That is a good point. Seems like a lot of people get touchy whenever safety ground is brought up. It would take a super duper winning the lottery kind of freak accident to put mains voltage onto the chassis in the first place and on top of that another kind of freak accident for it to find a path from one hand touching the hot to the other hand touching a ground or return wire for the electricity to flow through your chest (or some other variation of death dealing electrocution) before something in the panel tripped.
I'd be a bit more concerned if here in the US we dealt with 240V but I don't see the big deal here nit-picking these "what if lightning struck the same place 3 times in a row" type scenarios.
Ground loops are sometimes an absolute nightmare of a situation and I think whoever first thought of the bridge rec solution was as clever as it gets. It's a great idea.
What I notice is that counter culture is talking about voltage...
counter culture:
No. What we're interested in is minimizing the return loop area. If the AC voltage on the +ve rail is coupled onto the -ve rail, it will return to the PSU, if the -ve rail presents the most favourable path.
...and jneutron is also talking about voltage (in an amazing way):
jneutron:
An AC voltage does not couple to another wire when they are twisted, unless you count tens of picofarads...
You can tell jneutron is talking about voltage by the way he says voltage.
Actually I'm willing to say that jneuton misspoke in some way. Heck, I've written long articles, only to discover later that I was thinking of something else entirely.
But I'm not willing to say that dogged adherence to a questonable theory indicates expertise. All the experts I've known go hmmm when presented with other theories, and immediately start thinking the whole thing over.
.
let us up the ante....
how sure are we that your electrical contractor followed the electrical code correctly?
when installing your electrical sockets......
how sure are you that in your socket outlet, the line is line and neutral is neutral?
how do you know that your system is a line to neutral one and not a balanced line?
you can follow Bonsai's scheme and still come up short....
rfi ac is contemplated here....60z ac has no effect afaik...
We ran 3 dedicated lines, 2- 30A and 1-20A. I make sure they are right. The outets I run anything important on are also checked. I have climbed in the attic and crawlspace more times than I'd like to remember. I pay attention to what the builders did while I was there though. Not trying to argue though just sayin'.
I think your point is an important one for members who might not think about giving the projects they build proper clean juicy AC goodness. And of course if your place isn't at least wired to code it is unsafe.
I think your point is an important one for members who might not think about giving the projects they build proper clean juicy AC goodness. And of course if your place isn't at least wired to code it is unsafe.
A very good point: risk needs to be recognized and properly managed. I have had electrical work done 5 times now in my 1927-era house, each time to upgrade/replace existing elements of the electrical system, or add capacity or lines, and new circuits. I specified commercial grade or industrial grade switches, outlets, GFCIs, and in-wall surge protectors, as well as a large Hubbell whole-house surge protector (with LED monitor indicators). I was lucky that my entire house had been heavied-up and rewired within the last 25 years (just before I purchased the house) and therefore subject to strict County inspection. Each time I had electrical work done, a permit was pulled, the electrical contractor verified proper wiring, and it was re-checked on a sample basis by the County inspector. I have also verified a sample of my lines - including ALL of my sound system outlets - with a 3-prong plug-in checker that I purchased at my electrical supply house. I feel comfortable saying that my wiring is correct, and therefore I also feel comfortable adding the ground isolation network to any amplifier that I build.
If one's electrical system has not had the same level of quality components installed and verified by multiple players as mine, I think that the risk of failure (and death or serious injury) is much higher. Thus, each individual MUST be responsible for evaluating their electrical system and determining whether they are willing the accept the risk. There is no shame in deciding not to accept the risk for oneself; but also recognize that your determination is a personal one and may not be relevant or valid for someone else.
Geary
And you can tell when I'm talking about current, by the way I say current.
You're confusing transformers which use ampere's law and faraday's law of induction to generate voltage with a twisted pair that is capacitively coupled.
I have not mis-spoken, I do indeed understand E/M theory, application, design, and test. I do it for a living, and have done so since '81.
You do not understand the theory. Are you saying that your dogged adherence to your inaccurate understandings is or is not "expertise"?
jn
Can you possibly be serious? You seem to keep insisting that adjacent conductors are not inductively coupled. In which case, no matter whose name you drop, transformers no long work, nor do electric motors, nor does civilization as we know it.
But who am I to argue with an expert. Have it your way, transformers don't work. At least, as before, the "loop area" question is settled. Turns out there's no such thing.
Stunned by these revelations I leave the matter in your hands.
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Take a twisted pair of wires and pull on the ends of one of the wires to stretch it. You will find that you end up with is a straight wire with another wire coiled around it; this is a way to simply the geometry of the problem.
Now, although the coiled wire does indeed produce flux when a current passes through it (i.e. it is an inductor) the flux flows harmlessly in parallel with the straight wire and therefore induces no (or negligible) EMF in it. Thus there can be virtually no transformer action in a twisted pair.
Current can flow from one wire to the other through the capacitance between them, of course, but that is not transformer action.
do you have actual data as to the number of folks killed?
it seems to me that you and your kind seems to go around forums scaring people...
makes me wonder if you and the likes of you are really into building anything at all....
in my over 40 years of experience not single episode of this, so....
no one, because transformers can be well made, besides a failed transformer will smell, will blow fuses when in circuit and let the magic smoke out if the fuse did not blow first....
seems to me like folks like to see dragons where there is none.....
we can not stop them from posting here...but how to undo the damage they have done?
I've built hundreds of pieces of audio and other equipment. After having seen right in front of me an unthinking student cut through a live 480VAC wire,
there's no doubt in my mind that it's best to scare the hell out of people so that they'll be careful. I certainly wouldn't want someone's injury or death
to be my fault or haunt me the rest of my life. I hope that most others here feel the same way.
e
again, how many have moved over to Bonsai building guide?
bentsnake as the OP needs information....whether he accepts it or not is not is no longer your problem....
I have high regards towards Bonsai, he is one DIY'er with plenty to show for it, his projects are all over this forum for all to see....
I also need to point out that his grounding scheme was the result of Leach's writings at the AUDIO magazine in to 80's.....
Like Leach, i respect Bonsai because he practices what he preaches...
again, how many have moved over to Bonsai building guide?
bentsnake as the OP needs information....whether he accepts it or not is not is no longer your problem....
I have high regards towards Bonsai, he is one DIY'er with plenty to show for it, his projects are all over this forum for all to see....
I also need to point out that his grounding scheme was the result of Leach's writings at the AUDIO magazine in to 80's.....
Like Leach, i respect Bonsai because he practices what he preaches...
electricity kills, no doubt....even today i am still scared each time i power up a new built equipment even though i know i took steps to keep murphy out...
in my over 40 years of experience not single episode of this, so....
no one, because transformers can be well made, besides a failed transformer will smell, will blow fuses when in circuit and let the magic smoke out if the fuse did not blow first....
seems to me like folks like to see dragons where there is none.....
we can not stop them from posting here...but how to undo the damage they have done?
With all respect, your personal experience is not representative here. These accidents happen even with industrial manufactured equipment - look up statistics. Don't forget that these Amps are staying in your livingroom, where children or friends may be playing...
By the way, i don't think that any damage has been done here by anyone.
Especially if you are working on open chasis with 230V equipment, you should always use some safety means like: Never work alone and always use a safety isolation transformer.
It may even save your live to work with ONE hand only, so that current can not flow through your heart..
Class-I is widespread in the DIY community because of its simplicity.
So i strongly argue to keep it stupid simple: Connect ANY accessible metal part with safety ground firmly - especially if you are not sure what you are doing.
(btw., ESFI speaks of 60 electrocutions and 30000 not fatal shock accidents in North America last year)
I think that this discussion is not going to any end and i will quit here. There are already some good and working schematics how to build a working audio ground for the people who are interested and who can read. Any further advice depends strongly ont the real amplifier layout and without measurements it does not have merit do go any further.
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