Dedicated mains feed

Hi I am still pondering how I should wire my dedicated mains supply … the conventional wisdom is 10mm sq twin and earth… However, I have only one shot at this…and there are a small number of people on this forum … who have found such a supply not to have the desired effect… Thinking about ease of installation, I was wondering if running a dedicated 6mm sq twin and earth ring may actually be better … it would also allow me to link the hifi sockets in series with relative ease…and the impedance should be very low (if not lower than 10mm) any thoughts… or is this a bag of naughties??? any views…

I cant answer the 10mm question, but I’m sure others can. However I have a couple of thoughts. Are you trying to fix a specific mains issue you have? For example some people have reported a DC Offset on their mains, and therefore running a separate circuit will not solve this, so wouldn’t want you to be disappointed. The DC Offset issue might show in additional hum from your PSU’s and amps.

Also if you do go ahead and connect your sockets in series, I believe it’s best to connect the earth in a star method rather than serial. I suppose a unswitched single socket, then use a quality mains block would cover this.

I can’t answer any technical questions on the subject. However I recently moved my system to a new location in the lounge. I temporarily used a double socket from the main consumer unit rather than the dedicated CU and sockets at the original location. There was a definite drop in sound quality.
I got an electrician to remove the old 6mm cable from dedicated CU and run armoured 6mm cable externally to new location. Massive improvement. Better than the standard 6mm cable internally. I think this has something to do with better shielding and larger diameter earth cable on the armoured cable?? Anyway definitely worth doing for me.

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Full sized or even over sized earth would be on my wish list for a dedicated supply.
We used to install a dedicated oversized earth to IT cabinets in commercial installations.

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I was going to run a 10mm sq separate earth (or even 16mm I think this size may cause connectivity issues)…and yes my Nap500 has an unruly trafo which grumbles from time to time… Star earthing the earth is a good idea… hmmm

Yes, it’s a pig to work with and you’ll be swearing when you install it, but you only do it once so go 10mm, you’ll be happy you did.

Dave what system are you using???

When I was planning my dedicated mains I called Naim and asked them. They (Steve Hopkins) said that I should try to use 10mm if at all possible, so I did.
This does, as you say, raise the issue of how to get enough sockets for your system, as daisy chaining multiple sockets, while not technically impossible, is not ideal, and I wouldn’t blame any professional electrician if he refused to do it given that it’s well outside the design spec for a regular domestic wall socket.
The compromise I decided on when discussing this with my electrician was to split the 10mm cable into two under the floorboards using a Henley block, and send two short runs of 10mm cable up the wall to two unswitched double sockets, and this seems to work very well.
I did consider the idea of running two 10mm feeds all the way from the consumer unit, but Steve advised me against this, so I didn’t bother.
If I had to do it all again now, I would seriously consider running 10mm cable to just a single unswitched wall socket, and using a decent quality mains block from there.


I have 6m2 armour-core cable running to 3 MK unstitched sockets. The live and neutral are simply daisy-chained to one another but the earth is set in an equal length star arrangement. I have two unswitched MK sockets close by on my internal house ring-main and have tried the system on both circuits. As expected the dedicated circuit is miles better.

A mate was so impressed he had his system done but his sparks gave him a 6m2 ring rather than a spur. Again, he had a large jump in performance but it’s difficult to know if the ring or spur is better?

If you are getting you sparks to do the work why not ask him to run two 6m2 runs then you have the option to crate a ring or keep it as a single spur?

I’ve also noticed that the music works mains block is wired as a mini ring main i.e. a loop is created inside the block. Not sure if this is responsible for the increased performance compared to the more traditional daisy-chained blocks?

I’m very happy with how my circuit sounds but there may be some additional screening advantage to using armour-core?

I have three 10mm2 runs from a separate consumer unit to three double unswitched MK sockets. I have compared this to a Music Works distribution block in one of those sockets and… I couldn’t tell any difference.

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Richie - Whether you go for a 6mm2 ring or 10mm2 radial, either is going to be better than sharing the hi-fi on an existing ring with a number of daisy chained sockets and various other electrical equipment. You can spend a lot of time thinking about these things but personally I’d keep it simple and go the 10mm2 radial route. If you have a difficult cable run from the new CU to where the Hi-Fi is located then get a couple more runs put in place when the initial work is done to save having to run more cables if you decide on a different approach later.

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I think I may go for a 6mm dedicated ring…and daisy sockets in … and run a large dedicated earth. .

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LP12 & KDSM, 552DR/500DR, Titan 606s, lots of ChordMusic.

That does make sense, for instance, the MK double socket, indicates a terminal capacity of 2 x 6mm2 cross sectional area, (CSA) and if both cables only go to one point it is technically a radial made up of two parallel run cables total CSA = 12mm2. If you then want to add another socket at a later date you can open the circuit up to form a HiFi dedicated ‘short ring’.


Having just run three radial circuits in 10mm from a new dedicated CU I’d say that if you are going to the trouble of doing this you might as well do it well.

10mm isn’t that bad to work with and the MK switched double sockets recommended by many on here accept the cable fine. I have three doubles stacked fairly close together and they went in fine.

Given that a major part of the cost of installation is electrician time and that running 10mm rather than 6mm or 3 circuits rather than one is fairly minimal just go for it. Compared to the cost of even a “low priced” Naim upgrade like a Powerline or HiCap it’s a massive upgrade (honestly I was very sceptical) for not so huge an outlay.

Also while you have the floor boards etc up why not run some shielded Cat6a as well? I’m about to decorate our room and getting this done now ensures I don’t have to decorate again in a year or two when I’ve added some more boxes :wink:

Good luck!


I’m speculating here that a ring arrangement does not give you a star earthing pattern in the way that a single feed or a suitably wired mains block would. The earth (and the live and neutral) would just be daisy chained from one socket to the next, unless you instal a separate earth wire to each one.

Well…I was intending to install a 10mm earth…and then use a Henly block or bus bar to take 10mm earths to each socket…my 10mm earth would be terminate quite close to the 3 switched socket outlets…and then split equally in a star earth arrangement.

Yes, I guess that would do it. In fact, it does it in the same way that the live and neutral are started in my arrangement as mentioned above.

When you say switched…do you mean unswitched!?

I had three runs of 10mm cable run to three double unswitched MK Logic Plus sockets from a seperate consumer unit earlier this year, and am now loving the improvements that bought to the system. My electrician remarked how easy it was to wire the sockets up, and they will now become his favourite socket. I don’t know how easy things were at the consumer unit end, but judging by the lack of swearing, I’d say it wasn’t too bad.

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Yes a slip…