Mains

looks like i'm finally getting around to fitting the fused spur back to the D.board for my stereo

current plan is a to use a single run of 6mm twin and earth to a decent 2/3 gang wall socket/cooker box. It'll have to be to terminate 6mm cable! ( this is crazy hifi nonsense i'm sure

Any advice/experience out there i should learn from.

john

 

Electricity hurts. Never ever be tempted to work on a live circuit.

Dunno really. Is there anything you can spray the connections with so that they don't oxidise?

If it's going below floorboards, make sure it's in a conduit so that it's creature-proof.

There may be more. I'm not an electrician

 

Na, use to work live all the time

DeOxit/Pro Gold or simmilar

Not neccessary, conduit is very rarely used in domestic instalations. It is enough to clip the bare T&E to joists etc.

You may be able to terminate the incoming 6mm cable to a junction box and take 2 more from there, tho it would be a squeeze.
I think you should be able to terminate a 6mm cable to a decent socket with some carfull twiddleing. Just dont be temtped to start cutting some of the strands off to make it fit.

Not sure what use a cooker outlet would be??

 

forget the T+E use 4mm swa into MK metal clad sockets,dont bother with 3 gang sockets,there limited to 13A,and as has already been mentioned if in doubt dont.

 

Hi,

Use solid core cable, make sure the cable is "armoured", that is shielded by a set of steel wires with practically 100% coverage which operates as both RF and EMI shield when earthed back at the fuse box. Alternativeily use copper piping to run the cable through, again earthed.

Consider breaking out a substantial number of single outlets using star wiring for L, N & PEN from that, ideally with wiring to the armoured or in copper piping.

Make sure to use a junction box for termination in which you can include RF & AF bypassing using suitably safety rated capacitors to achieve the following aims:

1) Make sure the inductive component of the mains system is compensated.

That requires an RC series circuit with a capacitor rated for across mains use, that is X1/2 rating and of large value in series with a suitable resistor. It may be most prudent to actually measure the actual 50Hz impedance of the mains (which includes substation etc), but if that cannot be done use 1R, power line impedance increases above around 1KHz and thus the capacitance used cannot really be judged too large, around 160uF appear ideal, HOWEVER I am not aware of readily available X1/2 rated capacitors above 2.2uF.

A possible solution is to fit a 2.2uF X1 or X2 rated capacitor directly across the live & neutral in each outlett and using series resistors of 1R * number of available outletts (plus any added RC combos in the actual junction box.

Also be aware that the blind current through the capacitors will keep the electricity meter spinning even with no load. Depending on how you use the system it may be worth adding a main powerswitch/breaker for a central system shutdown that would also disconnect all the capacitive bypassing.

2) Make sure that neutral and earth are linked at least for RF frequencies, preferably down to a considerable level of audio frequencies.

This requires large value Y1/2 rated capacitors, definitly in the junctionbox, adding some in the outletts is a good idea too.

3) Use high quality, shielded and low inductance mains cables of IDENTICAL LENGTH for all gear.

If gear has fixed mainscables cut them off and fit IEC cable plugs, for gear using a figure 8 mains connector use an IEC to Figure 8 adapter.

A good choice of mains cable are fully filtered and ferrite packed Eupen mains cables, these are quite affordable generic items and obviously compliant with all electrical safety requirements and include depending on type various types of filtering, worth getting a few of each type and try which works best where, but make sure that you get the ferrite packed conductor version.

Ideally you would use shieldedsolid core mains cable, but that is not permissable under UK electrical code, so I cannot recommend the use of such cables to others (even though I use them for my own system).

Anyway, if you have semi-decent mains at all in your area (I have at home but at works it's so bad our computers die like flies and we are getting the whole floor put on a mains regenerator/ups combo) the above should get a major boost in sound quality.

Ciao T

 

Hi,

Before I forget, consider really giving all the hardware (junction box contacts, socket contacts etc) the brasso treatments and consider trying to apply some contact preservatives to all exposed metal parts so they cannot rot away....

Ciao T

 

I'll second that !!

 

3d and all

thanks very much - i think i follow most that!

so the idea is

use 4mm swa cable ( should also help with the rat situaton!) solid core not stranded - though this doesn't comply. I asume that's not a huge issue

take the SWA radial into a JB (i'll get my electrician friend or an engineer at workto put this together with the caps etc) local to the hifi. star from here to as many outlets as i can afford/need and use the MK metal ones.

get some decent mains leads - are you sure about all the same length?
have i got this right? btw any chance of quick sketch of the cap and R circuit?

thanks everyone
John

 

Can I just add as a footnote to 3d's post:

1) This works well, but I'd suggest different values. More on this here:
http://www.acoustica.org.uk/other/mains_Z.html
http://www.acoustica.org.uk/other/filter.html

I couldn't recommend the 160uF even if you could find it, that's 12.8A of reactive current, and 130W dispiated in the 1W resistor...

2) May work well, but be careful with the values of the cap. Earth leakage in equipment is capped at 3.5mA or 7 mA depending on class, this means a Y cap of 47nF is about the limit. Much bigger and your RCD will keep tripping out.

 

Back from the dead for one post only

Be warned. Any work must be certified by a proffesional electrician. It's annoying but the public are no longer trusted to carry out their own electrical work

If you want lots of infomation about spurs and the like I've got all the stuff collated by RKR. All the knowledge from a basic single spur all the way upto wiring your house using seperated single strands for every conceivable box. Email me if you want the info.

FWIW I'd use 10mm2 T&E with as few junctions as you can get away with.