and at home during reno, but I always examine the code and the application. Code updates every 3 years, and some of those changes are a result of people like me notifying the NFPA about errors we find.
Trust people selling individual pieces? Only if the pieces are certified for use in the application. The vendor's datasheet is severely lacking in fault current tolerance data (which is the defining parametric for this safety device), reactance vs ac current, ampacity curves for current vs time, and detailed direction on how the connections to the device should be made which remain safe for the life of the product.
Trust things certified with a sticker/silkscreen? That is the entire purpose of NRTL's. Verification that the product has been made consistently using a process and materials of known quality such that the product will provide the expected results. I expect that of medicine, food, airbags, and all my electrical equipment.
And there has been no "wait, it's ok."
Several hurdles have been cleared, but the race is only half over.
Trying to characterize safety concerns in a non engineered application of a safety circuit as ""much ado about nothing"" does nothing to support your reputation.
Solid engineering on the other hand, does. I hope you do the tests if you are going to use the product. I'm more than ready to assist if requested.
John
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I don't think anyone is using the DENO as a ground loop elimination device.
We can talk more when I get a breaker, or set one up for independence from the panel with the larger (10 kiloamp) breaker.
-
'Salis' that (10 kiloamp) is the breaker's 'Interrupting Rating'. That means when something really bad happens with the power company equipment and the high-voltage line gets connected directly to your house. Under these conditions, thousands of amps are flowing into your house. So this rating means that the breaker will still trip with all this current flowing through it rather than failing as a dead short.
-
'Salis' that (10 kiloamp) is the breaker's 'Interrupting Rating'. That means when something really bad happens with the power company equipment and the high-voltage line gets connected directly to your house. Under these conditions, thousands of amps are flowing into your house. So this rating means that the breaker will still trip with all this current flowing through it rather than failing as a dead short.
And? I'm just agreeing with jn that I'll use one that is rated for that. Most of them are now anyways. The larger one refers to the actual amperage rating for use and trip (in-circuit) that is exceeding the 20a test one substantially enough.
-
Oh, sorry. I saw that (10 kiloamp) number out of context and thought that you were talking about getting a huge breaker. If you have a spare breaker and a magnifying glass you might be able to read the very fine print for the 10kA rating. But I think that all the breakers that fit in your breaker box (panel board) have the same rating.
-
I don't think anyone is using the DENO as a ground loop elimination device.
Actually, that is the only reason to ever consider using the device.
The biggest problem caused by safety ground is the creation of a low impedance loop when independent components are hard wired together in an attempt to share a reference node for the audio signals. That loop is capable of trapping time varying magnetic flux being created by the AC delivery system and the system itself. Faraday's law of induction shows the reference ground wire will not have exactly the same potentials with respect to each other as a consequence.
The gist? Insertion of a reactance in the safety ground is NOT "conditioning" the AC power waveform, it is affecting the ground loop currents which can alter the sound of the system.
This device is only one type which is used in attempts to control that loop and the resultant current flowing in it. Misguided attempts at using 1 ohm or 10 ohm resistors, inductors, diodes to break the safety ground may solve the immediate concern of loop currents, but they compromise the safety of the system. From what I can see, this unit is the best I've seen for this function, but there is still work to be done.
The supreme requirement for the safety bonding circuit is for it to be totally effective for the life of the equipment, not the life of the owner..
We can talk more when I get a breaker, or set one up for independence from the panel with the larger (10 kiloamp) breaker.
I read this the same way speedskater did. That of a very very large circuit breaker with a remote operator to rack the puppy, and a Back to the Future "Darth Vadar from the planet Vulcan" suit. I guess we are all on the same page now...the 10 kiloamp rating is the surge the breaker is supposed to be able to survive without a containment failure (blowing up). The standard is consistent with what the power company will allow into the residential system, so that there are no arc flash incidents.
I recommend the test be performed using a 20 ampere breaker mounted into a 200 amp residential loadpanel. I suspect this is one of the larger service panels used in residential application.
I do not know what the European utilities set as the maximum fault current that can be delivered to a residence there, so cannot say if the design is adequate for US residential 20 amp breaker time/current curves. I also do not know if the saturation breakpoint is sufficiently high for use in pro equipment, as Whitlock has measured AC ground loop currents at up to 58 milliamperes AC. Use of these devices in that environment would render the low current isolation ineffective.
jn
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When does the 2mh version (25a) saturate? It might be better for places like studios and what not.
Getting rid of loop noise is good, but so is eliminating anything not 60hz. Ground noise has been associated with making a difference on digital equipment. (I don't think we should get into this too much right now)
My dream Halloween costume is an authentic Darth Vader costume but... I've got no interest in close exposure to things like electrical flashes given that within a certain proximity no suit, Sith or not, will stand up to it.
200a is a good sized one in the US. Give me a few days to see what I can organize.
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When does the 2mh version (25a) saturate? It might be better for places like studios and what not.
If one assumes that the inductance is proportional to the number of turns squared and they use the same core, then half the inductance would require 70% of the turns. (1/sqr2).
The magflux is proportional to NI, so the current required for the same effect would go up as the square root of 2, or 1.414.
But remember, the idea is to lower the ground loop current. Lowering the inductive reactance of the element will raise it. You want higher inductance, but you want that higher inductance component to still survive operation under the upper line of the breaker clearing curve.
Getting rid of loop noise is good, but so is eliminating anything not 60hz.
I have already detailed ad nauseum the concept of odd harmonic modulated and non modulated haversines and music content making it into the ground loop and coupling to the signal path..that is all non 60 hz.
My dream Halloween costume is an authentic Darth Vader costume but... I've got no interest in close exposure to things like electrical flashes given that within a certain proximity no suit, Sith or not, will stand up to it.
Ah, some explanation. In the Back to the Future second film, Marty wore a 40 cal rated arc flash suit, called himself Darth Vadar from the planet Vulcan. The suit is rated for an electrical flash at the 40 cal level.
200a is a good sized one in the US. Give me a few days to see what I can organize.
Me, I'd just go home to do it. Seems you're going to sell the product, eh?.
Good luck in your endeavor. Be careful.
edit: I graphed mgalusha's data log-log.
(http://www.audiocircle.com/image.php?id=85511)
jn
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Reactance value at 60hz, direct information from the factory.
DENO-25-0001 and DENO-40-0001 => 1.5 Ohm
DENO-23-0001 => 0.75 Ohm
They also noted zero concern with breakers.
Inductance they are rated at goes from 50-300khz.
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Reactance value at 60hz, direct information from the factory.
DENO-25-0001 and DENO-40-0001 => 1.5 Ohm
DENO-23-0001 => 0.75 Ohm
They also noted zero concern with breakers.
Inductance they are rated at goes from 50-300khz.
Good Grief! Are you impressed that Schurter knows how to use a reactance calculator?
Direct information from the factory?????
http://www.electronics2000.co.uk/calc/reactance-calculator.php
put in 60 Hz and 4 mH and mirablie dictu! you gets 1.508 ohms
They also noted zero concern with breakers.
Who cares?
The ability to find a reactance calulator and plug in numbers doesn't merit credibilty on safety issues in North America, that, and the fact that only the DENO-40, which isn't imported to North America, would be their only offering rated to 'clear' a breaker from a faulty 15 amp appliance plugged into a perfectly ordinary 5-20R outlet, as defined by their own documentation. FWIW, YMMV
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Relax Occam. I'm not "impressed". That's just what they replied.
If anything I'm disappointed that they didn't give details about how they react in a fault in this reply. But I can say that without any word of caution or concern they are fully liable for fault of a properly used DENO. That is important, too.
A test is still in order. It'll happen.