Mains sockets and star earth - can anyone explain?

The vendor of my mains isolation strip advised me the following by email:

To avoid any unwanted grounding problems and to get the best performance out of your system you should power all electronics of your system, no matter if they are wired with or without a grounded cable  out of one wall socket (starred earth reference)

Can anyone explain what this means, especially with reference to starred earth?

I now have my amp plugged directly into one socket of my 2-socket wall plate, and my isolation strip (for my sources) plugged into the other socket.  What difference does this make to earthing?  Surely, a neighbouring wall plate will have its earth connected to every other wall plate in the room by parallel wiring between the plates.

Note: all my cabling is shielded with the shield connected to the earth pin.


You’ll probably receive a lot of information and advice.

Surely, a neighbouring wall plate will have its earth connected to every other wall plate in the room by parallel wiring between the plates.

I’ll start with this concept first. If you currently have no hum or noise, then you’re lucky.

Your audio system needs to have one common ground that is wired directly to your service panel. These wall receptacles connected together will not have a direct path to ground at the service panel. By plugging your system into this rat’s nest of wiring you are sharing your audio with all the appliances and lighting in your house. This adds noise to the AC line which is audible through your speakers. If these wires have different ground impedances when they meet at the circuit panel, a ground-loop is created. You’ll hear a 60Hz hum thru your speakers if this happens.






Surely, a neighbouring wall plate will have its earth connected to every other wall plate in the room by parallel wiring between the plates.

In the US, it's much more likely that the wiring is done in series, and that's the problem. A dedicated line avoids all those extra connections.

What's important to avoid ground loops is keeping all grounds at the same potential. Plugging everything into one outlet is only one way to achieve that.

A star ground is a pattern of 3 or more grounding rods all connected together and connected to the earth ground terminal in a power distribution box. This is usually a more effective ground compared to a single point ground which is common in housing in the US. You should be able to find plenty of information on grounding methods on the net or check out the book "Grounds for Grounding" or find out what the traditional phone companies used in your area.

Unless you have dedicated wiring for your stereo it has short comings, ground loops are just one of the possible issues. Voltage drop is probably a more common issue, wiring is probably to small creating a weak link in the performance.


starred earth (ground)

Think of your circuit breaker box as home base, and a single point. Each individual circuit in your house (apartment, condo or office building), or run of AC wiring, ends up terminating in this load center. This is also where all of the grounds (including your ground rods and utility pipe grounds - water/gas pipe) to these circuits terminate. If you saw this single point in your circuit breaker box (even though it’s a bus bar), with all of these grounds attached, it would kind of look like a star. Hence the reference.

Star grounding can also relate to audio gear AC power connections. If the gear has 3 prong plugs, when plugging them all into a wall outlet, or power strip, the 3rd prong is the earth ground. You want only one ground connection per piece of audio equipment, hopefully on the same circuit, unless you have separate circuits with dedicated isolated grounds. Connecting audio gear together which is on different circuits can create ground loops, since the grounds on other circuits may be at a different ground potential. In that case, if you’re connecting via balanced XLR connections, it’s important to pay attention to pin 1 of the XLR connection. In that case, to prevent a ground loop, pin 1 should be lifted on one end of the cable.


A star ground is a pattern of 3 or more grounding rods all connected together and connected to the earth ground terminal in a power distribution box.

Having dealt with lightning strikes to radio broadcast towers on an annual basis for many decades, and electricians installing ground systems to divert these strikes, the better choice is to connect all ground rods together (not as individual runs to the single point of reference), with *one* connection to the single point of reference. You can also form a loop of ground rods around a building, with both loop ends tied to the single star point.

Hi @dpop - many thanks for your explanation, and the time you put into it.

It certain beats the following DM I received from @riley804 


do you have google ?

if you google your title, you will find your info that you are looking for.



Are you being sarcastic? If you are, please have the balls to be public about it on the thread.



maybe if you weren’t so lazy, you could have looked this up yourself and learned something


better ?

@riley804 Asking advice on earthing and powering an amplifier is surely the whole point of a forum.  If such a request upsets you so much, best not to scan forums.

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Welp, that's it then: let's all quit the forums and forego this community's experience, valuable insights and advice, and instead rely on Google as our audio oracle. Much easier than engaging with others.


and again, use the grey matter between your ears and look stuff up….you have the internet, use it instead of getting the answers from others. you might actually learn something for once

Not fair and not deserved. Sounds like he’s not going to learn anything from you except how to be a           . We all have bad days sometimes, so if you’re experiencing one, I hope it improves for you. We’re not in 3rd grade here cheating on tests.



Not fair and not deserved.

if he would have kept the DM between him and i , this wouldnt have happened, but he decided to bring it to the forums .


i am not experiencing a bad day....but i am not going to sit here and take this from him. yes there was sarcasm in my reply to him and if he is that thinned skinned that he cant take it, then i feel sorry for him. if he was with a co-worker and they told him to go use google, would he react the same way he did to me ? i bet he wouldnt and would more than likely, laugh it off.




I fully get what the forums are for.....


when we all were younger and in school and were doing our school work either at home or at school and we asked for help on something because we didnt know the answer to something, did your parents or the teacher give us the answer to the question ? no, they tell us to do look up the answer ourselves because if they give us the answer, then what did we learn ? the same thing applies here....the OP asked a good question and if he would have done a google search using his title , he would have found plenty of info to read.

how is that a few members could give the OP info in this, but the OP cant take time to look it up himself?


i like how other members of this site can make comments like this all day long and nothing is said....but as soon as i make one, its a whole different story.

so one either has to agree with what other members say or just dont say anything at i am not allowed to have an opinion of my own . is that it ?

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