I'm always reading about the dangers of lifting ground from a power cord, especially in manufacturer manuals. Does this only apply to lifting ground from a grounded cord or just using an ungrounded cord, period? There are tons of devices in our homes that use ungrounded power cords (think wall wart). How is it possible that my house has not erupted into a ball of flames yet?
Anyway, I have a 2-prong power cord with a 3-prong IEC female end that came with my Luxman amp. I am getting the outboard power supply for my Calyx 24/192 DAC, but it requires an additional power cord. The Luxman cord sounds pretty good so I want to use that instead of spending another $500 to buy another one, which is +150% of the power supply itself!
The danger is getting shocked, not bursting into flames.
Wall warts and many other devices have plastic cases so even if the case contacts the line voltage you can't get shocked so they don't need the ground.
If it came with a three prong plug then safety standards dictate it should be there.
Herman, my Japanese amp came with this power cord that has a two prong male end and three prong female end. Since it was manufactured this way does that mean the cord is safe? Japanese household electricity is only 2 prong. Is there something about their electrical grid that is inherently more safe so that household devices don't require a ground plug? Is there something about Japanese electronics that make them more safe? Also, why the heck does a Japanese amp have a three prong female end when they don't have any three prong outlets? I know mine was converted for American 120V, but pictures of Japanese 100V show the same IEC plugs. There are lots of American devices other than wall warts that use 2 prong plugs that aren't necessarily plastic. A floor lamp comes to mind. If it is so hazardous to use an ungrounded power cord then why isn't it required for ALL electrical devices in the US?
Anyway, a 5V output DAC PSU doesn't strike me as a high powered device so I think I will just take the risk.
"Typical stereo electronics will (probably) not kill you if somehow a short develops to ground."
It is not short to ground but short to case, that we worry about and we (probably) don't want to be killed.
"The real exception is tubed electronics, and Color tube TVs. Both carry fatal voltages inside, and should be treated with respect.
Any 110V device carry fatal voltage inside and should be treated with respect.
"And no one does not have to be worried about items with only a two prong plug."
You have to be worried if equipment was designed to be used with three prong plug. Two prong plug devices are designed differently (plastic case or metal case separated by plastic inside). Converting device designed to work with ground prong (isolation class I) using cheater plugs is unwise and dangerous. Recommending it to others is even worse.
Kijanki is correct on all points. Elizabeth, as usual, gives incomplete and/or bad advice.
Eugene, I really can't say how equipment designed for the Japanese market is configured, but the use of a ground connection (3rd prong) to a metal case is inherently safer than one without. I remember growing up in the 60's before 3 prong plugs and ground faults were common and we would get shocked when we touched the metal washing machine in the basement while standing barefoot on the concrete floor. My dad had an electric drill with a 2 prong cord and a metal case and you could get shocked if you touched it and something grounded like a water pipe.
That doesn't happen these days with better designs and better safety standards that involve plastic cases and/or grounded outlets. Using a cheater plug to defeat the ground can be dangerous. Note I said "can be". The problem for those who do it is they usually have no idea when that is.
One could go technical with requirements (double insulation, clearances, leakage currents etc), but why? Take Herman's sound advice "If it came with a three prong plug then safety standards dictate it should be there" Logical and simple.
You can play with ICs, speaker cables etc. but this (safety) has to be done by the book.
I guess even if the amp is safe to use with an ungrounded cord, they might put a 3-prong inlet for use with all of the other aftermarket power cords out there.
So the moral of the story is: It depends on the device. Stick to what it came with.
Yes, you will very likely die. In 1987, my cousin burst into flames when he plugged in his ungrounded Technics TR19 tape deck. The manual clearly warned the user about this, but he was one of those "I don't need the manual" types. Don't become a statistic, and use caution whatever you do.
I personnaly would not float ground for equipment designed to be grounded, especially very expensive equipment. Why take a chance? I may take a chance for a cheap CD player, receiver, or anything else you will not cry about later should it go up in smoke.But, tube amps, tube preamps, any SS device worth a few bucks, phono stages, and phono stages are in my opinion not worth experimenting with to test AC issues or theories.
For years now I have used a grounded powercord w/my tube amps & used an ungrounded cord (cheap but very effective Volex cord w/the grounding pin cut off) on my CDP. The CDP is still grounded thru the interconnects to the amp & provides quieter better sound.
I lived in Japan for 9 years and was an audiophile at that time, so I purchased several Japanese components, all of which had two prong plugs. I did not understand why at the time but reading this thread taught me the differences, so thanks to all who helped me get less dumb. I am wondering about the question around the amp IEC having three prongs on some of the Japanese stuff though. I'm wondering if a power chord with a three prong plug is used with these components would the ground plug be functional? As someone said the Japanese electronics are built with plastic or coated to avoid the need for a ground in the chassis, but I wonder if the female plug on the back has any ground function, or if it is simply there to allow use of aftermarket cords. One might gain a false sense of security if they attached a grounded cord to an amp that had a non-functional ground.
Purely a guess but I agree with the idea that the Japanese stuff comes with the standard 3 wire input jack to be just that; standard. Those who like to play with power cords would shy away if they couldn't do that.
I'm guessing if they have a ground there, it is for a reason.
Someone above mentioned it will ground through the interconnects to your other components, and this is not necessarily true. Some equipment has the interconnects isolated from the metal chassis or case. So, don't think this will take care of it.
Some equipment may also have a capacitor/capacitors or other semiconductor connected from a hot 120 volt line to help reduce line noise by tying that hot line noise to the ground, or case that had a ground. If any of these parts shorted, there can be a possibility the case will have the full 120 volt line voltage. Plus, any other part mechanical failure can cause a risk, if it happens.
If this would happen, you could have 120 volts between this to any ground, or your other equipment right next to this unit, with the ground removed. In other words, yes, 120 volts between your amp and preamp, or any other equipment. Also, to any ground your on, or any other conductive item you may touch.
In my opinion, removing any ground wire that was there always has a risk.
Anyway, I have a 2-prong power cord with a 3-prong IEC female end that came with my Luxman amp. Eugene81
That is just one of the problems with IEC connectors. For some reason here in the USA IEC connectors have next to no safety standard rules/requirements.
Only power connector I know of used in the USA that has a piss poor contact pressure connection.
Same connector can be used for 120 or 240V applications.
You can buy a cord with a 20 amp female IEC connector with a NEMA 5-15P 15 amp plug on the other end. Can't do that with a NEMA 5-20R female cord body and a NEMA 5-15P 15 amp plug on the other end.
Definitely can not buy a cord with a 3 wire NEMA 5-15 or 5-20 female receptacle on one end with a two wire plug on the other end.....
So basically IEC connectors are not idiot proof because of the lack of a recognized safety standard. You can damn near do anything you want with the thing.
Anyway, I have a 2-prong power cord with a 3-prong IEC female end that came with my Luxman amp. Eugene81
That cord should not be allowed to be sold in the USA. Just for the reason of your post. Someone using the cord on a piece of equipment that requires a cord with a safety equipment ground... End result, same thing as using a ground cheater.
Why did the designer/manufacture of the DAC power supply decide he wanted a safety equipment ground for his equipment? You could ask them. It could be he didn't want to spend the extra cost for the double insulated power wiring, or maybe it could be a design thing.
If you still have the Luxman amp check the back of the unit's IEC male connector. I would bet it only has two blades, the hot and neutral. No safety equipment ground blade. The Luxman amp uses double insulated power wiring inside so it does not need the safety equipment ground.
That is a universal 100-240 switching supply. Since outlets in many countries don't have a 3rd prong for ground it would have to be designed to not need one.
Anyone using ungrounded power cords will die eventually. Alas, so will those using grounded ones. That said, as Forrest Gump remarked "Stupid is as Stupid does"; I have known a fair sample of the shallow end of the audiophile pool and none of them have yet succeeded in hifi Hari Kari despite their best efforts. The prize probably went to the guy who built a large outboard capacitor bank, charged it up, unhooked it without discharging it and then tried to hook it up again. He also liked to leave the cage off his EAR 509s despite the presence of potentially lethal voltage. They looked better that way.
That is a universal 100-240 switching supply. Since outlets in many countries don't have a 3rd prong for ground it would have to be designed to not need one. 01-28-12: Herman
Herman,
You could be right..... I checked the Net for an owners manual for the unit with no luck. Maybe the OP will chime in and let us know what the manual says.
I did look at the link you provided and noticed the picture of the back of the unit shows the male IEC connector has the safety equipment ground blade contact.
I have no way of knowing if the PS is Listed by a recognized safety testing agency for use in the USA. (Such as UL)
Just curious about your thoughts,... if the PS uses an IE transformer with an electrostatic shield that is connected to the metal chassis, enclosure, of the PS and the equipment ground contact of the IEC connector. If the ground is floating will that have any effect on the EMI/RFI rejection performance of the PS?
I can say that style of male IEC connector can be purchased without the ground blade contact.
To go back for just a second to the OP's Luxman amp, the manufacture should have supplied with the amp , at least for sales in the USA, a 3 wire plug PC with the IEC grounding type connector. That way the cord would be idiot proof and could be used on IEC fed equipment that require the use of a safety equipment ground.
Just one example, that is how the Arcam Alpha 9 CDP was designed/manufactured. The unit has the universally used male IEC connector with only the hot and neutral blades. No safety equipment ground blade. The unit uses double insulated power wiring.
The cheap OEM power cord the came with the unit is a 3 wire grounding type. The ground wire is not used in this case but if for some reason the cord was just thrown in a box and later found, there would not be safety issue if it was used on a piece of equipment that was intended to be connected to an AC grounded system equipment safety ground.
The risk of death or injury from floating a ground is so low it is not a practical concern.
I apologize for my previous comment. 01-29-12: Herman
Sorry, to broad of a statement.
If the OP's cord in question was used on a home computer in a basement with a bare concrete floor and for some reason the user was in his/her bare feet it could become an issue.
Plain and simple the cord is not idiot proof. There is a reason for electrical safety standards. Yes they can be defeated. And if the user chooses to do so he/she then takes that risks if any.
But how about the person that doesn't know there could be a potential safety problem with using the cord.
That is why NEMA standards makes sure the square peg will not fit in the round hole.
Just curious about your thoughts,... if the PS uses an IE transformer with an electrostatic shield that is connected to the metal chassis, enclosure, of the PS and the equipment ground contact of the IEC connector. If the ground is floating will that have any effect on the EMI/RFI rejection performance of the PS?
What is an IE transformer?
If the shield is tied to the neutral and the neutral line is tied back to earth ground I'm not sure if the lack of the 3rd line makes a difference, but I don't think all countries use polarized plugs with the neutral tied to earth. Interesting question but I'm not familiar enough with power around the world to answer it.
If the shield is tied to the neutral and the neutral line is tied back to earth ground I'm not sure if the lack of the 3rd line makes a difference, but I don't think all countries use polarized plugs with the neutral tied to earth.
And that is why the shield shall never be tied to the neutral conductor. Reversed AC polarity would make the shield and the chassis hot.
The neutral is a current carrying conductor and should never be used as an equipment grounding conductor.
Per NEC code The Neutral conductor shall be connected to earth ground at service entrance and at no point there after.
Interesting question but I'm not familiar enough with power around the world to answer it.
How about just here in the US? If the shield was connected to the chassis and the ground contact of the IEC and the equipment ground was floating would the PS enclosure act like an antenna?
Also what are the chances the B- of the DC output of the PS is connected to the chassis as well?
I understand where you are coming from but don't know enough about the power grid and design to say one way or the other.
I do know that a switching supply that doesn't use a transformer could get hooked up so the hot side of the AC line was connected to the output so I have to believe that type would never be used in a device sold to the public.
The more conventional way is to take the incoming line voltage to drive a circuit which jacks up the frequency much higher so you can then use a much smaller transformer that isolates the line from the load. There is no metal chassis so nothing to isolate.
I don't know enough about how these switching supplies generate RF and interact with the incoming line and how they radiate to comment further.
However, I am interested so if you come up with any more info please share.
Total number of people killed from home stereo, TV etc. is about 3 per year.
www.cpsc.gov/library/shock95.pdf
Chance of 1 in 100 million is not big but remember that ones who died had most likely something wrong with the wiring or grounding. What percentage of people have wrong grounding? Most of people buy equipment and don't modify it or use cheater plugs. Let say that one percent has wrong wiring or no grounding. Now your chances of fatal accident got 100 times higher - 1 in a million. Take into account that it is amount per year and we like to be alive for, let say, next 50 years - now your chance is 1 in 20 thousand. It might be still small but you would be ecstatic to play lottery at such odds. Don't play lottery with your life.
I have another problem with this attitude toward safety. I might be ignoring safety here and there, but would never ever tell anybody that it is OK to do so. That would be irresponsible and stupid of me. Would you recommend to your friends modifications to their car braking system claiming that only one car in so many millions have accident from malfunctioning of the brakes? No because it would place them in danger.
As for floating shields - they should be grounded. Non magnetic shield protects from electromagnetic pickup by means of skin effect. It means that current is induced, since non magnetic shield cannot stop it, but travels on the outside - shield because of skin effect. Equivalent field in the center of conductor is zero. Shield has to be grounded for this to work. At lower frequencies skin effect stops working but cable is too short to become effective antenna (below 1/10 of the wavelength).
Switching power supplies generate noise but it is noise at high frequency easier to filter out than 120Hz. For that reason Jeff Rowland uses switching supply in Capri preamp where efficiency is irrelevant. His newest class AB power amp model 625 has 1MHz switcher. It is difficult to say what a switcher is because every linear power supply is switching power supply operating at 120Hz where width of the current spikes is load depended. Properly executed SMPS switches at zero voltage/zero current and can be very quiet but they got bad rap from poorly designed cheap computer supplies. Don't forget that linear supplies are unregulated while SMPS are line and load regulated. http://jeffrowlandgroup.com/kb/questions.php?questionid=145
Herman, I'm not sure of that. Chances of being struck by lightning are pretty similar 1 in 1 million but people still take safety precautions, golf courses are being evacuated, sport events outside suspended etc. Again - chance of one in 1 million is in any given year. In your lifetime you have at least fifty time higher chance - 1 in 20,000. I don't go outside during lightning knowing that most of people killed ignored danger - like teenager in my area who kept playing soccer in forest preserve during thunderstorm or people sailing in spite of weather forecast and warnings. For the rest of people, who take precautions, chances are practically none - meaning that chances for people ignoring danger (a few) are very high - much higher than 1 in 20,000. One could say that stupidity kills.
ILLOGICAL PEOPLE DIE FIRST. I cannot control cancer or nuclear attack but can greatly lower chances of being electrocuted by not playing in the park during thunderstorms or cutting ground from my electrical equipment that was designed with this ground as a protection. I would not recommend bypassing safety features and am very surprised that people without degree or any education in electrical engineering dare to make such recommendations. Do you also recommend to disconnect airbags? Just curious.
If it is such a danger then why are PS Audio power cables made with a ground plug that can be unscrewed? I have been floating mine of years [30?] when it would help. Just exactly what does the "ground lift" switch on equipment do? I had always supposed it lifted the ground; how is this different from floating it? A tempest in a tea pot.
Stanwal - I don't know about PS Audio but suspect that they design their units such way that it doesn't need grounding (class II) but ground is still provided to reduce noise pickup. I suspect that it is the same principle with ground lift - otherwise it would be illegal to manufacture such thing. Every user guide has at least one page on safety precautions. You can also call PS Audio and ask them.
Inna, not sure how you interpreted my post that way, but I am definitely not asking for advice on how to get electrocuted!
I think I'll take my chances on using the Luxman cord with the DAC. I will probably upgrade in the next year or two anyway. I'll just put a piece of masking tape on it that says "TOUCH CASE WITH INSULATED SCREW DRIVER BEFORE HANDLING!!!" in big letters. How about that?
In my apartment circa 2005 ALL outlets were groundless and needed cheater plugs. Is this illegal? (California) If not, why would that be allowed if potentially lethal from everyday use? My guess is the worst that would happen is getting "zapped" as aforementioned (never knew that used to happen... crazy), but nothing life-threatening.
And you, Elizabeth, are afraid of EVERYTHING because "EVERYBODY is afraid of whatever" and you can't help but feel for everybody. Seemingly paradoxicaly you still live in America, or is it America lives in you? Did I help you understand why you have to listen to music all the time? And your preference for a very clear sound means that you need to figure out what the hell is going on. Let me tell you this: nothing is really going on, just the usual weirdness.
In my apartment circa 2005 ALL outlets were groundless and needed cheater plugs. Is this illegal? (California) If not, why would that be allowed if potentially lethal from everyday use? Eugene81 (System | Threads | Answers | This Thread)
I believe it is. It states it started in 1962 here. Link[http://www.electrical.com/national-electrical-code/]
Yes, you will die a long,slow, agonizing death. The whole time you are dying you will be hearing the answers to this thread over and over in your head(that's the agonizing part,the long and slow is BS!!).
Kijanki, PS Audio power cords are used with every conceivable type of gear, not just PS products; are they ALL designed not to need grounding? The point is that they [PS ]say that the sound is better sometimes with the ground plug in place and sometimes without; they do not give any warning about using them ungrounded; just suggest you try them both ways.
In reference to PS Audio, their newer products I found contain a safety warning about the ground. Links [http://www.psaudio.com/wp-content/uploads/2011/11/HumbusterIII_-Manual.pdf][http://www.psaudio.com/wp-content/uploads/2011/11/P3001.pdf] [http://www.psaudio.com/wp-content/uploads/2011/11/Juice-Bar-II.pdf]
Their logic is a little fuzzy. They recommend to avoid disconnecting ground pin unless absolutely necessary and in next sentence they say removing this pin is dangerous? Maybe it is only 80% dangerous or perhaps it is dangerous on even Tuesdays and safe other times?
"Do not remove or bypass the ground pin on the end of the AC cord unless absolutely necessary to reduce hum from ground loops of connected equipment. This may cause RFI (radio frequency interference) to be induced into your playback setup. Removing or bypassing the ground pin on any electrical component is potentially dangerous and should be avoided for safety reasons."
"To prevent electric shock, use a 3 prong, grounded type power cable"
how can you possibly call yourself an audiophile if you aren't willing to die in search of better sound? motorcycling, scuba diving, skydiving, airplanes, etc. what are we men or mice?
It makes me curious about how much some of these companies know about power grid, cords, and other products they make. Any electrical engineer knows about the risk.
Maybe this was brought to their attention, and they put the risk, warning part in the manual to help keep them from getting into trouble if they go into litigation. They can say the customer didn't take the warning serious.
That pin removal was, or still is a selling feature for them.
Those ground adapters are banned in Nova Scotia Canada. Also, a college professor was electrocuted using one. So that shows it can happen. That's in the Wiki link. Link [http://www.gov.ns.ca/lae/electricalsafety/esbadapterplugs.asp]Wiki link [http://en.wikipedia.org/wiki/Cheater_plug]
You must have a verified phone number and physical address in order to post in the Audiogon Forums. Please return to Audiogon.com and complete this step. If you have any questions please contact Support.
