There are limits on leakage currents patients can be exposed to.
https://www.ecri.org/Resources/In_t...ectrical_Safety_in_Healthcare(TechNation).pdf
In something like a large scale Radiation Oncology system, most parts of the system cannot expose a patient to leakage currents. Thus for most parts of the system normal industrial environment safety codes are applicable.
Of course there are other potential hazards, such as dosimetry systems, treatment control systems, interlock systems, unintentional exposure to ionizing radiation, proximity to large moving equipment, etc. For one example, there was a robotic radiotherapy system that was found could under some circumstances potentially take a shortcut through the patient's body at high speed. Fortunately no one was hurt before it was discovered. In summary, there are all sorts of things to worry about besides electrical safety. They are all taken seriously.
Getting back to ground loops in consumer audio, the standards tend to be a little less strict than for medical devices a patient could come into contact with. IMHO it is a reasonable compromise between safety, performance, cost, etc. Absolute safety is not possible. There has to be some practical balance between competing goals.
Characteristic impedance of power cord ruining amplifier transient response?
Show me some measurements instead of marketing blabbering at 110 dB level.
My God, how those marketing people can shamelessly lie.
Thanks for the response! I hadn't come across "haversine" until you mentioned it in another thread, but then I'm not much of a mathematician!
Apparently, the haversine formula...
![\[ \mbox{haversin}(\theta ) = \sin ^2(\theta /2). \]](https://plus.maths.org/MI/9d3bf34c0d510ad4d77edb2882c058c8/images/img-0001.png "\[ \mbox{haversin}(\theta ) = \sin ^2(\theta /2). \]")
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...is used in navigation to calculate the distance between two points on a spherical model of the Earth along a great circle arc.
Although the trigonometric function is also used in electronics, I'm not finding a reference to its use other than it can be extended to the world of imaginary numbers.
Just a little diversion! 🙂
Are there non-Listed tie wraps?
Do those non-Listing companies pay dues to NEC?
Lately (recent decades) it seems NEC can be lobbied to be "protection" for its corporate members.
OH PLEASE
Relentless shill , unless the justification is "brain damaged" in which case we might tend to forgive.
NO normal Forum Member gets this OBSESSED.
I've no idea. I never thought about it. When I got the new 2023, I quickly reviewed article 392 and poof, there it is.
Might be a flame thing, where the tie wraps are not allowed to drip burning droplets as it gets hit with the flame, the vertical flame test stuff.
Reminds me, just had a romantic dinner by the fire last night.
Unfortunately, it was in my kitchen... and the fire was in the toaster oven..
John
All this chatter is like religion, a matter of faith, but the unsuspecting should not be fooled by all the technical musings, speaker connection cables definitely DO NOT IMPROVE THE SOUND and neither do power cables to filter "impurities" .
Well-constructed power supplies take care of the latter, and speaker cables - if they are of the length and thickness recommended by the respective tables - will give the same sound as high-priced esoteric cables.
As I mentioned before, this theme is part of audio snake oil, and one of the most venomous. Careful !
Well-constructed power supplies take care of the latter, and speaker cables - if they are of the length and thickness recommended by the respective tables - will give the same sound as high-priced esoteric cables.
As I mentioned before, this theme is part of audio snake oil, and one of the most venomous. Careful !
Attachments
Hmmm. USA cords. Made in the USA, or bought offshore from another facility and sold by a USA company to save money (actually, maybe to stay in business).
When some operator has to spot weld or crimp ten cords per minute for 8 hours a day, does everybody believe every cord is perfect?
I would not think so.
Saw someone mention the molding plastic holds the wire to the blade... Really? Someone seems to be guessing here without knowledge of the manufacturing processes used.
jn
Dat be da one.
A compression contact using overmolded plastic to hold it in contact just doesn't happen. The final contact area after plastic injection is just meaningless.
I can certainly see a QC issue with a spot welder or ultrasonic welder setup to bond wires to blades.
Just autopsied two (name brand) molded circuit breakers that failed, we've roughly five thousand in use. (I got to play with my mill again, and I got paid to do it..life is good.)
One was a 20 amp 3 phase, one was a 30 amp 3 phase. In both cases, the spot weld between a stud and the beryllium copper (I think) failed. It worked for maybe 5 years, eventually let go during a maintenance procedure.
Both were the same date code. Both breaker sizes use the exact same parts for that welded assembly. The only difference between the two sizes is the number of turns on the magnetic actuator, and the thermal element. I bet it was the same operator, same day, and probably something amiss with the welder or fixturing. (Or even the cleaning process prior to welding. Some parts are sized to thickness through rollers, and the mineral oils used in the rolling process can embed into the grains of the metal, preventing a good weld.)
Over-reaching blanket statements really do not help, that's why I posted.
jn
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A big worry is the grounding connection crimp.
If the ground lets go on some portable equipment, the IEC filter can bring the metal surfaces up to some intermediate voltage.. When somebody feels the tingle, or even slightly more than a tingle, it goes all the way up to the top of the "ladder" so to speak (some building in Washington DC). Days spent in shutdown, review specs, attend meetings, endless safety lectures...
That's why I started (preemptively) testing all bonding and leakage currents. So far, I've found 8 or 9 bonding problems, either a loose screw, a bug nut tightened over insulation, and even cases where they tightened a screw on a #2 stranded wire and the wire just flattened down and got loose.
Luckily, they are hiring an Electrical Safety Engineer, and with luck he can take over this stuff.
Jn
OMG. I stopped at 5 minutes in. My body could not decide whether to vomit, or laugh hysterically. It was so much fun watching that, thank you for that link.
I never would have thought that characteristic impedance could be eliminated. Holy mackeral.
I feel so good knowing that I can get up in the morning and look at myself in the mirror. How Garth can say things like that with a straight face, I cannot comprehend.
Again, thanks for that link, it was quite entertaining, kinda like a "who's on first, what's on second, I don't know on third" kinda thing.
BTW...mention of the "miles and miles argument with the last meter being important" is a real thing. Not because the electrons are tired or dizzy.. But because the power cords are all referencing ground at the outlets. If the power cord transient current delivery affects the sound of an amplifier, it's time to get a new amplifier. If the powercord geometric construction affects the ground loop impedance between components, that is a real EMC thing.
John
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Any thoughts on how we could DIY something like this? Big Jay says it is the best power conditioner.
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