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Mains spurs

RichardH

RichardH

Bodging pleb
Been thinking I ought to do this, particularly as we have a fridge/freezer on the same circuit as the hifi :(

It's slightly complicated, as the room with the hifi in is a long way away from the meter. In facr, we have a run of armoured cable that goes half way there, which is on a single large ampage micro circuit breaker. This then feeds a secondary fuse board (though it's all MCBs again). I'd have to run the separate spur from this point. Even then, I'll probably have to run armoured cable round the outside of the house, as this part is single storey, with no access to parts of the roofspace.

So, questions:

  • Will this still be worthwhile (I'm sure it will)?
  • Anything I can do re earthing, or should I just rely on the earth feed that comes into the secondary fuse board?
  • I have a spare positon in the secondary fuse board, and assume I'll use another MCB - rating?
  • Recommendations for cable to use in this situation? How flexible will it be - I need to get round corners...
 
tbh mate, theres a lot of question you have asked and a lot of answers required, my suggestion would be for you to get an electrician to do the job
one word of warning, i have seen some very bad practice promoted on hifi spurs, in particular the use of seperate earth spikes for the hifi spur, this can be very dangerous and creat a potential difference between the earth spike and the existing house earth circuit. in short it means the could be a potential voltage between caseing of audio components and and other metal objects in the house.
 
Hence my query re earths - I'm already aware of the issues with earth spikes, and was already sure I wasn't going to do that.

Frankly, I'm fully capable of doing the job myself - I did rewire half the house myself, after all. My queries were more to do with any top tips others who have done the job before may have - recommnedations for particular cable, MCBs etc, and also any comments about whether the set up I have will mean the benefits are negated.

It may well be I get an electrician to come in and terminate properly at the fuse board, but I'd prefer to be the one who chose the routing of the cable, what cable it was etc.
 
Hi Richard
sorry i wasnt trying to say you arent capable, my bad way with words i guess.
As for cable i would say SWA, but what CSA i would think is ultimately up to you. As people seem to think that the greater the CSA the greater the sonic improvement ( i would hate to try and terminate 10mm2 into a socket)
 
Sorry - I probably mis-replied too - I was trying to say that I intended my queries to be more hardware related - whether I do it myself or I get a tame sparks to do it is the next step....

Well, just having a look, I can get 50m of 4mm 3 core for £75, or 6mm for £92. I'll need at least 25-30m, so a shorter length isn't worth poking around for. Looks like any garden lights I do in the further will be slightly over specified in the cable department....
 
I asked RKR over on the Naim forum; he kindly sent me loadsa info on mains spurs. If you ask, I'm sure he'll respond. Might give you some ideas, even if you don't follow all his recommendations.

Myself, I have two separate spurs for the audio, of which only one is in use. Done with 2x10mm² wires and a separate 10mm² wire all the way down to the main house earth pint, i.e., not through the meter (less resistance/impedance). Gave a worthwhile improvement over the old electrics I had before.
 
Funny, I was just wondering whether to go for 2 core cable, and run the earth as a separate cable. I'll pop over to The Other Place....

Even if I lose all the pops and thunks from the other appliances switching, it'll be worth it....
 
Let me add that I had my install done long before I ever heard of the Naim forum and RKR. It has some similarities but also differences, some of them to do with differences in safety regulations between Germany and UK.
 
im an electrician and have done new mains circuits for hifi shops

(btw they are not spurs - even though people including naim call tehm that - a spur is off an exsisting circuit - what you want is a new dedicated circuit)

for hifi you want to create a very low elz however the cable length affects this plus you will get voltage drop over a certian lenght

you can run a secondary cpc to reduced the elz - however a lot of this depends on many factors including the your incoming earthing arrangements, the sizing on your main and equipotential bonding conductors etc

also you cant get 10mm2 casble into normal socket outlets

leave spikes alone! unless you know what you are doing and have the relevant test gear - i was at recording studio recently that had a spike connected to a mutiway by some 4mm2 cable - good job ther wasnt a fault!
 
what differences between german and uk standards

bs7671 has been harmonised with euporean standards
 
depending on cable run length:

6mm2 twin and earth pirelli cable
a secondary 100mm2 earth cpc

mk unswitched sockets
mk circuit breakers

make sure that :

1 you have a pme connection from your supplier
2 that the main bonding connectors are 16mm2
3 that the secondary bonding connectors are 10mm2 and are cross bonded between the incoming water and gas suppplies

dont go for armoured cable - expect if you have to run undergroud - there is no reason for it

the main sonic improvement are to be gained by the good connections and a low elz
 
Mike - thanks for the comments - you say don't go for armoured cable - even if the cable run is outside the house? (though I would run it under the eaves for some protection/hiding anyway). I guess the other route would be to run conduit for it to pass through.
 
i wouldnt go for armoured in your situation - unless you want to bury the cable - then you will nedd to dig a trench , line with sand cover the cable with warning tape and tiles etc etc - then there is terminating the cable etc etc

its probably eaier to use plastic conduit and draw through some 6mm2 singles - you dont have to use twin and earth because the outer protection is provided by the conduit
 
Originally posted by mikeb
what differences between german and uk standards

bs7671 has been harmonised with euporean standards
Click to expand...
The Germans have less fuses. I'll never understand the UK obsession with fusing the fused fuse.
 
Hi Richard ,
this might not be what you are after, but it might give you a few idea's think about or adapt for your own purposes. If you are running cable underground or outside the walls of your house then i reckon that SWA cable is where you should be at. If you have ever read the Ben Duncan 'Super Spur' article, which i first saw in HFN&RR a few years ago, he recommends using SWA cable, with a seperate CPC/Earth wire. Even though i took a lot of care and attention to detail when fitting my spur,it didn't totally eradicate all clicks and pops on my mains, although it did reduce them. Moving on to my Mk 2 version , which involved the use of an active electronic filter network killed them dead. The famous 'sat upon' sound was never noticed by me but the lack of loud 'rifle shots' from my speakers , when the volume was up high and the central heating was on were. 'Sat upon' i can live with, 'rifle shots' i can not .
Sids spur
HTH.
 
mikeb, apologies for my ignorance, but what do the abbreviations:

cpc

elz

stand for? (i may have left out others) i sort of guess the last "z" indicates impedance, but dont know.

enjoy

ken
 
Originally posted by mikeb
also you cant get 10mm2 casble into normal socket outlets
Click to expand...



Mike,

I had no problems with this in my installation, but it was just a single run of cable to a single socket (MK, IIRC).

Do you mean that you can't get two 10sq.mm cables into a socket outlet?

cheers, Martin
 
ok
cpc = circuit protective conductor - usually the earth wire in twin and earth

can be the sheath in mineral insulated or armoured cables


elz = earth loop impededance - measured in ohms


low elz can acchevied by a larger cpc or more cpcs


into sockets mk sockets are 2 x 6mm , 2 x 4mm or 3 x 2.5mm
so yes you could get 1 x 10mm into an mk - other brands have poorer quailty terminals so i wouldnt want to put more than 2 x 4mm in them
 
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