if i understand correctly (and I'm guessing that I don't), only one component in a given system should be grounded.
so does that mean that all you guys with your GNP-level systems, plumbed with bazillion dollar power cords, are using a bucketful of home depot-style ground lifters? I'm having a hard time wrapping my head around that. Is there some source for solid-gold cryo'd ground lifters I have not found?
How is this problem addressed? My searching skills are failing this morning...there was a lot of chilean and argentinean wine involved last night. thanks.
Based on what you have been reading, you have two lines of thought and advice. 1). Audiophiles that really no nothing about electricity and grounding that advise doing the quick and dirty fix by lifting grounds and 2) people that understand electricity and the rules of house wiring, by telling you quite simply, to never lift grounds. find the problem equipment and fix or replace it. Balanced loads and yes, any electrician worth their salt will balance AC and other appliances on each side of the phases. it is not randomly attached. It is the ultimate wrong thing to do to advise anyone to compromise the electrical system and rules. If you are touching your equipment or sometimes another piece of equipment or metal in your home and a fault occurs, either in your home, piece of equipment or outside (lightning strike, etc.) that ground that you just lifted offers the safe path to ground for current, but you just lifted it. So, electricity will try to find the shortest path to ground. it could be through another piece of equipment with a ground, you if you are touching something at the time, or a family member. Find a licensed electrician and ask. This is not a good idea. I know, I'm not telling you what you want to hear, (maybe I am), but, shortcuts never are good. In equipment design and construction or otherwise. Do the hard work early and life is easier later on. no shortcuts.
Also, some equipment with three prong power cable actually have the ground lifted inside the chassis. I've owned several amps wired this way. 04-25-10: Albertporter
If the amps are UL and or CSA listed then that would imply the AC power wiring of the equipment is double insulated thus meeting UL/CSA standards.
I would rather see the manufacture of the equipment use a C-14 or C-20 plug on their equipment with the ground contact pin removed. That way the consumer/user would know if an equipment grounding conductor was needed for the equipment. Or better yet how about the manufacture be required to print on the back of the unit along with the AC power consumption and Hz if the unit is wired with doubled insulated AC power wiring.
IEC connectors are the only UL/CSA listed plug and socket that I know of that can be used for both 120Vac as well as 220Vac. Can't do that with any NEMA plugs or receptacles. The IEC plug is the only one I know that can be used in electrical equipment and float the equipment ground contact. You could not do that with any NEMA two wire with ground Plug.
So I guess the question to be asked, does my equipment that uses IEC connectors use the safety equipment ground? No equipment ground contact pin in the IEC plug, no.... If the ground contact is present on the IEC plug then the only 100% sure way to know is pull the top cover off the equipment and look inside.
Could use a meter and check for continuity from the equipment ground contact of the IEC plug to the chassis. If the meter shows short then yes the ground contact is connected to the chassis and the equipment ground is needed for safe operation.
If the meter reads infinity/open I would not bet the bank 100% on the reading. Can you say 100% both test probes were making good contact? Pop the hood and look inside.... Or you could contact the manufacture.
Remember,this means absolutely nothing if your receptacles are wired wrong. Don't laugh, it happens all the time. Tpreaves (Threads | Answers)
Or if your electrical is wired reversed inside the equipment. This happens too.
Also, some equipment with three prong power cable actually have the ground lifted inside the chassis. I've owned several amps wired this way.
Guess that falls into the category of XLR inputs that are jumped over to the RCA so customers can operate their system in balanced.
In that case it should be referred to as a convenience jack. I've owned several products like this, many people think because the plug is there the unit is properly wired to accommodate it.
The neutral blade on the plug will be slightly wider so as it will only plug into the receptacle in one direction. The plug is polarized. This is needed so the switch and fuse protection for the equipment is in series with the hot conductor.
Remember,this means absolutely nothing if your receptacles are wired wrong.Don't laugh,it happens all the time.
...how can I tell whether my equipment is a three wire cord and plug deal or the kind that's safe? 04-24-10: Auxetophone
Auxetophone,
In the case of a three wire cord and plug if the equipment ground is not lifted and the electrical continuity integrity of the branch circuit safety equipment grounding conductor is good all the way back to the electrical panel the equipment is for all practical purposes safe. (Three wire plug? 2 straight blades, hot and neutral, with a round ground pin. USA)
Here is a stickler though.... More and more equipment may use an IEC plug on their equipment with a 3 wire cord and plug. If the the IEC plug is inspected you may find there is only 2 blades, the hot and neutral. No equipment ground contact. In this case the equipment was built with double insulated AC power wiring. The equipment grounding conductor of the power cord is not used.
The reason for the standard IEC plug,(minus the ground pin), on the back of the equipment? The consumer can use 3 wire cord and plug after market power cords.
Equipment with fixed power cords if the equipment ground is used must have a 3 wire cord and plug. (Hot, neutral, and equipment grounding conductor.)
Equipment with a fixed power cord that uses double insulated AC power wiring will use a 2 wire cord and plug. The neutral blade on the plug will be slightly wider so as it will only plug into the receptacle in one direction. The plug is polarized. This is needed so the switch and fuse protection for the equipment is in series with the hot conductor. Also for the proper AC polarity orientation of the power transformer, that is if the manufacture checks every transformer before installation.... The big boys do... Every power transformer.
Actually, if something goes wrong with the equipment - like a B+ wire touching the chassis - you're better off sending that to ground and blowing a fuse, than letting it sit out there to electrocute your kids. 04-23-10: Auxetophone
Auxetophone, If B+ were to short across to the chassis the power supply would overload and hopefully blow a fuse, that is if the equipment has any power supply overcurrent protection. B- is usually connected to the chassis..... Again in this case the safety equipment ground would not make any difference connected or lifted.
The Link you provided is in regards to three wire cord and plug equipment connected to an AC grounded electrical system. I am familiar with the article. The article tells it like it is.....
"The only way to get a shock from the B+ is to actually put yourself in series between the B+ and B- ..... Lifting the safety ground would not change the likelihood one way or the other....."
Actually, if something goes wrong with the equipment - like a B+ wire touching the chassis - you're better off sending that to ground and blowing a fuse, than letting it sit out there to electrocute your kids.
I wouldn't call that a ground loop. If there was something like that, it would cause the ground to be noisy. 04-23-10: Atmasphere
Could it cause a ground loop hum?
Why would it be any different than ground current flow from a CATV system? In both cases current is flowing through the equipment ground. We know current will take any provided path back to the source. If the ground current flow is present what would prevent it also from flowing through the ics signal ground to other three wire cord and plug safety grounded equipment to get back to the source?
Jea48, I wouldn't call that a ground loop. If there was something like that, it would cause the ground to be noisy. While a ground loop is also a noisy ground, the difference is that the former is caused by a malfunction rather than a gain stage later in the signal chain.
04-23-10: Atmasphere Yes, it does not matter tube or transistor. The real issue would be if somehow there is leakage from a power transformer. 04-23-10: Atmasphere
Atmasphere, Speaking of transformer leakage.... Say there is a slight leakage in the primary winding of the power transformer to ground, small, not enough current flow to cause an internal equipment fuse to blow. Current flow to ground never the less. Could this small current flow cause a ground loop hum problem? (By leakage I mean other than capacitive leakage.) Jim
It's probably worth pointing out that the danger from lifting grounds is much higher with tube components. These typically have 300+ VDC - very deadly. 04-22-10: Auxetophone
The only way to get a shock from the B+ is to actually put yourself in series between the B+ and B- ..... Lifting the safety ground would not change the likelihood one way or the other.....
It's probably worth pointing out that the danger from lifting grounds is much higher with tube components. These typically have 300+ VDC - very deadly.
Also, this comment
"Having all of your high power equipment on one phase will overload the wiring, cause it to heat up (IxIxR) losses and cause the insulation to fail causing a major electrical fire"
seems a little out of touch in an audio context. It's unlikely that any audio circuit - no matter how powerful or loudly played - will draw as much current as a wall air conditioner. I don't know anyone who checks to make sure the air conditioner and refrigerator are on opposite phases. These two are a much bigger load than having your power amp and cd player on the same outlet.
I understand what you are saying. However, in terms of electrical design and safety and codes, you never, never, never lift grounds. If there is a problem, hum, ground loops, etc. isolate the faulty piece of equipment or cable and fix or replace it. Like I implied earlier, all you need is for it to happen once for you to realize what a bad mistake you made by lifting the ground and compromising the electrical safety. That is, if you are still alive to talk about it. It may not be you. It may be a child or guest. I have experienced ground loops and hum before. I took the time to isolate the faulty equipment and fix or replace it. I'm very much into great music and accurate, detailed reproduction of the signals, but not at the cost of safety. Life is short enough as it is. I don't mean to rain on anyone's parade but, cutting corners and shortcuts are not the proper way. One should never advocate compromising safety.
the human body is an impedance. resistance, inductance and capacitance. You have an impedance. If there is a system fault or a lightning strike, or some such, very high voltages can pass through the equipment through you to ground.
That is a lot different statement than the one I quoted of yours in my previous post...... Yes if any part/s of the body is placed between a difference of potential, current will flow through the contact points. If the voltage and current is high enough there will be electrical burns at the entry and exit points. And yes it can kill you deader than dead! In the case of a ground fault the current is non discriminating.... It will take any conductive path available to get back to the source. It likes the least resistive path but it will still take any available path.
We are not talking about audio equipment. We are taking about electricity, voltages, sometimes very high voltages, current and impedances. a blown transformer and you have very high voltage spikes, a shorted device or a failed tubed device and very high voltages hit you passing very high currents through your body. Since you are an impedance, small but there, you will draw very high currents.
You really need to go back and read my other responses to this thread.....
the human body is an impedance. resistance, inductance and capacitance. You have an impedance. If there is a system fault or a lightning strike, or some such, very high voltages can pass through the equipment through you to ground. Since you lifted the ground, you become the easiest path to ground. We are not talking about audio equipment. We are taking about electricity, voltages, sometimes very high voltages, current and impedances. a blown transformer and you have very high voltage spikes, a shorted device or a failed tubed device and very high voltages hit you passing very high currents through your body. Since you are an impedance, small but there, you will draw very high currents.
As an Electrical/Electronics Engineer, I am telling you that lifting the ground and you become a better ground than the house ground and electricity will take the easiest path to ground and that becomes you.
Say what? Please explain how the human body can be a ground for an AC grounded power system......
Also, the load in your home should be balanced on each phase. Having all of your high power equipment on one phase will overload the wiring, cause it to heat up (IxIxR) losses and cause the insulation to fail causing a major electrical fire.
We are talking about audio equipment here.... In most cases all the combined connected loads would only add up to around 8 to 10 continuous FLA at best... Most hair dyers pull more than that.
The following paper, by Bill Whitlock of Jensen Transformers, presents a good explanation of why equipment connected via unbalanced interfaces (i.e., rca cables) is inherently prone to the kinds of problems that have been mentioned, and presents some approaches to dealing with these problems that do not involve lifting safety grounds:
I again want to reiterrate that removing grounds is not only unsafe, it is irresponsible and the potential is not for electric shock, but for death. People are minimizing what could happen here. As an Electrical/Electronics Engineer, I am telling you that lifting the ground and you become a better ground than the house ground and electricity will take the easiest path to ground and that becomes you. There are many ways posted to find the faulty equipment. Please do so and fix the problem, do not lift grounds. Remember, "Accidents" happen when you do not expect them to. Lifting a ground in my opinion and getting severely shocked or causing a death is not an "Accident" you were asking for it by lifing the ground. Also, the load in your home should be balanced on each phase. Having all of your high power equipment on one phase will overload the wiring, cause it to heat up (IxIxR) losses and cause the insulation to fail causing a major electrical fire. Imagine having one outlet or several outlets in series back to the panel on one phase. You now have a 10, 12 or 16 gauge wire w/neutral caring all that current. Is that wire rated for the maximum amount of your equipment? If not, no electrician worth their salt would allow this. Having your equipmen balanced on each phase is the proper way and having several independent outlets run to each phase with their own neutrals is the proper way. Example would be if you have mono amps for your speakers. One proper way is to have separate outlets for each amp run back to the panel and another outlet run to the panel for the lower powered equipment (pre-amp, turn table, tuner, cd player, etc., which should be combined via a conditioner, or multiple outlet device.
I must assume from some that have posted here no one that lives in an older home that has only 2 wire receptacle outlets, (no equipment grounding conductor), has audio equipment that has three wire plugs.
My home was two prong plug when I moved in and never had a noise problem. Over the years as my AC was upgraded and the three prong plugs of audio gear were actually connected to ground, I began to have problems.
When I say problems, realize that having done photography for various audio manufacturers and reviewed equipment for PFO as well as my audio groups testing, I've had a heck of a lot of equipment connected here.
Ralph is right that grounds are done many different ways on various pieces of audio gear and sometimes all you need do is change preamp or amps and the problem pops up.
No one has mentioned electrical phase. Many stereo systems are connected to both phases (or sides of the supply transformer outside) with ground shared. Good way to get hum and very difficult to get rid of.
Again, equipment dependant. I'm sure some of you are connected this way and have zero problems.
Why any manufacture of audio equipment today would still be designing and building their audio equipment using the old out dated AC safety equipment type of grounding beats me.
Double insulated type AC power wiring in their equipment would not cost that much more to produce.
I must assume from some that have posted here no one that lives in an older home that has only 2 wire receptacle outlets, (no equipment grounding conductor), has audio equipment that has three wire plugs.
UL should require all manufactures to build their audio equipment with double insulated power wiring or the manufacture would not get the UL label.
The way it is done in pro-audio situations is to make sure the heart of the system (in a pro audio system: the mixer, in a home system: the preamp) is the only thing that is grounded. Otherwise there is a good likelihood of a ground loop between the amp and preamp.
The concern is that you could get into some serious shock hazard, which is why so many advocate not to do it. And it is true that if the equipment is properly designed, you won't have any serious ground loops to begin with.
The caveat is 'properly designed'. I've seen about 10 different ways of grounding used in various brands of equipment and some methods work a lot better than others.
Add to that the fact that buzz is a rather crude manifestation of a ground loop, IOW you can have a ground loop and no buzz, just a loss of detail and an increase in background noise. So the more adventurous audiophiles may take things like this into their own hands- Albert is a great example of that.
So if you are going to be lifting grounds, I agree with Albert. Just keep in mind that there is the potential of shock (no pun intended), but personally I have never seen this actually manifest (I've done this a lot in my own system) in over 30 years. All it takes is once though! So although it may help, its not recommended. So if you attempt something like this, just keep in mind you are at your own risk.
Absolutely never lift grounds. You are taking out of action the method used to protect you. If you have hum or noise, then you should investigate each unit individually until you isolate which piece of equipment is causing the ground loop or hum and fix it. Lifting the ground may mask the ground loop or hum problem, but you have now introduced a potential for serious injury or death. No joke! This is the same logic as taking a radio or hair dryer into the bath tub. Everything is fine until is slips out of your hand and falls into the water, then it is too late. You are asking for trouble lifting grounds. Find the problem and fix it. Lifting grounds does not fix the problem. There are many posts here that explain the method for isolating which component is causing the problem.
There is absolutely no excuse for any need to lift grounds. All properly designed equipment should be quiet without this VERY serious safety violation.
All the PS Audio power cords have a removable ground pin for this very reason. They seem to be well thought out plugs. 04-18-10: Mulveling
True,... but you will also notice they are not approved by UL or any other recognized testing agency.
On my system the solution is open the IEC Oyaide (equipment end) and lift the ground.
The reason to not do this at the wall is that would leave the ground as potential antenna into the equipment. This method leaves the wall plug ground pin in place which helps secure connection, especially for heavy AC cords. 04-17-10: Albertporter
Albert is not alone in his thinking about the lifting of the equipment grounding conductor at the source end of the PC acting as an antenna. There are a few EE on AA that say the same thing. Remember the other end of the power cord's equipment grounding conductor is still connected to the case, chassis, of the equipment. One other point that comes into play is the small induced voltage from the hot conductor of the PC that crosses over into the lifted equipment grounding conductor. With the induced voltage EMI/RFI noise can travels up the PC equipment ground conductor to the chassis and on into the signal ground of the piece of equipment as well through ICs to other pieces of equipment.
In previous incarnations of my system, it worked well to have just the preamp with a 3-prong plug, and the other components (phono stage, power amp) on a 2-prong plug. Putting a 3-pong plug on my old power amp yielded a loud BUZZZ. However, my new monoblock amps (maybe due to their balanced input stage) and phono stage are both doing just fine with 3-prong plugs as well. 04-18-10: Mulveling
I read this a lot here on Agon and AA where the preamp is used as the connection for the safety equipment ground for all other three wire equipment connected together by their ICs. Star grounding.....
I have yet to read any post where a ground fault condition , say from a power amp, successfully passed through the ICs to the preamp signal ground > to the chassis > on out the PC > through the equipment grounding conductor of the branch circuit to the electrical panel causing enough current flow to cause the branch circuit breaker to trip open.... I would appreciate any links to the contrary.....
Jea48, Could you explain "JMHO if you are going to lift the ground do it on all the three wire cord and plug audio equipment."? I didn't quite get it. Thanks 04-18-10: Maril555
First I do not advocate lifting the safety ground. But if you must, JMHO, it would be safer to lift the ground on all equipment that uses the safety ground. To receive an electrical shock there has to be a difference of potential, voltage, that a person's body comes into contact with. I personally would not rely on the ICs from a preamp to a power amp for a suitable ground fault path from the amp to the preamp. Instantaneous ground fault current flow can be well over 100 amps. Will the #20 ga wire withstand that amount of current flow long enough for the 15 or 20 amp branch circuit breaker to trip open. Better yet how is the output of the preamp jacks signal ground connected to the chassis? Could the path pass a high ground fault current flow?
Basically what I am saying if you have to lift the safety ground do it on all the equipment. Remove any chance of a difference of potential to a grounded object within arms length or from any part of the body to any electrically grounded object.
Food for thought. A bird perches on a high voltage wire and does not receive an electrical shock. A squirrel jumps onto a high voltage wire and runs down the wire without a care in the world. His fate is in his method of dismount.
Jea48, Could you explain "JMHO if you are going to lift the ground do it on all the three wire cord and plug audio equipment."? I didn't quite get it. Thanks
All the PS Audio power cords have a removable ground pin for this very reason. They seem to be well thought out plugs.
In previous incarnations of my system, it worked well to have just the preamp with a 3-prong plug, and the other components (phono stage, power amp) on a 2-prong plug. Putting a 3-pong plug on my old power amp yielded a loud BUZZZ. However, my new monoblock amps (maybe due to their balanced input stage) and phono stage are both doing just fine with 3-prong plugs as well.
I use a piece of teflon plumbing tape to cover the ground of the IEC male inlet on the back of each component. Simple, effective, and no additional connections are needed. You can also use a piece of electrical tape.
Lifting the ground may lower the noise floor in some components. I also use a specialized external grounding unit that is a noise sink.
JMHO if you are going to lift the ground do it on all the three wire cord and plug audio equipment.
Make damn sure if multiple dedicated branch circuits are used the circuits are all fed from the same Line, leg, of the electrical panel. Use a volt meter to confirm.....
The object is to not have anything within arms length that is grounded. If a ground fault current path does not exist there cannot be a difference of potential for an electrical shock to happen.
Now of course if the floor is bare concrete or any other conductive surface lifting the ground would not be a good idea.
No definitive advice on what components are best grounded and which best ungrounded. Over the years that answer has changed, dependent on individual components and even RCA versus XLR cable terminations (maddening).
Ground is one of the most misunderstood and difficult issues in high end systems. Get it right and everything sounds better and you obtain that nice black background that everyone wants. Get it wrong and you chase hum and buzz around via various sources.
I've had my share of this in my own system even though I run star grounds and dedicated lines for every piece in my rig.
As for the cheap ground lifters, I find them invaluable for testing, no sense in permanently lifting the ground on a AC plug just to see if that helps. The lifter lets you know where to work and then you can make it permanent.
it's like being visited upon by the gods when you weigh in, Albert. Seriously, thank you for taking the time. Very much appreciated.
Thank you but that does not apply to me. I do post a lot but as with most things in life, you get back pretty much what you put in. I can't count the number of time another Audiogon member has posted a comment and I cannot add a word, because it was so perfect.
On my system the solution is open the IEC Oyaide (equipment end) and lift the ground.
The reason to not do this at the wall is that would leave the ground as potential antenna into the equipment. This method leaves the wall plug ground pin in place which helps secure connection, especially for heavy AC cords.
All that being said, care must be taken when lifting the ground on any piece of equipment as the potential for shock is greatly increased.
so does that mean that all you guys with your GNP-level systems, plumbed with bazillion dollar power cords, are using a bucketful of home depot-style ground lifters
I've often wondered the same thing,seeing how often they are recommended.
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