A forum member that I know recently had a dedicated supply fitted for his hifi by a reputable Electrical Contractor. He’s on a TNC supply like most of us who don’t live in the middle of nowhere. The installation includs a dedicated earth via earth spikes. It can be done safely (Hot tubs supplies are usually earthed via rods).
I asked the electrician whether he could improve the existing earthing arrangements for the HiFi radial, which include a dedicated Hagar CU with 2 different cables going to a double and a single unswitched socket in the room.
I did mention that many others who have done such a radial have got a good result in terms of EM noise reduction in the system from adding a dedicated earth, but he did not recommend doing it.
I cannot remember his reason for making that proposal, but as he is a qualified electrician I accepted his decision.
It’s possible that he didn’t want to do the extra work.
Or it may have been because the outside meter box is embedded in the house wall where the boundary to the neighbour’s property is only about a meter away.
Or some other reason, e.g. he may not have fitted many earth rods - and he certainly had never done one for a HiFi radial - although he has fitted one or two HiFi installations in the past.
If there’s a good chance of getting a good improvement in SQ safely and within the electrical regulations I would do it.
I love in an 8 year old house in small city - but not sure whether it’s a TNC supply - how would I know, short of asking my electrician?
I must admit its a long time since I did my Electrician course (then never practiced it), but I think the hot tub is different as its outside the building, but as the hifi is inside, with a separately earthed circuit in the same building, there are fault conditions that can create a potential difference between the earth on your HiFi and the earth in the rest of your house.
From what I have just read, it is a little confusing, and perhaps most electricians would shy away from it.
No doubt someone more up-to-date on these things can confirm, as regulations do change every few years.
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Think sparkies can earn quite a bit these days…
Greatly depends on country and code I suspect.
I had 3 phase in, with 2 phases and one earth spike to centre tap for the main house. The earthing arrangement to the sockets there is that earth between sockets cannot join earth from things like aircon or ovens etc and must be isolated up to the CU. There are 3 hifi circuits (not the main one) on this CU and those have their own isolated earth up to the CU, not sharing with anything else en-route.
The third phase is for the hifi with it’s one earth spike to centre tap (though with only one phase so there are no double voltage circuits really). That is a simple arrangement of one dedicated CU, with one breaker, and one earth, and one set of power and earth going out to one socket.
The important thing is, when designing this, I sat down and diagrammed out what I wanted starting from the 3 phases coming in all the way to the plug sockets. Sat down with an electrician who basically said, “this is what you want, but according to code this is what we can actually do. Here are some suggestions to work around that and stay within code.” So I’d suggest doing the same. Define what you want and let a local electrician tell you what you can legally/practically have.
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This is what my Electrician told me. It can be done safely on a PME supply as long as the installed earth can carry a fault current in the unlikely event that there’s a broken earth coming from the sub station transformer that feeds the house (and several other houses sharing that supply) . The hifi earth must be bonded to the earth bonding point at the hifi consumer unit with a large enough gauge earth cable (16mm works) and we need sufficient earth spikes installed correctly ( I have 3 x 2m running in line 2m apart) to reduce ohm impedance to an acceptable level. One spike just won’t be enough. I also as part of my early morning routine water the ground above the spikes. My installation was signed off and PeterR had a similar installation done a few months ago which was signed off. So it can be done.
As for the benefits to my hifi sonically. The dedicated earth provides at least as big an improvement as the fitting of a dedicated supply via a tailed off circuit breaker. Of course I accept that it’s been easier for me to have this work done as I worked in construction as a tradesman, then a contractor and now own a small property portfolio all of which were renovated prior to being rented out. My last three homes have had full renovation works done and I had dedicated supplies for my hifi installed in all three with no issues.
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In my case a 16mm earth cable was connected from the earth bonding point in the outside meter box where the supply enters my house to the earth bar in the HiFi consumer unit.
I have 2 radials:
Lapp Olflex Classic 110 CY 10mm to Furutech (G) single socket that had a circuit impedance of 0.04 Ohms (and an Earth loop impedance of 0.07 Ohms).
And a Belden 83803 (12 AWG) cable to an MS HD Power (G) duplex socket that had a circuit impedance of 0.08 Ohms (and an Earth loop impedance of 0.06 Ohms).
The Earth loop impedance of the house ring main was 0.41 Ohms.
I have no idea whether any of these measurements has any influence on SQ, but the fatter cable has lower circuit impedance, which seems to be a good thing.
I haven’t done careful testing of SQ impact of the circuits, but when I recently plugged my ND5XS2 into the ring main SQ took a dramatic nose dive.
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That’s a really nice low impedance Jim. Of course impedance level is only part of the equation. You are still dependent on the PME to dissipate all that noise that your lovely neighbours are generating coming into your home. I find that my hifi earth (I think it was measured at between 10 and 20ohm) must be acting as a “drain” for much of that or why the sonic benefits? We can be comforted knowing that most electricians don’t seem to fully understand the science of it.
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I don’t think it’s possible to fully understand the relationship between SQ and the physics of a system.
Not even Einstein could do that.
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Agreed. Burn in being another example. Also I unplugged my system during recent thunderstorms and it took a week for it to get back to 100% performance (Jas Gould told me that the consensus at HQ is that the S1 takes 3 weeks to return to it’s best after a lengthy power down 
). I don’t want to believe it/them but my ears tell my brain that it’s a real phenomena.
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That’s good to know. I’ve come across some very good electricians, but also come across who just like to do a basic house re-wire with little or no complication. Going back to my electricians course, there were a few people that really struggled with basic maths, and particularly basic equations such as V=IR. Of course when you take the exam at the end, you only need to score about 60%'ish to pass, so they did get through. In many respects bringing in “Part P” registration does add some confidence in your electricians work.
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@GadgetMan
Absolutely agree I’ve had various trades here recently and they want to do as little as possible for maximum bucks.
Unless it’s worth getting yourself ripped off they’ll find an excuse not to do it. 
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Thanks all, really feedback and armed me with the right questions to go and ask my electrician. I can confirm I have TT Mains supply (Separate Neutral & Earth) as opposed to TNC (Neutral and Earth Combined).
The opinion of my electrician is that given he has just installed a brand new Earth spike from the main consumer unit, he doesn’t think that there would be the same benefit installing a dedicated spike for my hi-fi as there would if I was on a TNC system. However, it is something he would do if I wanted - views?
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I feel that just about all of the construction apprenticeships are watered down now. For example the number of young plasterers that can’t rough and skim coat a wall is shocking. They just skim. I don’t suppose there’s much call for earth spikes these days as for the last 40 years all new builds have PME supplies. Also obsessive hifi nuts aren’t the norm.
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Go with your electricians advise IMO. You are very fortunate to still be on a TT supply. Enjoy!
It’s exactly like I said in my last post they make you pay for extra for it and obviously he wouldn’t do it if against regs.
My house has a spike as it was discovered many years ago that on checking when we got a new meter that the earth was non existent 
Everyone tells me how lucky I am to have a spike so I don’t mind.
There are lots of people that rave about it.
Thanks - Going back to my earlier post, I live in a 1930s Art Deco era house and much of the wiring (and plumbing) dates back to then. We had the place rewired when we moved in, just to bring it up to modern standards, but the extension afforded the opportunity to add a dedicated radial
Electrical hurdle overcome, next challenge, how do I convince SWMBO that a Naim Fraim really is an Art Deco feature and would be in keeping with the house…?
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Good luck with that Mike 
Just to add my two cents and I confess I have not read all posts. I understood that the quality of the copper was the essential thing. Something to do with purity and oxygen content. I recall the supply problems during the Zimbabwe turmoil. Also the eddy currents have some effect and finding a true earth/ground is not as simple as sticking a rod in the ground.
Then again I may be wrong and I have not delved into the topic practice.
Thanks Nobby - My electrician said the same, I opted for 4mm2 Shielded, Oxygen Free Copper from MCRU - It will be a few months before we are finished and everything is installed and tested, but I will post results on here as soon as I have a verdict