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Reid Malenfant
12-11-2010, 19:17
I run a dedicated mains spur from the main fusebox, no consumer unit here as it's kind of old :eyebrows: At the present i'm running 4mm^2 twin & earth over about 20M to get it to the listening room without burying it in walls or floors.

Now this isn't a huge cable but i'll eventually be increasing the cable size a tad due to possible current demand for certain bits of kit ;)

The thing i have been wondering though is if it might be worth screening the new cable against electromagnetic interference? Ok so there will be a couple of feet of exposed cable where it enters the house, travels through the meter & to the fusebox. But prior to this we have the cable feeding the house which is armoured & effectively screened by that armour.

What i'm wondering is if it may well be worth screening the cable from the fusebox right the way through to the listening room & also using fully screened mains cable in the room as much as possible :scratch:

The way i figure it could possibly be done on the cheap (but perfectly effective) is to use aluminium foil wrapped round the cable & obviously earthed near the fusebox..

Any thoughts, other than it'll slightly derate the cable? :eyebrows:

It just occured to me due to this Belkin PF40 having a hefty 4mm^2 screened cable on it's input :)

Mark Grant
12-11-2010, 19:43
The way i figure it could possibly be done on the cheap (but perfectly effective) is to use aluminium foil wrapped round the cable & obviously earthed near the fusebox..


You bodger :lol:

The easy way is steel wire armoured cable also known as SWA

Cheap, screened, sometimes has twisted cores rather than parallel cores which can help.

like this:
http://www.tlc-direct.co.uk/Main_Index/Cable_Index/Armoured_SWA/index.html

probably 3 core 4mm or larger.

You also need these and a box of some kind:

http://www.tlc-direct.co.uk/Main_Index/Cable_Accessories_Index/Glands_SWA/index.html

Mark.

colinB
12-11-2010, 19:50
:lol: Thats yo told.

Reid Malenfant
12-11-2010, 19:56
You bodger :lol:

Mark.
:lolsign: It's a cheap but perfectly sound bodge :eyebrows:

The thing is this. My reasoning suggests that the SWA cable will need to be even larger that the cable i already happen to have at hand, simply because all that plastic & metal covering the cables will allow less heat to escape.

Like all cables they'll be rated according to the way they can get rid of heat due to current draw. I figure a thin layer of aluminium would be better than having to fork out on new ducting to take a 10mm^2 SWA cable. Besides that the bend radius must be humungous on something like that :eek:

As it is i have some 6mm^2 cable rated for trunking & i figure that aluminium being a much better heat radiator & conductor than steel will only lower the cables rating a tad.

It'll still effectively screen the cable to a few hundred MHz & i could probably do the job with less than a single roll of kitchen foil :lol:

Mark Grant
12-11-2010, 20:22
As it is i have some 6mm^2 cable rated for trunking

Is it 'singles' such as this if it is for trunking ?
http://www.tlc-direct.co.uk/Products/CA6SBR.html

You could twist a few singles in the correct colours together and wrap it in foil :)

If you know roughly how many amps you need over the 20 metres I am sure someone can work out what size cable you need.

Remember to always over engineer it with mains for hif use :)

SWA sizes if it helps:
6 mm2 3 core SWA has a diameter of about 17 mm
10mm2 3 core SWA about 20mm, so is not easy to hide.

maybe buy some 6mm2 3 core 'CY' or 'SY' as it is thinner diameter, not as much screening though.

Mark.

Jonboy
12-11-2010, 20:24
Just go the whole hog and do the rest of your house in foil to make sure

http://i419.photobucket.com/albums/pp272/jonboy_01/foilbed.jpg

Reid Malenfant
12-11-2010, 20:34
Is it 'singles' such as this if it is for trunking ?
http://www.tlc-direct.co.uk/Products/CA6SBR.html

You could twist a few singles in the correct colours together and wrap it in foil :)

Mark.
Yep, that's the stuff :) As i say i already have the cable, 100M reels of each ;) Strangely that is what my plans are :eyebrows: Don't worry about someone working it out, i already have - my last job was electronics engineer :)

Just go the whole hog and do the rest of your house in foil to make sure

http://i419.photobucket.com/albums/pp272/jonboy_01/foilbed.jpg
Yes i'd love a faraday cage, i could then pretend to be Brill (Enemy Of The State ;)) :eyebrows: Actually it's a pretty good idea but not very easy to implement :doh: However i know it'd work as where i last worked they kitted out a room for EMI testing & actually used tin foil for the faraday cage. This is how i know it'd be pretty effective :)

Techno Commander
12-11-2010, 22:09
You are all wrong.

Mark, stop bodging. Forget steel armoured, not only will you get a hernia lifting it, but it needs to be used with brass glands at the ends.

You need this (http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0363395). Proper screened cable, but still flexible and easy to manage.

http://img-europe.electrocomponents.com/largeimages/R363367-01.jpg

Reid Malenfant
12-11-2010, 22:17
Any thicker? :scratch: 6mm^2 might do the trick but again it's built into a single cable & as a consequence won't carry as much current as seperated conductors that can give up heat better.

The idea is sound though :) :doh: Ooohh, bad pun :eyebrows:

Techno Commander
12-11-2010, 22:23
I know you can get up to 6mm sq braided mains, I used to make plenty of leads using thar stuff in a previous job. The 6mm stuff is rated in excess of 40 amps. How many Krells do you want to hang on the end of it?:)

Dont forget you need to be able to fit it in your fusr box.:lol:

John
13-11-2010, 06:54
Mark I would of thought 10mm would be best for you as you got some big gear

Mark Grant
13-11-2010, 12:12
Does this cable have to fit inside some existing pipe/ducting etc?

You could buy 6mm2 or 10mm2 x 3 core SY, nearly as large as armoured cable though and not as well screened.


If going down the DIY route of twisting some cables together, I would put two or more earth wires in the bundle, acts a screen when twisted together with the cores and also reduces the earth resistance.

Mark.

Welder
13-11-2010, 13:55
Make I larf :D
If you have a look in the last picture in my Gallery pics you can see one way to make a mains cable to carry plenty of current. I used to have this stuff running from a dedicated mains outlet with a separate ground in the days when I had valve amps and moar kit!
Did it make any difference? Nope, not one bit, but fun to make none the less.
I daren’t ask what your going to use to draw the kind of current 2mm x 2 core will take; sounds like a fire risk in the making.
Just twisting the cores is usually quite sufficient to reject noise.
I can’t quite work out why people are paying serious money for cables when they are pretty easy and cheap to make yourself.
The stuff in the pic is 1.5mm core twisted pairs, mylar foil and copper braided screen x3 twisted together.
Lotsa “core!” factor but sonically…………………well, it’s your money ;)

MCRU
19-11-2010, 21:33
Hi Guys,
I get a lot of people asking for cables for a dedicated mains supply, belden 83803 gets chosen quite often for shorter runs and it has good feedback from my customers who have used it.

Reid Malenfant
19-11-2010, 21:43
Umm, reminded me of this thread :eyebrows:

I have 6mm^2 individual mains cables which are designed for use in trunking. They are solid core, each is insulated with a pretty blue, brown & green/yellow cover :eyebrows:

Looking at the thing i may well be able to install two loads of 6mm^2 Live & Neutral cables, there really isn't a shed load of need for the same with the "earth" cable is there... It's just for fault purposes & the chances of everything going wrong at the very same time must be vastly more than winning the lottery ;)

30Amp+ of earth still takes the mickey imo :eyebrows:

Jac Hawk
20-11-2010, 23:10
would it not be easier to add up the total amps, then split it into 2 or three smaller circuits, then you wouldn't have the headache of using large diameter cable that will be difficult to hide and terminate, also if you are going to go to that much trouble why not use shielded trunking.... just a thought

MCRU
21-11-2010, 14:13
I agree, a lot of modern equipment does not draw as much current as in the old days because of the environment and green issues, if you have 10 or 12 boxes then maybe 40 amp cable would be needed but not if you have say amp, cd, turntable and speakers so you could get away with a standard hi-fi mains lead type cable.

Reid Malenfant
21-11-2010, 14:39
would it not be easier to add up the total amps, then split it into 2 or three smaller circuits, then you wouldn't have the headache of using large diameter cable that will be difficult to hide and terminate, also if you are going to go to that much trouble why not use shielded trunking.... just a thought
But i already have the cable & the trunking is already in place & doing a grand job of hiding the cable that's already there ;) I have equipment here to terminate cables of up to 25mm^2 so 6mm^2 is not a problem at all :eyebrows:

I agree, a lot of modern equipment does not draw as much current as in the old days because of the environment and green issues, if you have 10 or 12 boxes then maybe 40 amp cable would be needed but not if you have say amp, cd, turntable and speakers so you could get away with a standard hi-fi mains lead type cable.
What's this "green" thing i keep hearing about :scratch:

Add up the current drawn by a Mackie M3000 (bass) feeding 2 channels @ 2ohms, a Krell KSA250 (centre speaker) driving 2 channels @ 4ohms & a Parasound HCA1206 (lower mid, mid, treble) driving 4 channels @ 4ohms & 2 @ 8ohms & you'll soon realise these can draw a fair old bit of current :eek: Not forgetting another pair of power amps to drive the rear speakers :doh:

So one or two boxes more than normal i'd say :lol:

Jac Hawk
21-11-2010, 15:55
But i already have the cable & the trunking is already in place & doing a grand job of hiding the cable that's already there ;) I have equipment here to terminate cables of up to 25mm^2 so 6mm^2 is not a problem at all :eyebrows:

What's this "green" thing i keep hearing about :scratch:

Add up the current drawn by a Mackie M3000 (bass) feeding 2 channels @ 2ohms, a Krell KSA250 (centre speaker) driving 2 channels @ 4ohms & a Parasound HCA1206 (lower mid, mid, treble) driving 4 channels @ 4ohms & 2 @ 8ohms & you'll soon realise these can draw a fair old bit of current :eek: Not forgetting another pair of power amps to drive the rear speakers :doh:

So one or two boxes more than normal i'd say :lol:

Ok so run 2 circuits, then you are sure, BTW is everything else in this room of yours shielded, if not, then this whole exercise would be a waste of time:scratch:

bose.ltd
21-11-2010, 17:44
the current is on the secondary winding of your transformers, thats their job have you seen how thin the primary wire is on a mains transformer. These massive mains cables are a joke. imo

Reid Malenfant
21-11-2010, 17:45
I wouldn't be so sure about that ;) Equipment that i have connected to a certain mains filter definately gives better results & yet the mains leads from the filter to the equipment aren't shielded. The mains lead to the filter itself is shielded though :cool:

I'm sure a pretty good percentage of it could be screened as well though :)

Who was it on TV that said "every little helps" :scratch: :lol:

goraman
21-11-2010, 17:53
I thought I'd make a little wireing joke.
http://www.lucas.co.uk/
The joke is there website seems to be down...
Much like the wireing in my 79 Triumph.
Mabey the wireing to there server has a problem.

http://www.mez.co.uk/lucas.html This is funny!

I'll bet you guys could tell a few storys too.

Reid Malenfant
21-11-2010, 17:57
the current is on the secondary winding of your transformers, thats their job have you seen how thin the primary wire is on a mains transformer. These massive mains cables are a joke. imo
Perhaps you don't understand about efficiency & current draw?

Perhaps you don't understand about the importance of having as low an electrical impedance as possible feeding a big power amplifier :scratch:

Please do some reeding up on certain kit before jumping to conclusions :) For instance, the Krell KSA250 uses a 4.5KVA mains transformer & that's just one amplifier :eyebrows: It should only be run on a dedicated 20Amp mains spur, again - just that amp!

So all of a sudden what looks to be "a joke" turns out to be a necessity :rolleyes:

goraman
21-11-2010, 18:19
To small of a mains cable will kill a Pioneer Spec2,Krell or Pass Labs or the big Sansui's like the BA5000 as the amp just cooks to death struggling with reduced current.
Volts x amps = watts,if the amprage is reduced (current) the voltage must rise to produce the same number of watts and when it cant,you have turned your amp into a hot plate.Killing it prematurly.
This is how it was explained to me.

Reid Malenfant
21-11-2010, 18:29
http://www.mez.co.uk/lucas.html This is funny!

I'll bet you guys could tell a few storys too.
:lolsign: Cracking link :)

I remember a pair of pliers vapourising in front of my eyes before i was temporarily blinded by the light given off by them. I was holding them at the time :doh:

:mental: I still have the pliers & they now have a big chuck of steel melted out of them, vapourised in an instant :eyebrows:

Ali Tait
21-11-2010, 18:33
Yep,same thing has happened to me before. Bit annoying when it's a good pair of side cutters!

Glen B
21-11-2010, 18:44
I agree, a lot of modern equipment does not draw as much current as in the old days because of the environment and green issues, if you have 10 or 12 boxes then maybe 40 amp cable would be needed but not if you have say amp, cd, turntable and speakers so you could get away with a standard hi-fi mains lead type cable.

Hmm, that's interesting. Electronic equipment mains cable for wiring installation ? That would not fly in North America. Surely you guys must have some kind of electrical codes in the UK ? National electrical codes in the United States and Canada are very specific about the types of wire/cable to be employed in electrical installations. Some individual major American cities have their own local codes that are even more restrictive than the national code.

In Chicago and New York City for example, non-metallic cable and outlet boxes are not permitted. Chicago requires rigid conduit only, except where new wiring must be installed in existing construction, in which case, flexible armored cable is allowed. In North America, the use of a non-approved type of wire like appliance power cord for a branch circuit (what you call a mains spur) would constitute a major code violation and fire hazard. If you were to have a fire that was caused by your inappropriate wire, that would be grounds for your insurance company to deny payout on a claim.

Cheers :)

Glen

Marco
21-11-2010, 18:44
the current is on the secondary winding of your transformers, thats their job have you seen how thin the primary wire is on a mains transformer. These massive mains cables are a joke. imo


Hi 'bose.ltd',

Welcome to AoS :)

Could you please pop into the Welcome area and introduce yourself to our community, by providing your real first name and basic location, system details and music tastes, as this is the required procedure for new members joining AoS.

Cheers! :cool:

Marco.

Reid Malenfant
21-11-2010, 19:01
Hmm, that's interesting. Electronic equipment mains cable for wiring installation ? That would not fly in North America. Surely you guys must have some kind of electrical codes in the UK ? National electrical codes in the United States and Canada are very specific about the types of wire/cable to be employed in electrical installations. Some individual major American cities have their own local codes that are even more restrictive than the national code.

In Chicago and New York City for example, non-metallic cable and outlet boxes are not permitted. Chicago requires rigid conduit only, except where new wiring must be installed in existing construction, in which case, flexible armored cable is allowed. In North America, the use of a non-approved type of wire like appliance power cord for a branch circuit (what you call a mains spur) would constitute a major code violation and fire hazard. If you were to have a fire that was caused by your inappropriate wire, that would be grounds for your insurance company to deny payout on a claim.

Cheers :)

Glen
Hi Glen, yes we do have wiring codes etc in the UK :) In fact in certain areas of houses over here you have to be qualified to do any wiring work at all, this would include kitchens & bathrooms. If the house owner did the work & wasn't qualified then obviously the insurance company would take a dim view of it & refuse to pay out if it was proven to be a wiring fault caused by whoever did it caused a fire etc.

Jonboy
21-11-2010, 19:25
Perhaps you don't understand about efficiency & current draw?

Perhaps you don't understand about the importance of having as low an electrical impedance as possible feeding a big power amplifier :scratch:

Please do some reeding up on certain kit before jumping to conclusions :) For instance, the Krell KSA250 uses a 4.5KVA mains transformer & that's just one amplifier :eyebrows: It should only be run on a dedicated 20Amp mains spur, again - just that amp!

So all of a sudden what looks to be "a joke" turns out to be a necessity :rolleyes:


A dealer friend of mine used Krells with Apogee Divas on the ends of them in the past, he had to have a 100 amp supply put into his house to get enough current to make them sound and run how they should, it involved having the road dug up and new cables layed into the house

Jac Hawk
21-11-2010, 19:30
if you do the wiring yourself as long as it meets iee 17th edition and it is verified by an electrician who holds a qualification in the 17th edition you are ok

Reid Malenfant
21-11-2010, 19:31
A dealer friend of mine used Krells with Apogee Divas on the ends of them in the past, he had to have a 100 amp supply put into his house to get enough current to make them sound and run how they should, it involved having the road dug up and new cables layed into the house
:lolsign: Now that may be going a little far, but you did say Krells plural :eyebrows: It can't be underestimated how much the mains power supply impedance affects these things, the lower the better even if you aren't going to draw all the current that the wiring suggests you might ;)

PS Jon, pmsl @ your avatar :eyebrows:

Reid Malenfant
21-11-2010, 19:35
if you do the wiring yourself as long as it meets iee 17th edition and it is verified by an electrician who holds a qualification in the 17th edition you are ok
Don't worry about that Mike, where my health & safety are concerned i go above & beyond the call of duty :eyebrows: Everything will be wired, insulated & terminated to above any specs out there ;)

SimontY
28-11-2010, 13:38
There seem to be some very random opinions posted here! Obviously, even this system will run just fine on some thin mains cable but this is about upgrading, not barely working without it all setting on fire. The thicker the cable is, the better, simple as that. Shielding will be a waste of time, it almost certainly won't make it sound better. Just think, good mains cables we use on our gear are not shielded, only the basic ones just a bit better than standard kettle leads are shielded. Top end ones are usually unshielded, because it's deemed to sound better. Just like top end interconnects are usually unshielded!

My advice would be to use the biggest ring main cable you can practically fit, and install it in a ring, not a single spur.

The story of a 100A supply coming in is brilliant but, to be fair, he obviously had some old/basic wiring there as 100A+ to the consumer unit seems to be the norm in houses where I've looked.