[jneutron]

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

[jneutron]

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

 


 

[jneutron]

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

[Speedskater]

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.

[Occam]

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

[Folsom]

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.

[Speedskater]

I would think that for most of us, codes, rules or tests from:
UL
CSA
ETL
NEC
TUV
or
IEC
will apply.

[Occam]

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! 
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!

[Folsom]

Aaaarrg! 
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.

[Quiet Earth]

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.

[Occam]

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

[mgalusha]

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. 

[jneutron]

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

[jneutron]

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  , 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

[mgalusha]

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.


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

[jneutron]

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

[jneutron]

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

[jtwrace]

Then again, lots of folks consider me an asshole. 

 

 

[jneutron]

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"..

Thank you.

John

[Folsom]

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)