10mm dedicated mains supply, but is a separate CU really necessary?

Hi Phil, the situation here is in slow progress, i have a coil of SY cable but it’s not actually fitted yet. The floorboards are presently up in one of the upstair rooms to allow a routing though to another bedroom (floorboards will need to come up there too) and then route though the house wall to the garage where it will turn down the wall to arrive adjacent to other side of the wall to where audio situated; and then a simple case of though the wall to connect to a duo of unswitched 2-gang sockets.

Simitainiously another 6mm cable will travel along with the SY to the garage, and will terminate at another CU to supply garage sockets, lights, oil burner, and fuse for 4mm armoured cable to go outside to a shed. However the SY cable will bypass all this.

The SY cable will have its own fuse within the main household CU, so it won’t be as dedicated as i’d like due to where the meter is rather awkwardly situated; having discussed this a few times with my electrician friend; it isn’t reasonably possible (without spending thousands on relocating the meter).

I see the SY cable audio supply more as a sideline job in an ongoing effort to up-rate the household electrics, a more pressing concern is disbanding some rather dodgy pre-inhabitant amateur wiring by way of fitting a proper garage CU, and a new shed CU too, having all this safe and correct to present regulations.

My house doesn’t need a rewire yet, most of it is fine, but i am interested and pondering the option of replacing my main CU with an RCBO type. My present main CU was fitted in 2014 so isn’t that old, but i’ve never really liked the way a group of fuses bundle into an RCD, and in theory the RCBO board should make fault finding a lot simpler, and maybe that anti-surge protector is a good thing if one has a lot of money invested in audio.

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Update 3 - The sparky turned up with his mate at 9.30am and things appear to be going well so far​:crossed_fingers:t2:I say that as I’ve not heard lots of cursing, moaning etc.:rofl:

He has managed to install the new CU in the electrical box where the other ones are so I think he is happy about that rather than using a work around he had previously suggested.:+1:t2:

They brought a large reel of 10mm2…jeez that stuff is thick😀 Mrs CTJ rolled her eyes when I informed her of what I was doing…I’ve not told her of my masterplan😁…yet!!!

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Best of luck……it’s been nice knowing you, if the wife throws you out🤞🏽


Ask if they can polish/clean the ends of your mains fuse too, if they have removed/need to remove this (if you haven’t already)?

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Update 4 - All fitted and I must say they have done a very neat job. Mrs CTJ has not thrown me out yet so we’re all good👍🏻

Only issue is they have put a switched socket in instead of the un-switched one I specified. Not to worry I am getting them back soon to sort an issue with our garden lights.

As to the sound, initial impressions are that it’s giving a wider soundstage and appears to offer more detail.

I read on another thread about some changes the poster made that allowed him to hear birds singing at 23 seconds on Taylor Swift’s song Exile (great song BTW).

I immediately played it and couldn’t hear them🙁 I then re-jigged the set up of my Innuos Zenith Mk3 utilising the excellent Sense app and I am
pleased to say I could then make them out.

When I streamed the track again today it was almost like the birds were in the room with me😀

I realise that I need to be careful of confirmation bias so if anyone can recommend any music with difficult to hear parts in it I would be very grateful.

All in all I am happy that I have had the dedicated mains fitted and feel sure as it burns in that the sound will improve further.

Once again, I appreciate all the help and advice given by others in the forum. I would not have known where to start otherwise.:clap:t2:


Great it worked out, and you are still alive. I would not fuss too much on music to prove it’s better……just sit back and enjoy. On a different thread a few of us are celebrating changing 13 amp fuses, so a dedicated mains should be OK.

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As it appears, I’m having to rewire my new flat. Where else do I come to find out if there is a ‘way’ to do it. Went back and forth with my sparky who thinks I’m crazy but will do it anyway. He will turn up tomorrow so let’s see what happens. Next will be to upgrade my gear.

Out of interest, as a Zenith owner, what change did you make?

I originally had both the Nova & the Zenith connected to the router.

The change I made was to keep the Zenith connected to the router plugged into the LAN port.

The cable previously going from the router to the Nova is now connected from the Zenith (streamer port) to the Nova as it should be.

I realise that most if not all owners will have already done this, but I hadn’t🤦‍♂️ It was like lifting a veil👍🏻

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Sorry to jump on this thread, but I’m putting in a dedicated radial next month and need to buy some components.

I’ve read a lot of these threads and tried to put together a list of what to buy. There are a lot of option, but I think it might just be easier to go for the Russ Andrews CU and their recommended MCB and RCDs. It’s a Hager CU.
Anyone used this?

I’m also not sure what cable to buy? I may go for 6mm2 instead of 10mm2, but is there a particular make that is best? Can I just use whatever the electrician has? Again, Russ Andrews do a cable, but it’s very expensive (and only 2.5mm2?).

I need to get my wallet out and start ordering stuff.

Note: the HiFi cable will be run with a cooker and underfloor heating cable, both 6mm2 I guess. The HiFi cable will also be chased into a wall for part of it. I will have only 1 radial and a double unswitched socket at the end. Probably an MK one.


Hmm, one issue with the Russ Andrew CU is that you might have to run it as a ring? Anyone know if I’m right?

Many thanks,

RA prefers to run a ring from the CU with lower CSA cables instead of a radial. It’s a standard CU, just fitted with ‘uprated’ components so it’ll be up to you and your electrician whether to wire it as a ring or radial circuit.

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Thanks @james_n that what I assumed, until I read this review about their CU

“Yes, I recommend this product.

“Invisible Rcd”

After a month of trouble free operation in my AV / HiFi set up - pre 7 power amps & analogue digital sources, I can report that this RCD/MCB combo has NO audible detrimental effect, NO reduction in dynamics and if anything enhances detail & hence musicality. But 4 stars only because it lacks the internal blue neutral return wire to the RCD. Running two existing 6mm dedicated radials from the 32A MCB.”

Although looking at it now, I talks about 2x radials not a “ring”. I also don’t really understand the issues anyway.

I’m way out of my depth on this, but I know the electrician will just buy whatever he can get at the time, and not “what’s best”.

When Steve Hopkins was running Naim support I asked him about dedicated mains, and he urged me not to use 6mm instead of 10mm when I suggested that it might be easier. So I went with standard Prysmian 10mm T&E which is what many electricians would use.


Ive tried both 6mm and 10mm. 10mm was noticeably much better. Either will need a few weeks of use to sound their best though.


Or the price!:face_with_peeking_eye:

My main Consumer unit and its various RCBOs should be here tomorrow, but I didn’t order the separate Hi-FI Consumer Unit.
Do I get just a bog standard 2 way Unit, without Serge Protection?
And to confirm the RCBO type for the 10mm cable.