Radial wiring

As big as you can! 6mm id have thought would be ideal. Any bigger and you'll struggle to get the cable into the socket. 

My garage is in the early stages of being converted and I too will be having a dedicated spur for the hifi. I'll be using 6mm 

Finkfan posted:

As big as you can! 6mm id have thought would be ideal. Any bigger and you'll struggle to get the cable into the socket. 

 

Agreed. At the risk of stating the obvious, have a dedicated consumer unit fitted as well with something in the order of  40A  circuit breakers.

Yes another vote for 6 mm cable and 50 mm² Earth wire.  

Just keep in mind that how the 6mm cable is installed will affect the circuit breaker rating. 40A is fine if it's just clipped to surfaces, but in trunking or plastered into a wall and you'll have to drop down to 32A. Your electrician will advise you on this anyway 

This will be an interesting read Simon,  sometime in the next months my garage is getting demolished & rebuilt & that will include replacing the consumer unit & an opportunity to modify my existing audio supply.  

I'm interested in how you (your electrician) work out your dedicated radial earth.    If I remember right you had isolated the audio/radio power supply & it enabled you to have an earth (as in planet earth) spike/plate & not be tied into the TN–C–S (PME) system I believe you have.    

10mm sq.

I've pared this thread back and will be watching carefully.  Please don't post mains install recommendations that may well not be to safety code requirements in all countries.  Simon is UK based, so any recommendation here must comply with current UK electrical code.  Thanks.

Completely agree! Simon is doing the right thing. Use a qualified electrician. 

Simon-in-Suffolk posted:

Ok forum, our family electrician has agreed to wire me a radial weekend after next for the audio equipment... So any recommendation on gauge of wiring from the consumer unit?

I have 2 x 10mm squared cables feeding 2 x twin MK switchless sockets. Can't say the difference in sound quality was worth the effort or cost. I found the difference only marginal and if I was blind tested I doubt I'd be able to tell.

Ken

Thanks for the feedback chaps, so I will ask if we can go 6mm live conductor as opposed to regular 4mm live conductor on a 32 amp radial. As there will be some trunking in a hall area for the cable routing there may be some physical constraints.

i live in an older cottage type house and so the consumer board is inside as the supply is fed over head directly to the gable of the house. The consumer unit has recently been replaced ( when removing PME Earth) so I will be using new existing single consumer unit  as it has  free RCDpositions available. (This or a single 13 amp spur was a consideration when it was being installed)

Mike as far as the true earth, yes that supplies the whole house , with a master earth electrode for the property outside that connects to the consumer unit as opposed to using PME. The new radial won't affect this in any way.

Cheers

Simon

Simon, I'd strongly suggest that you split the meter tails and install a dedicated small consumer unit with 50 amp breakers. Then run 10mm2 cable to unswitched sockets. Make sure the earth from the new CU goes back to the meter and does not piggy back off the existing consumer unit. This complies with current standards. The minor extra hassle of the separate unit and thicker wire is very worthwhile. Feel free to mail if you'd like any further info. 

HH I hear you, but recently had a similar arrangement as you suggest removed to meet with modern requirements when I removed my PME earth, and had an investigation into nuisance tripping,  so I have new approved single combined CU. I am loathed to change it again, as I say its internal and has to be decorated around.. and of course this includes master supply switch. Perhaps your setup is more optimal for PME as opposed to true earth such as mine.

10mm cable makes a substantial difference to sound quality regardless of the type of earthing system. I had 6mm radials and when I upgraded to 10mm radials the difference was immediately better, and got even better still with burn in. 

6mm is the easier option but you will be hugely rewarded sonically for installing 10mm.

Talking to my friendly electrician ( who has wired recording studios and has recently done work for a very well known singer song writer with red hair who grew up in Framlingham, Suffolk), one key thing is the mains impedance.. And that is determined in part by the cross section of the live conductors X the cable length run. Out of interest when you used 10mm what was the cable length to the consumer unit?

I am not expecting my radial cable run to exceed 7 metres.

Simon

Simon - a word of caution. Professional recording / sound studios tend to approach music replay a little bit differently to audiphile playback.

What matters for the studios is: reliability, robustness and ease of connections. Not the last fine-tuning of a sound. Example: Neutrik's speak-on is a robust plug, which cannot be pulled out easily, thus damaging a 100W tube amp, when it's running at a proverbial 11 and a speaker suddenly gets disconnected. Used to happen a lot on stages and in dark studios. It was chosen for that purpose, not for its sonic qualities.

My point being: what may be good for a professional studio, may not be suitable for a house.

Adam understood, but the this electrician (and his firm) does commercial and domestic, and from what he tells me, some of the commercial requirements can be as picky if not more so as some of the more OCD consumers out there.. and perhaps on this forum   Also of course in the UK at least one is bound by regulation.

Mains impedance is critical and Naim confirm, according to Richard Dane recently on a thread on 'line condiotners', this has a bearing on performance.

Finally I would say when I worked for a while for the BBC in my youth, I remember working and talking to some of the sound engineers at the then new Maida Vale sound studios, and they were all at least as obsessive to those on this forum.. and in part that experience fuelled my interest in higher end hifi.. I don't think there is such a discrepancy .. At least in my experience..

Simon

Simon, The cable run was ten metres, so it wasnt a length issue. The 10mm is just so much better. In my current house the mains was closer to the lounge so I now have 5 metre runs. I had the joy of hearing the upgrade again too as it took me a few months to get around to reinstalling the mains at my new home. In the mean time I had been using the house ring main circuit. When rewired to 10mm radials it was a real wow moment again, even though I knew what to expect. 

Interesting, thanks for the reply... I'll add it to the discussion with my sparky.

He Happy, what sonic improvements were there with 10mm over 6mm? 

When my hifi is moved it will only be 2.5m from the board. If 10mm is so much better then I'll have that fitted

Hi Simon, Finkfan

DB manages to struggle on with a mere 2.5mm2 radial for his system and appears to survive, so a 2.5mm2 radial is no slouch.

I used to have a 2.5mm2 radial and that was a real step up in terms of dynamics and musical engagement over our ring main.  And that was with a circa 20m cable run.

The office system now runs off a dedicated 4mm2 radial of circa 10m length and is awesome.  The power supply is certainly not the performance bottleneck for this system (DAC-V1 + NAP140)

The living room system is powered by a 10mm2 dedicated radial of around 25m length.  My logic for this one may prove to be the most helpful for you.  For a radial of this length, the choice came down to either 6mm2 or 10mm2.  The cost difference was far less than the cost of installation time, so cable cost was not a material factor.  

What was critical, was deciding how to get the power from the end of the radial wire into the Naim plugs.  This was either a bank of wall sockets or a single wall socket (okay, an MK dual unswitched socket) + a Musicworks distribution block.  If you want a bank of wall sockets, then 10mm2 cable is too fat to make the connections between all the wall sockets, even with MK sockets.  With 6mm2 cable, an electrician can just about connect them together.  If you opt for single socket + a distribution block, then 10mm2 will be fine into an MK wall socket.

In the end, I opted for the 10mm2 cable + a Musicworks distribution block.  We then connected another wall socket up to the main one but had to use 2.5mm2 cable from the main one to do so.

A 6mm2 radial of 4-7m length will probably sound indistinguishable from a 10mm2 one due to the minimal impedance of either option.  The cost difference will be minimal too.

Hope this helps, a bit, FT

Simon,

I used 10mm sq screened mains spur cable from Mains Cables R Us (MCRU).  I agree with HH that you should install a separate consumer unit otherwise a lot of the RFI from your other ring mains will leak into the new spur.  Russ Andrew's web site has a lot of useful guidance on what to do for UK installs.  I also purchased their consumer unit but did need to change the MCB as the one they included kept tripping when powering on my system due to current inrush.

If you've not been using a dedicated spur/ring main before prepare to be stunned as to the difference it makes, it's huge!

Simon, I seem to remember on another recent thread you were in favour of using a ring rather than a radial. Any particular reason for favouring a radial now? I can see that there are practical considerations, such as half the amount of cable, and less trunking, but just wondered if there were any design issues here? 

ChrisSU posted:

Simon, I seem to remember on another recent thread you were in favour of using a ring rather than a radial. Any particular reason for favouring a radial now? I can see that there are practical considerations, such as half the amount of cable, and less trunking, but just wondered if there were any design issues here? 

I have the same question,  since i have a simple ring cable scheme, albeit with much smaller gauges of 2,5mm,

Regards

Roberto

Graham Clarke posted:

Simon,

... I agree with HH that you should install a separate consumer unit otherwise a lot of the RFI from your other ring mains will leak into the new spur...

Hi Graham

One question on this point, if I may?

If there is RFI on the outlet side of the consumer unit, how does the consumer unit filter this RFI out before it reaches the mains supply cable?  I simply don't understand this point.  The consumer unit consists of bus bars and circuit trips but no filters that I am aware of.

The benefits of minimising input impedance to the hifi make perfect sense.  We have both put our money where our mouths are on this one!

However, the use of a separate consumer unit as some sort of RFI filter may not stand up to electrical engineering scrutiny, unless someone knows otherwise.

Best regards (in a non-confrontational or controversial way), FT

Foot tapper posted:

Graham Clarke posted:

Simon,

... I agree with HH that you should install a separate consumer unit otherwise a lot of the RFI from your other ring mains will leak into the new spur...

Hi Graham

One question on this point, if I may?

If there is RFI on the outlet side of the consumer unit, how does the consumer unit filter this RFI out before it reaches the mains supply cable?  I simply don't understand this point.  The consumer unit consists of bus bars and circuit trips but no filters that I am aware of.

The benefits of minimising input impedance to the hifi make perfect sense.  We have both put our money where our mouths are on this one!

However, the use of a separate consumer unit as some sort of RFI filter may not stand up to electrical engineering scrutiny, unless someone knows otherwise.

Best regards (in a non-confrontational or controversial way), FT

FT,

Nothing wrong with your question

I'm not an electrician or particularly knowledgeable in this area so you'll have to take what I say with an pinch of RFI reduced, low impedence salt.

My understanding is that the consumer unit doesn't filter this out.  The RFI is generated by devices (fridges, freezers, even hairdryers!) on the house ring main and this can then find its way into other devices.

By wiring a second consumer unit in parallel with the original with both connected to the commercial feed this is either reduced or removed.  I'm not sure how.  Maybe the RFI attenuates across the additional circuit?

While I may be rubbish at explaining the theory, for me the proof was in the listening.  I took a punt in getting a separate spur installed (the electrician I used thought I was crazy) but based that on feedback from my dealer and others on here.  The difference was huge - much better clarity and far easier to follow vocals and the meaning of them.  I guess a factor here is that you're not improving a single box (as you would with a single box upgrade), you are improving everything in the reproduction chain that takes AC power.  After the Statement Pre and the SL cables I'd say it offered the biggest single incremental improvement out of any change I've made.