Dedicated Radial Plan

If he won’t i will find another sparky, but he should be OK with it. Its an easy job, the meter is in our boiler cupboard which is behind where i want the socket…….about a meter of cabling. Just drill a hole, and do the connections………probably less than an hours work.

I’d not underestimate the role of grounding in the overall system design. You’ll have a single phase supply from your DNO and then determine how you plan to create your circuits accordingly. In my case I’m lucky to have my own TT (Terra (Earth) to Terra (Earth)) earthing arrangement, I’m in a rural location with overhead supply from a transformer located a short distance away on my road.
You can confirm what arrangement your supply has by checking the meter box and cabling coming in from your DNO. All consumer side wiring will be grounded to the same point, regardless of if you have one consumer unit or 5.
Bare in mind also that modern MCB’s and CU design provide both high levels of protection and circuit isolation, assuming you’re UK based, I’d be focussing on something from Hager or Schneider Electric as they have very good layout options and DIN rails and their MCB’s are well designed and of a high quality.
You can install an RCBO or AFDD for each circuit to give high levels of protection for each circuit.
I did a similar exercise recently and fitted Type A RCBO’s for each circuit. I’m not personally a fan of splitting off the meter tails and having multiple CU’s, modern CU/MCB design and capabilities should mean that approach is redundant. You can populate a unified CU that can incorporate an SPD, MCB, RCD and even Arc Fault Detection in a simple and integrated way.
My feeling is the whole multiple CU approach came from a time when CU/MCB capabilities were more constrained and incorporating protection and isolation features was more costly and complex so simply splitting everything off and doing it in a separate CU was considered making the best of the limitations of the components in the system design.
In terms of any socket radial for your hifi, I’d be inclined to do that on a single radial and with the sockets connected to each other in series, the challenge then becomes fitting the 10mm cables in to the back of the sockets so using surface mount back boxes gives you some space to work with and you can then connect each backbox to the next using uPVC conduit, chasing it in/through walls is more disruptive and costly, factoring in the Electricians hourly rate if nothing else.
I used 6mm T&E as a happy compromise, my system isn’t worth enough to worry about what I’m missing by sacrificing that extra 4mm of copper.

Interesting post M. I would counter with the thought that the majority of us with a dedicated CU and multiple supplies for our hifi have heard the sonic benefits. Improved Resistance and impedance are clearly beneficial.

The “grounding” issue is another matter and I have read a lot of conflicting opinion on whether a dedicated one for our hifi actually acts as a drain for unwanted “noise” or not be it from our home or other properties on the same grid if our supply is PME.

I envy you being on a TT supply and my ideal final home will be in a rural area with a close by underground stream. If so I will look to have the largest possible copper plate buried close to it for an obvious purpose!

If nothing else it means you are in control of the grounding and isolated from your neighbours, interference and noise can come from multiple sources of course, including those outside your control or influence. I’m also not pushing this to levels of experimentation that others are, I’m just providing personal perspective, in others situations a better setup may well apply of course.
I’ve gone for a setup that is simple and with high levels of protection for the whole installation fundamentally, I would say that my systems run entirely silently, at my old house which was in a town centre, near a train station and had a different earthing arrangement, I did get transformer hum, even with all the separate wiring and CU setup as others typically lean towards.

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If one has 2 bus bars in a CU with 2 radials into 2 sockets would the electrician wire each radial to a different bus bar?

Or would the purpose of having 2 bus bars just be to increase the surface area of the contact with both radials?

I think it’s the latter – I’ve never dug in to this, it’s just something which came up many years ago when discussing wiring et al (as these folklore matters go :grinning:).

Having fitted my new CU c.20 years ago (scary!), I asked him to post-fit a 2nd bus bar (only a bar metal plate). He bought one and then found it wouldn’t fit :frowning:

Its to double the thickness/ cross sectional area of the busbar. On a similar principle as using thicker cables.

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Many thanks to everyone who helped me plan my hifi circuit installation.

In the end I put in 2 radials:

Lapp Olflex Classic 110 CY 10mm sq to Furutech (G) single socket. This cable has a tinned copper braid and PVC outer sheath.

And Belden 83803 (12 AWG) cable to an MS HD Power (G) duplex socket. This cable has (7×20) tinned copper conductors, Teflon insulation, 100% Beldfoil shield with 85% tinned copper braid and a Teflon jacket.

I can switch either of these radials off at the Hagar hifi CU in the room if I want to.

The thin Belden cable had a circuit impedance of 0.08 Ohms and the fat Lapp cable measured 0.04 Ohms.

The Earth loop impedance of the Belden radial was 0.07 Ohms, of the Lapp cable was 0.06 Ohms, and the house ring main was O.41 Ohms.

It may be yet more weeks before I set up the hifi because we have to decide whether to install bookshelves on the rear wall, and I do not want any dust from that work getting into the hifi.

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Well done Jim. As you can never to an AB test, then the answer is “Yes, it sounds so much better. more clear bass, more clarity, better soundstage”

Well, I have ring main sockets near to the audio sockets, so I will be able to compare those.

In fact when I first plug the hifi in I intend to use the ring main for a week or two first.

My advice, don’t do it :smile:

Hey, if it sounds exactly the same, that’s a fascinating experimental result.

I knew that there is a risk of that when I decided to install it.

Looks like a good job Jim.
How have you configured the shields on the cables ???
Remember they need to be an earth/grounded conduit & not part of the earth circuit path as such.
To do this the industry stnd is to connect the shield to earth only at the ‘power in’ end & leave the other end open (unconnected)

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Thanks Mike.

All three shields in the 2 cables are connected to the earth bar in the hifi CU - and are not connected at the socket ends.

Is that what you’re suggesting is best practice?

I think the 3 shields therefore join the same earth path as the 2 earth connectors in the 2 cables (and the unused connector in the Lapp cable, which is connected to the hifi CU earth bar at the CU end and not at the socket end).

Yes JimDog, that’s correct.

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Phew - that’s all ok then. :grinning:

Finally :raised_hands:

Hope the rest of the room goes well. I bet you’re looking forward to getting everything setup again.

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Yes, I can’t wait.

I am listening to a lot of YT music videos lately, and my Qobuz playlists on an iPad when I work out…

When the system comes together it will be quite different, with a new room, improved racks, dedicated radials, new SL2 tweeters, etc.

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I would plug something into the circuits now to start the long burn in process. This will make initial switch on of your kit sound even better on the new mains.

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