Assuming that your preamp has a grounding plug on it; yes, it will be grounded through the PS. I suppose many of the posters that scream about cheater plugs, didn't live through the era of non-polarized/ungrounded AC plugs(EVERYTHING pre-late 80's). After three decades(70's - 90's) of being in the electronics biz; I can't recall an instance of anyone being fried by their equipment. I suppose if they had grabbed a ground, and their phase was reversed; it may have gotten interesting. If the idea of an extra, low grade connection(the cheater plug) in your AC line bothers you: find the chassis ground lead, coming off the back of the IEC jack(inside the amp) and disconnect it. If your upgraded power cord uses the ground as an EMI/RFI shield, it'll still work. Unless your outlet is connected with the phase reversed; I THINK you'll make it!. BTW: You don't have any power cords, interconnects, etc. running close together/parallel, do you?
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Life is full of things one can be anal about. If the risk associated with using cheater plugs in an otherwise properly grounded system is your thing, so be it. I think I'd rather spend some time worrying about where to go when there is a thunderstorm approaching when I'm outdoors in rattlesnake country. At least I really do spend time in rattlesnake country................:-) People do get hit by lightning and bitten by snakes. Never heard of anyone getting electrocuted by the appropriate use of a cheater plug.
If you use a cheater plug, or disconnect the ground in the preamp, it will not be considered grounded. There is always a possibility of some kind of failure happening. With a preamp, the power switch alone is a risk. Lose connection somewhere in it too.
With the power switch off and on cycles, the plastic housing to the power switch itself can fail. Also, if the plastic housing fails, it can let the 120 volt energized contact touch the preamp housing. That of course can let the 120 volts energize the whole preamp cabinet. The 120 volt wire feeding the switch could break off, and contact the cabinet, energizing it.
That switch failure alone, happens often in all kinds of electrical products, besides home audio. When it happens nowadays, it usually trips the breaker, due to the ground.
I think grounded outlets became part of the electrical code
in 1951. This was done to save our lives. Yes I know, it can help make headaches with ground loop hum problems.
These cheater plugs are now banned in parts of Canada.
People still die from electrocution as seen here
Wikipedia has an article about them here.
Here is a news article about children swimming getting electrocuted (I had to shut off my ad block to read it). If it had the proper ground, they'd probably still be alive.
So yes, there is a risk.
Al (Rodman), what he's saying is that he is using a cheater plug to defeat the connection of the safety ground pin on the preamp's power plug to the safety ground pin of the PS Audio unit's outlet. Therefore the preamp's chassis has no connection to safety ground, other than perhaps (depending on the internal grounding configuration of other components in the system) via the return conductors of interconnect cables going to other components, and from there via the safety ground connections of those other components.
If a fault were to develop in the preamp that shorted the AC line voltage to the preamp's chassis, there are various scenarios in which that could result in both a shock hazard and a fire hazard. How great are those risks? Very, very small. But it cannot be said that they are zero. Grimace, as I said in your thread on the original problem, it's your call.
BTW, a suitably chosen Jensen audio isolation transformer (one of those shown towards the bottom of the page), as suggested in the Jensen paper I linked to in my post of 3-30-12 in the other thread, would most likely make the whole issue moot.
Yes- There IS a risk(indubitably); IF you happen to be grounded, when in contact with the hot side of a 120V AC circuit(or two hots of 240V single phase/any two hots of 3 phase). You HAVE to be the completion of a circuit, for current to flow. Grab the hot wire of a 120V AC line, and nothing will happen(unless some part of your body is in contact with neutral, or earth ground). The children, in that article, were electrocuted when they touched the energized metal ladder of the boat. Being in the water, grounded them(tragic). Ungrounded NEMA 1-15 sockets have been prohibited in new construction in the United States and Canada since 1962. Grounded cords & polarized plugs have only been common on electronic equipment, since the late 80's.
Yes Rodman. In 1951, the laundry outlet was required to be grounded. Then in 1962, all outlets were required to be grounded as you stated. That shows the grounding requirement must have shown an improvement, towards people dying from electrocution, at a slower rate. This grounding idea turned out to be good.
This link I posted above shows improvement over the years. New construction, remodeling, and electrical upgrades over the years seems to be reflected as the death rate was dropping. And they seem to keep trying to improve the requirements, since it sure seems to be working.
Years back, I've had a couple of years of tech level electronics to know how a person could get electrocuted. I'd like everyone to know how it works, so they could be safer doing anything that involves risk around lethal voltages. But, we know that's not practical for a lot.
All of those people that did lose their life at home while trying to enjoy something powered by electric is sad.
Everyone who did lose their life by electrocution in their home, sure met the criteria for it to happen. You don't need
to be in water.
If someone such as the OP of this thread, or a lot of others reading this, may not know how easy it can happen, is one of the reasons I don't recommend for them to bypass these proven grounding safety features.
One dangerous thing I can see happening if the OP bypassed the ground on his preamp, and something failed causing it be energized to 120 volts, is easily pictured in his system link. A lot of people, including the OP, may lean his one arm on top of the cabinet, against the grounded amp, and change the volume with his other hand touching that energized preamp. Complete circuit, and recipe for potential death.
That would fully meet the criteria for electrocution, similar to what you describe. Simple. Actually so simple, it's scary. And something like this can be easily overlooked. Even more so, by someone that doesn't have any electronic background, or training. So I just can not recommend bypassing the safety ground with a cheater plug.
Statistics... What a person wants to know is: What are my chances to be fried doing this?
Well it is pretty near the "what are my chances of being hit by a bus crashing into my home?" level.
Or what are my chances of being killed by a airliner crashing into my home?
Small really small.
So if you love to worry about stuff ,no matter how slight the risk. don't do it.
If you are slightly risk taking.. (say you actually drive a car..BTW that is way more risk.) then yeah do it.
((I have stuck my fingers into plenty of live wall 120V A/C duplex, and even changed them out.. And have gotten a buzz now and then.. It is not a big deal.. Well at least until one is solidly grounded!))
When I was an early teen; someone told me a metal cutting carbon arc could be created, using a pencil and 120V cheater wire. I tried it with a power cord, alligator clips, #2 pencil and a crosscut file. I was sitting on concrete block, with the file resting on another block. Neutral of the cord on the file, I proceeded to try to strike an arc. Nothing was happening, so- I picked up the file with my left hand, forgetting that I had the hot alligator clip resting on the top of my right hand(brain fart). The shock contracted and paralyzed all the muscles of my upper body. I instinctively jumped up and back, interrupting the circuit. Muscles that I didn't know I had, ached for a couple days, BUT- I'm not dead. That was over five decades ago, and I've never been the completion of a circuit since(working with electricity, almost daily, for the past 40 years). I remember it as a lesson in Situational Awareness.
I remember a story from Florida. A guy was in construction and carrying rebar up into a to-be high rise. Well he rotated into a 35,000Volt powerline. And was standing on a steel beam.
ALl that was left (that anyone could recognize) was his shoes melted into the beam.
This was one in one hundred million. Driving a car one can have similar results in one in sixty seven (lifetime, not per driving event). Easy.
So WHY DO YOU STILL DRIVE A CAR?
It really IS all about percentages...
Some say 'why take any risk" I say why worry.
True, do not be flippant about getting shocked, but then why make it into some bigger deal than it really is?
After having followed the expert comments on these threads, but without wading much further into the murky swamp of perceived risks and high-consequence/low-probability events (where I misspent way too much of my life), just an added thought or two:
Even in the presence of a rattlesnake, risk of being struck is very, very small. That said, if I knew that one was in my back yard, I probably wouldn't let neighbors or friends back there.
When I had a recent insurance claim on some of my audio equipment, the adjuster asked detailed questions concerning circuitry and connections. Not sure I would have wanted to try and explain how low-risk a cheater plug actually was.
If you've got a $15K system, family and friends in one's home, and ANY identified risk that's easily solved, why not: a) as advised, just spring for a couple of hundred extra bucks that will make the issue go away and might even improve your SQ; and b) then JUST FORGGEDDABOUTIT?
Elizabeth, Plane crashing or bus driving into your home does not depend on you and is therefore not worth discussing. Driving without seat-belts or good brakes is dangerous no matter how small chance of accident is. Similarly, leaving one metal cabinet (that was designed to be grounded) floating while next one is grounded is dangerous. Being irresponsible with proper grounding is not very smart, IMHO, but recommending it to others is much worse.
Something not mentioned is the sonic issues related to lifting a ground.
The problem is a ground loop, you lift the ground and no more hum. This is caused by the fact that some part of the signal chain (amp, preamp) is improperly wired.
For example if the chassis and circuit ground are the same thing, that unit will be prone to ground loop issues. Now to pass UL and CE (in fact any electrical code worldwide) the chassis has to be grounded. The issue is how to deal with the circuit ground if the chassis is grounded, and not have a ground loop.
The solution is simple but you would be utterly amazed at how many companies have not sorted this out! All that is needed is the circuit ground 'float' within the chassis, with all ground points like RCA connectors and the like isolated from the chassis. Then a moderate resistance is used between the chassis and circuit ground. This floats the circuit ground at chassis potential (electrical ground).
The added benefit is that now the chassis shields the circuit without injecting noise, something that results in better sound due to 'blacker backgrounds'.
So, IMO/IME its worth it to get equipment with bugs like this fixed! If done, you never worry about grounds again, and you don't have to mess with exotic (kooky) grounding schemes like a rod in the garden or some messed up stuff that is a recipe for trouble.
I know that may draw some criticism but honestly, get the equipment fixed and you will find out what I am talking about.
I would think that some return to ground is necessary otherwise system noise would travel from box to box. For instance noise induced in the shield has to find return to ground and it is far better to find direct path instead of currents traveling on ground wire of IC (causing voltage drops that appear as signal) to another box that is "closer" to ground even if everything is floating. Floating might also be a disaster in case of static discharge to connector ground since current will go thru all available paths (including signal path electronics) to find return, instead of quick return to local ground. I would use high voltage capacitor about 0.01uF/1kV possibly with 100k-1M resistor in parallel between signal and chassis ground possibly close to input connectors. Hard wired connection (like in IBM PC) is good when we have only one box but otherwise makes ground loops or cause large current between boxes plugged into different outlets when connected together.
I strongly agree with Atmasphere and some others. Fix the problem, don't cover it up and cross your fingers hoping for the best. Find the cause of the ground loop (it is fairly simple but tedious to do this), and either fix or replace the faulty piece of equipment. Do not use a cheater plug. This is lazy and seriously stupid. All the more reason to audition equipment in your home/system before you purchase it. If a ground loop occurs during auditioning, then find the culprit and remove it or fix it.
Also, anyone that recommends to lift the ground, use a cheater plug, not use seat belts and other dangerous things, are not your friends and are not looking out for your best interest.
Another "non cheater plug" solution for a difficult to isolate ground loop might be the Ebtech Hum X device (available from Amazon and elsewhere). I've been using a "cheater" with my C-J CT5 for 3 years, and just ordered the Hum X as a safer alternative. I don't believe the 6 amp max capacity of the Hum X will be an issue with the preamp current draw.
Anybody else using one of these?
Hi Minorl, Great advise. You sound like a very knowlegable person so perhaps you could answer a question I have.
I have an amp which is grounded properly driven by a pre-amp which is grounded properly. When I plug in a CDP it creates a ground loop and I get a hum thru the speakers. When I put a cheater plug on the end of the CDP power cord the hum goes away.
What risk to I incur in operating the system with this cheater plug in place? Why is that so? So I better understand, please create a situation where the risk you describe will be encountered. Please take it beyond electrical theory. If you can back it up by referring to an actual occurance that would be better yet.
In anticipation of the thoughtful reply I will receive, thanks. Perhaps I'm not lazy or seriously stupid, just a little bit ignorant. :-)
Newbee, if you use your CDP normally, probably not much will come of it. But if it gets dropped or abused in such a way that the power switch or AC power is able to contact the chassis, then you may have a problem. If the chassis is ground, a fuse will blow and all is well. If not, it may be possible to start a fire or create a shock hazard in the system.
Newbee; I agree with Atmasphere on this. If you unplug and disconnect every piece of equipment and then plug in the Amp to the speakers and turn it on and no noise. then plug in the pre-amp to the amp and no noise. Then plug in the CD player and there is noise. First thing I would suspect is a faulty ground scheme in the CD player. But before I replace it I would try other interconnect cables. the ones you are using from the CD player to the pre-amp may not be shielded properly or the shield may be tied to the signal ground. If you still have noise, then just for fun, plug in a different CD player or DVD player to the same input on the pre-amp. Noise? No? then your CD player has issues. Yes? Then it may actually be the pre-amp's internal ground scheme. But, I believe that it will be the CD player or the interconnect cables. If you try all that, then try this. Plug all you low level devices, Pre-amp, CD players, TT, etc. into the same conditioner device. Then plug your amp into the wall outlet. typically with all the low level devices connected together and the amp plugged into its own wall outlet (hopefully a dedicated line to the circuit breaker panel), not only will your noise floor drop significantly, but ground loops disappear.
09-11-12: NewbeeNot necessarily.
A good design will often have circuit ground and chassis connected together through a low value resistor (to minimize ground loop susceptibility, compared to having them connected directly together). That creates an excellent chance that the resistance will reduce the amount of fault current (that would flow from the CDP's "hot" chassis through the return conductor of the interconnect through the resistor to the preamp's AC safety ground) to a level that is too low to cause the breaker to trip. The result would be that the resistor and/or the interconnect and/or anything close to them might go up in flames. The resistor would most likely burn out, in any event. Then when the user comes over to investigate, the hot chassis would still be hot.
Sometimes high current diodes are paralleled with the resistor (as is a capacitor, for RF filtering purposes), to prevent those possibilities. But I wouldnt count on the diodes being present.
Also, if the user is connecting the CDP or other component having a hot chassis into the system while it is plugged into the AC, and with one hand he touches either the hot chassis or the ground sleeve of an RCA connector on an interconnect that is connected to the CDP and is about to be connected to the preamp, while touching the chassis of the preamp (or anything else that is grounded) with the other hand, 120 volts would be placed across his chest and arms.
Unlikely? Yes. Inconceivable? No.
If your chassis is NOT grounded to the wall outlet ground it will be floating above ground. With a VOM set to continuity, touch the chassis to the wall oulet "ground" and it should measure continuity showing it is indeed grounded. Removing a chassis ground might break a ground loop and sound good but it is deadly if you touch the unit's chassis, and any conductor to ground. If there is a fault in the system, the system is looking for a ground through YOU someday, and to earth. THAT is WHY the chassis has to be properly grounded at all times.
I would heavily advise to not let your chassis float ungrounded, and fix the ground loop.
Removing a chassis ground might break a ground loop and sound good but it is deadly if you touch the unit's chassis, and any conductor to ground.
Amend to 'could be deadly'. Its that 'could' that is why there are things like UL and CE directives.
In the old days the RCA ground was the same thing as chassis ground in a lot of cases. IMO that is a bad move, and the better manufacturers even in the old days avoided the practice.
The funny thing is that proper grounding also results in better sound. You would think more manufacturers would want to be on board with this....