To buy grounded or not to buy grounded. That is the question.
I recently happened on to a highly recommended web site and looked at power cord options. There were two basic options: grounded or non-grounded. Below is the copied info from the non-grounded cord page.
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"Description Non-grounded cord (Ungrounded, the ground wire is removed from cord, with G-plug still intaked)
WHY?
Based upon measurements and listening tests; I have recommended to people, to ground only one piece of their interconnected equipment. The interconnects will provide static dissipation through the secondary ground connection & nuetral. They often look at me in extreme terror.😱
Wikipedia agrees…
Wiki; A ground loop is the result of careless or inappropriate design or interconnection of electrical equipment that results in there being multiple paths to ground where this is not required, so a complete loop is formed. In the simplest case, two items of equipment, A and B, are each connected to a wall socket by a 3 conductor cable, containing a protective ground conductor. This becomes a problem when a interconnect cable is connected between A and B, to pass data or audio signals. The shield of the data cable is typically connected to the grounded equipment chassis of both A and B. There is now a ground loop.
How can you benefit from this? Purchase the Grounded cord to hook to your preamp or integrated receiver…All other power cords in the system, such as source equipment, dacs, amplifiers, subwoofers,etc. should all use the non-grounded cord. This will direct ground your system, removing hum and reduce harmonic distortion from your system. We’ve seen multi thousand dollar power conditioners that do not fix or address this issue. The issues of ground loops are often greater then the dirtiness of the actual AC power!
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Hot: The black wire is the hot wire, which provides a 120 VAC current source.
Neutral: The white wire is called the neutral wire. It provides the return path for the current provided by the hot wire. The neutral wire is connected to an EARTH GROUND!!!
Ground: The bare wire is called the ground wire. Like the neutral wire, the ground wire is also connected to an earth ground. However, the neutral and ground wires serve two distinct purposes.
The neutral wire forms a part of the live circuit along with the hot wire. In contrast, the ground wire is connected to any metal parts in an appliance such as a microwave oven or coffee pot. This is a safety feature, in case the hot or neutral wires somehow come in contact with metal parts. Connecting the metal parts to earth ground eliminates the shock hazard in the event of a short circuit. (KEY WORD IS SHORT CIRCUIT, Meaning your electronics are broken!)"
A ground loop is the result of careless or inappropriate design or interconnection of electrical equipment that results in there being multiple paths to ground where this is not required, so a complete loop is formed.
That is not quite exactly correct. In a typical audio system, multiple paths to ground are often required for safety, with multiple components each enjoying the protection of a safety ground connection. That is only a problem if the grounds are at different electric potentials. Provided the electric potential of each is the same, the "ground loop" will cause no audible problems, such as hum.
Purchase the Grounded cord to hook to your preamp or integrated receiver…All other power cords in the system, such as source equipment, dacs, amplifiers, subwoofers,etc. should all use the non-grounded cord.
That is potentially hazardous, and could result in a component lacking a safety ground to have potentially hazardous current flowing through an interconnect, for which it isn’t designed. It is never wise to defeat a safety ground for anything other than testing purposes.
The solution to a noisy ground loop is not to eliminate a safety ground - that’s throwing the baby out with the bathwater. The proper remedy is to work to get all grounds at the same electric potential.
Cleeds is correct. When equipment manufacturers put a power cord on with a third prong, they really want you to ground their unit. Not doing so creates a safety hazard, sometime a lethal one. Yes, if something internal fails or breaks you can have 120VAC line on the chassis, but that is not the issue of what I saying. Internal equipment can "leak" line current through parasitic capacitance, mutual coupling, etc. which will put some AC voltage on the chassis. Touching an ungrounded chassis with a real ground will run that current right through you. When you work around electronics and electricity long enough, you will get zapped sooner or later. Early in my EE career I discovered just how conductive concrete is. I got seriously zapped just from this, not plugging a power supply ground into a grounded outlet and standing on concrete. The problem with that third prong is sometimes they get plugged into a different outlet than the rest of the equipment and you get a ton of hum. There are a number of reasons for this but do what Cleeds stated - get all the grounds at the same potential. The easiest way to do this is to power everything from one outlet box and use that ground for everything.
If a ground loop is a problem, where do you hear the hum? In the device itself? Through the speakers? Both?
I have had three sources of hum.
1) Cheap TT motor. Needs to go in trash. 2) Second hand Denon tuner. Mechanical sounding hum in the unit.Not heard through speakers. Goes away with book on top. Rarely use it. 3) One instance of hum through speakers when linking Apple TV with DAC via Toslink. Never duplicated. Don’t use this much anyway.
Otherwise, even at max volume my speakers are silent when nothing is being played.
Does this mean that there are no serious grounding or ground loop issues? My house is old but has both water pipe and copper rod grounding.
"Description Non-grounded cord (Ungrounded, the ground wire is removed from cord, with G-plug still intaked)
Power cord is not Listed by any 3rd party testing laboratory.
in case the hot or neutral wires somehow come in contact with metal parts. Connecting the metal parts to earth ground eliminates the shock hazard in the event of a short circuit.
It also provides a low resistive path for ground fault current to return to the source in the event of a hot Line to chassis fault. A hot to chassis fault will cause an overload in the equipment AC line fuse causing the fuse blow breaking the fault circuit. (Fault on load side of fuse) If the fault is ahead of the fuse the only protection then is the branch circuit breaker that protects the branch circuit wiring. No way, jmho, the small wire of an IC will handle possibly over a 100 amps of inrush fault current.
Based upon measurements and listening tests; I have recommended to people, to ground only one piece of their interconnected equipment. The interconnects will provide static dissipation through the secondary ground connection & nuetral. They often look at me in extreme terror.😱
Sounds good but has anyone run any tests or experienced an IC carry, handle, the ground fault current in the event of a hot to chassis ground fault? You might want to look at the wiring schematic diagram of your audio equipment. Good chance you will find the signal ground is not connected directly to the chassis.
Even if the IC can handle a high current inrush ground fault will the signal ground circuitry of say a preamp be able to handle it long enough for the AC line fuse in a power amp to blow open? Jim
Based upon measurements and listening tests; I have recommended to people, to ground only one piece of their interconnected equipment. The interconnects will provide static dissipation through the secondary ground connection & nuetral. They often look at me in extreme terror.😱
A little knowledge is a dangerous thing, and in this case potentially lethal. Do not follow this advice.
Based upon long term driving comfort, and gas mileage I’ve decided to remove the air bags and seat belts and spare tire from my car. I’ve never had a problem, and I save money thanks to the car being lighter.Plus, my daughter really likes riding on my lap instead of her baby seat.
I would bet those ungrounded cords are not U L approved. Should one of them catch fire, would the homeowners insurance cover it? I am willing to bet they wouldn’t.
I would bet those ungrounded cords are not U L approved
They're probably UL listed. There's nothing inherently unsafe with a two-prong power cord. It's using it on a device that is designed for a cord with a safety ground that's hazardous.
Should one of them catch fire, would the homeowners insurance cover it?
It would almost certainly be a covered loss. Carelessness isn't a typical exclusion.
I would bet those ungrounded cords are not U L approved
They’re probably UL listed. There’s nothing inherently unsafe with a two-prong power cord. It’s using it on a device that is designed for a cord with a safety ground that’s hazardous.
Should one of them catch fire, would the homeowners insurance cover it?
It would almost certainly be a covered loss. Carelessness isn’t a typical exclusion.
@ cleeds From the OP’s posted message
"Description Non-grounded cord (Ungrounded, the ground wire is removed from cord, with G-plug still intaked)
2 wire cord with 3 wire Plug and 3 wire IEC female connector. The female IEC connector would have to be a 3 wire. A 2 wire female IEC connector would not connect to a 3 wire IEC male connector on a piece of equipment designed to be grounded. No hole in the 2 wire connector for the equipment ground blade. Not only is the power cord not listed it could leave the person building and selling them liable in a court of law in the event of a person being electrocuted.
2 wire cord with 3 wire Plug and 3 wire IEC female connector. The female IEC connector would have to be a 3 wire. A 2 wire female IEC connector would not connect to a 3 wire IEC male connector on a piece of equipment designed to be grounded. No hole in the 2 wire connector for the equipment ground blade.
You’re correct, of course - I should have reviewed the OP. There’s no way this could be a UL approved cable.
OK, I'll chime in, although it will most likely be lengthy...
Let's establish a few electrical facts first; If a piece of equipment comes with a two-prong (hot and neutral) plug then the chases is bonded and passes any short to the neutral.
If it comes with with a three prong (hot, neutral and ground) then it most likely has an isolated chassis, meaning if there is a short to chasis the ground takes the load. If it has been replaced with a two prong cord then it is just waiting for anything to give the short a ground (meaning YOU!).
Let's try to clear up another misunderstanding; the wrapping of a foil shield or 'drain' around a wired connection between two pieces of equipment is not for grounding but to stop RF ingress. Back in the 'day' when I was doing instrumentation this was only terminated on one end to drain off any interference it had stopped and NOT bonded between two pieces of equipment.
Now for the jobs of ground and neutral. A neutral is to provide a return path for a 120 or 208 VAC circuit. A ground is to provide over-current protection. End of story...so far.
In a typical U.S. residential distribution panel you have two opposite phase 120 VAC circuits and one neutral coming from the utility. In the panel every other circuit is on the opposite phase and each circuit has its own neutral (actually if two circuits in a particular run are opposite phase they can share a neutral but nevermind...) and each circuit has a ground. The neutral return to the panel to the neutral bus and the grounds go to a ground bus that has a number 6 wire going directly outside to a groundrod and then they are.......BONDED! So.....what gives??
If you were to go and look at the utility poles the come to you house (provided they are up to IESC codes) you will notice a ground wire coming down each pole to the ground and that each utility on that pole (phone, cable, fiber) each have a 'bond' to that wire that originates from the neutral wire which is typically the bottom wire in town and the top wire in rural areas. This is the ground plane. The ground rod at your home adds to this as a stop-gap from surges TO YOUR HOME. It is NOT where most of the ground and neutral goes from your home. Why? Because a circuit looks for the shortest route to a ground, and that "ground" mean the least amount of resistance. Your paltry groun-rod most likely has a high resistance value so the bond between ground and neutral is to use the utility's ground plane (over the neutral) to absorb over-volatages cause by shorts and shorts to ground. In other words, if a short were to rely solely on your ground-rod with a high resistance, it would be like a long line at the grocery store, and the utility ground is when 10 other checkers open up their lanes then all the customers run to the shortest line.
So now that we've established what the ground and neutral are for, what causes a ground loop? In my experience of dealing with humbars on TV channels it was because there wasn't ENOUGH ground between the pieces of equipment so the answer was to always make sure everything was bonded together. In most cases this alleviated the issue.
Never disable or not Connect a safety ground from a device that has a grounded connection. One time I thought I plugged an device into a grounded wall outlet but ground was internally never connected. When I touched a outer part of an RCA connection I got seriously hit by a current. I became ground.
I prefer to to stay above ground above “Beter sound” or solving a problem like this. In my case it was an accident but it had te potential to be a lethal one.
Let’s establish a few electrical facts first; If a piece of equipment comes with a two-prong (hot and neutral) plug then the chases is bonded and passes any short to the neutral.
The chassis is bonded to what? Not the neutral conductor..... The neutral is a current carrying conductor and is never bonded, connected, to the chassis. Been that way for at least the last 58 to 60 years.
Class II power wiring
Class II Class II symbol
A Class II or double insulated electrical appliance is one which has been designed in such a way that it does not require a safety connection to electrical earth (ground).
The basic requirement is that no single failure can result in dangerous voltage becoming exposed so that it might cause an electric shock and that this is achieved without relying on an earthed metal casing. This is usually achieved at least in part by having at least two layers of insulating material between live parts and the user, or by using reinforced insulation.
I never said I had a problem. On another thread I was reading, three people recommended Audio Envy interconnect cables. I found their website and was looking at the interconnects, and then thought I would also check out the power cords as well. I just noticed the ungrounded power cord product with accompanying statement and though I'd run that past everyone. I'm not looking for any help - I was just interested in a little discussion of the recommendation of ungrounded power cords in audio systems. The address of the site that I wandered on to is: audioenvy.com
The term I haven’t seen in this thread yet is "Double Insulated". In any power tool, you might see a typical three-prong plug, or only a two-prong plug. In the latter, the tool is often labeled as double-insulated, meaning that it has been designed and manufactured in such a way to have the electrical portion entirely isolated with safety in mind. Presumably, this is also what’s done with a piece of audio equipment that comes from the factory without a grounded plug. Cutting the ground prong off of a three-prong plug yourself is both ill-advised and dangerous.
jea48, sorry, just saw your last post, you beat me to it.
PS Audio made a power cord where you could unscrew the grounding pin.
Yes. PS Audio states the grounding pin should only be removed for testing purposes only. Basically covering their butt.
Audio-envy on the other hand clearly states they are manufacturing an electrically dangerous power cord with grounding type connectors, (especially the female IEC connector) so the user can use the non earthed equipment ground power cord on equipment that is designed, manufactured, and safety tested by a recognized testing laboratory to be earth grounded.
I wouldn’t even classify the Audio-envy power cord as a ground cheater. A 3 wire to 2 wire adapter is UL listed when used as intended.
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