So, I just noticed that if I plug ONLY my receiver in the outlet and unplug the computer the hmmm goes away, but as soons as I plug my computer the noise comes back

I'm trying to figure out a safe way to connect my receiver to my computer through ground

 

You can also remove all devices from the sockets and put them back in one after the other, touch the plug after each device to see if current flows, then you should find out which device is defective or causing the current surge.

 

Audio playback on the PC: The cause of the annoying hum loop

Whether listening to music MP3s, watching movies, or playing their favorite game, many PC users prefer crisp bass from the audio output via the HiFi stereo system to the rudimentary sound image via the PC "roaring cubes". In many cases, however, this listening pleasure is marred by a clearly audible hum.

In these cases, the source of the disturbance is a ground loop ("hum loop"), because all modern electrical devices and current-carrying power cables produce alternating magnetic fields with a frequency of 50 Hz.

In most cases, this hum is caused by a double grounding through the audio signal cable between the PC and the HiFi system on the one hand, and the grounding contact conductor and the antenna cable in the system on the other. There are several ways to remedy this problem.

Your 7 professional measures against disturbing humming during sound reproduction from the PC

1. With a little luck it is enough to connect either the PC or the HiFi components to another grounding contact socket or to operate all involved consumers at a grounding contact socket.

2. A simple trick is to reverse the grounding plug of one of the components involved in the ground loop, usually PC and amplifier/receiver. This reverses phase and neutral, which helps amazingly well in some, few cases.

3. Another solution: disconnect a part of the hum loop in the meantime by unplugging the antenna cable of the HiFi receiver or a TV or radio tuner card located in the PC.

4. It can also be helpful to connect the housings of the hi-fi amplifier and PC with an additional cable. Such a ground cable can be easily attached to the rear housing screws.

5. An additional ground cable between the housing of the audio amplifier and the protective earth contact of the grounding contact socket probably also solves the problem. Such a cable is particularly easy and universal to make from some copper wire ("speaker wire") and alligator clips. Appropriately prefabricated cables are also available in electronics stores for a few euros.

6. Unfortunately, not all PCs still have a digital sound output (SP/DIF). If your computer offers a digital audio output, you should definitely use it, also in the interest of suppressing a hum loop. Reason: The digital audio signal is independent from the (analog) ground signal of the system.

7. The audio specialized trade as well as the electronics mail-order houses offer another solution in the form of the audio transformers, which effect a separation of the two audio circuits. The price range for audio transformers is very wide. While simple devices for use in the car, for example, can be had for around 15 euros, there are also professional devices that cost many times more.

 

So your PSU and computer is causing EM Feedback down the cable.Simplest solution, just get an other powerstrip, you can even turn that outlet into a double outlet as that distortion will go bleed off to earth rather than back up the wire of a parallel powerstrip. Unless you want to get into the rabbit hole of caging your PC and the transformers in your PSU, which frankly is beyond the scope of this forum.

 

In developed countries the neutral is grounded at the power plant.

 

Neutral is grounded at a substation or high load step down transformers, and usually at the entry point in a panel in dual phase current in the US, Mexico, Canada and Most of Western and Central Europe for houses built up to the mid 70s.

Although implementation differs on Neutral in Europe for new buildings that follow BS7671, where earth is grounded at site and neutral is grounded at the substation and breakers trip on difference in potential rather than load. This only applies to new construction since the mid 70s. In this system, the ground at your house is isolated from neutral, not connected to it, and thus carries relatively little current. It should have low enough impedance to carry enough current to keep you safe in the event of a fault, until the main house or breakers trip.

This ground impedance can also be assured, by connecting to the cold water pipe in the days when they were metallic - and it is tested for new houses, before you move in, modern pipes are no longer metallic and in rural areas water maybe ground sourced from a well, so new standards require 3meter earth rod for systems between 100 and 200 amps. A substation usually has an earth bank, multiple 5meter rods.

In a house protected by modern breakers - RCDs in the UK, or Europe (Substation Neutral) or on GFCIs (US local joined earth) - if you divert as little as 20mA from neutral to ground anywhere in the house, the breakers will detect the imbalance and disconnect power, in case that 20mA was flowing through you.

Reason is you can never enough earth points, they cost very little and add a great deal of safety and isolation. Power lines on poles and transmission lines are carrier only, or else you would incur double the transmission loss as you would incur a load due to impedance. The reason you ground substations or transformers is to isolate them in case of a failure. If they fail due to mechanical or load reasons they only affect their circuit leaving the rest of the grid intact, not because it gives you more civilized electricity. In large old cities where an incorrectly wired local earth can cause a good part of the city to burn down, the extra cost of assuring a solid earth at every substation is worth it because its better to assume people are idiots than to challenge them to prove you right. A local ground separate from neutral which bound to a substation or transformer is an infrastructure cost that is absorbed just to make everything a little more idiot proof.

Some people live in old houses, not everyone is as rich, as beautiful, or as smart to have been born in a civilized country. Some of us are still just hairless uncivilized murder apes. Especially in North America.

Lets assume your body is causing a fault, I for one would not like the deal with the impedance of 30 kilometer wire between me and the power plant before my circuit breaker trips. The extra cost of high load return wire that could handle an entire city all the way back to the power plant is also substantial.

 

I really should read what every one has written and correct any miths but it's late and I got work tomorrow so I'll be breif and if i remeber be more helpful tomorrow.

I'm a building services engineer in the UK by day, so what I say might not apply to other contries.

So power comes from the power station and runs to the transformer.

The transformer is a big metal coil with connection points at ether end and the middle.

Each end of the transformer will have a cable going to differant houses. the Middle will have 2 cables connected. the first gose to houses and the second gose to a metal stake in the ground.

The plug socket in your house will have 3 pins Live, Neutral and earth.

The Live pin on your socket connects via a cable to one end of the transformer.

The neutral pin in your socket will connect via cable to the centre of the transformer.

The Earth pin will also connect to the centre of the transformer. Tradisionally this would be via a stake in the garden and run theough the ground to the metal stake by the transformer, hence why we call it the ground/earth/Terre.

The idea behind electricity is the electrons are pushed and pulled bu the power station down the live cable and they want to reach zero. In a normal sistuation, the centre of the tranformer.

We have this earth pin incase there is a break in the neutral cable. the stake in the ground at the transformer make the electricity pradictable, we know it will go through the floor, to get back to the zero point of the transformer, if a cable is broken.

if you get a hum the standard power electricity is flowing though your audio circuit instead of down the neutral or the earth.

Old HI-fi use to need a earth linking cable because the quality of the cables supplying them often vairied, and in some cases the large power equipment such as the amp or the record player would have the electricity run in through there respective cables to supply them but out through the audio circuit and a nother bit of equipment like the tape deck to leave because it was a less resistive route. The earth link cable on the cases ment the least resistive alternative route was through the case and link cables, then out via a differant equipments plug.

The key thing to take away is Don't only earth one socket or all the earth leakage will run through the equipment to leave via that earthed socket.

If your haveing a problem with a earth then get and electrical engineer to look at it. the Problems solution can vary from a stake in the garden to a simple brake in a cable behind the socket.

The neutral and the earth pins are the same but a earth pin is ment to only be used as a safety back up. Lets just ignore PC's stupidly high leakage of electricity onto the earth cable.

 

So, I managed to solve this problem today, I opened my outlet and saw that the grounding cable was almost unconnected, reconectting it solved the problem
Seens like the connection of my audio interface to my receiver ground it

 

Glad to hear it's fixed.