Dedicated mains electrical supply - electrician installed wrong cable - should I start over?

I use a 2.5mm dedicated ring and it is fine with my system.

I'd try it and hear for yourself before ripping it all out. The dedicated circuit removes a lot of injected noise from other household items. The idea of lower resistance wiring may offer some advantages, but I've never felt upset by the superb results I get.

DB.

Although I don't currently use a seperate spur from my consumer board for my audio stuff.. alough its on the list... I would have thought seperacy over conductor diameter would have the greatest benefit unless you have very long lines back to the consumer board.

Simon

I use radial circuits rather than a ring circuit, but I found the jump from 2.5mm to 6mm was huge in terms of sound quality. I now use 10mm and the jump was just as big. I personally would ask for the larger cables as first requested.

Simon,

A separate spur from your consumer unit has no great advantage over using any other circuit on the home supply (been there and done that). It's best to have your dedicated supply, ring or radial, taken from the tails before the HCU, with it's own consumer unit and breakers. With a spur from the home CU you still get all the interference from appliances, computers, light switches, hairdryers (although it doesn't look like you need one ) etc and in John N's case, toothbrush chargers. It's quite surprising the effect that SMPS's have on sound quality and so easy to demonstrate once you have a separate dedicated supply.

I use dedicated 6mm radials to six sockets and a separate earthing rod in the garden, which gives me something else to water in the summer. I was lucky to find an electrician who had worked in recording studios and wasn't too skeptical of the requested specs.

ATB

Steve

my own experience is somewhat mixed, but still in favour of a single radial 10mm sq circuit for the hifi.

the reason i say "mixed" is that, in the context of a active the system, such a setup results in a highly tuned system that o me sounds out of this world, but is ruthlessly revealing of all sorts of installation issues -- some of which one wouldnt have thought mattered that much. the other side of the coin is that now i have gotten used to this highly tuned SQ -- i have also become very sensitive to any changes in it.

but i have learnt a LOT about what makes my system tick over time -- and i believe i have managed to achieve some stability in performance -- and its frighteningly good, even at this 552 level.

i dont know what to advise the OP. if it were me -- i would take the view "suffer once and enjoy forever" and get the optimal circuit installed -- taking into account what Steve said about real 'dedicated' circuit.

Good luck and...

enjoy

ken

Hi duckwarp,

Here's the good news:

1) 2.5mm and 4mm are so close you won't hear a difference.

2) the second time you pull up carpet & floorboards they come up much more easily

and the bad news:

1) You should have spec'd 6mm or 10mm rather than 4mm in the first place

The suggested compromise solution that allows face saving all round:

1) Ask the guy to start over, but use 10mm (or 6mm) instead of 4mm

2) share (halve) the additional cost because you have now changed your mind (i.e. spec) but he got it wrong originally - you should be able to negotiate an additional price that you're both comfortable with (note - 'comfortable', not 'happy') 

Remember, poo happens but life is too short to do things by halves and there's plenty of folk on the forum who swear by a dedicated mains of 'decent' spec (6 or 10mm) - personally I use a 6mm spur and then daisy chain 6 double sockets with 2.5mm off the spur (because you can't get 2x6mm into a Crabtree socket). 

...and think of how good it's going to be when it's all completed & running off its own decent spec spur

I'm with Steve on this, although I went with 10mm. The cost was "modest" but the result was anything but and well worth the effort.

Thanks for all of your replies.    Looks like the consensus is to start over.  The sound improvement from the 2.5mm is apparent but it is not massively improved.  Also when I first turned the units on the NAP250 power amp caused the fuse switch to trip.  Seems stable once on but getting it on took a few attempts. That can't be good.  This never happened when it was on the standard house ring so I am wondering if some installation issue is the cause anyway.  Perhaps a good excuse to start over!

Hello duckworp,

Your fuse-trip maybe caused by the electrician using a fuse in the consumer unit [a.k.a. fuse box] that's too small for the job.

A fuse size of 32A is fine, or even a 40A will do nicely.

Having to use the main household consumer unit is okay if the dedicated audio circuit uses a fuse on the unprotected side of the dreaded RCDs. The unprotected side usually has a couple of fuse positions available that are usually reserved for circuits like security alarms, or freezers, which you don't want to involved in a power-cutout in the event of a RCD tripping; basically an RCD is a trip that cuts out a bank of individual fuses, so if your audio fuse is on the unprotected side it's getting power directly from the meter tails, and won't trip out with a group of fuses every time a bulb blows on a lighting circuit, or some other minor issue on a completely different circuit to the audio.

RCDs are technically a good idea for household safety, but they can degrade the sound quality of audio if they are 'protecting' a fuse that is used for dedicated audio, so RCD protection isn't desirable for a dedicated audio circuit.

Consensus of opinions suggest 6mm cable is very good and adequate, but 10mm cable better and excellent.

However, the 6mm does have the advantage of easier fitting, and ability to 'daisy chain' one socket to another.

How old is your household consumer unit [fuse box] ?

How far is it from your meter?

Debs

I always thought the fuse rating had to less than the current carrying capacity of the cable.

I doubt 2.5mm cable will even carry 32A.

fatcat,

read the whole post... especially the bit about 6mm cable good, 10mm excellent 

Debs

2.5mm cable in a wall/conduit installation is rated at 20 amps

However the OP's circuit is a 2.5mm ring & that is rated at 32 amps.  

The electrician I found happened to be a lapsed 'audiofool' and so was intrigued when I spec'd 10mm.

He was keen to hear the 'before & after' and so we had a short listening session after his tussle wiring in such an unwieldy cable.

Damned if either of us noticed any difference. Less fluctuations though.

G

I didn't see that: fitting a ring no so good for the dedicated audio circuit : (

Need a radial circuit - 6mm or 10mm, 32A or 40A fuse - not with a group of fuses on an RCD.

Debs

no i didn't. 

i said it maybe, because it maybe.

we don't know what size the fuse it do we?

Also, duckworp uses a qualified electrician, who would be needed to replace a fuse that is too small, and he wouldn't be daft enough go to a 32A or 40A fuse with little 2.5 cable.

My advise remains clear, don't use 2.5 cable, go to 6mm or 10mm, and get a bigger fuse : D

Debs

I noticed you did not say "teethbrush."

I'd be on the phone chewing them out until they rip it out and fix it.  It sounds like it does not even *work* properly much less help you out.  Tell them you afraid to fall asleep listening to your system because the new wiring mess might burn the house down.

Steve, thanks for you reply.. Well I have a different set up to most here  that works well and gave a very worthwhile improvement.

My mains improvement came from

• new CU right by master fuse/meter with a low impedance bus. (certified)
• New TT earth in place of PME earth (certified)
• Fused 5m dedicated RFI rejection braided mains cable (of many small diameter copper cables) feeding audio equipment distribution box. This tail taken from the ground floor inside ring circuit.  (DIY)

Simon