To make it crystal clear

Naim are not allowed to give advice on this topic.

I have already tried them.

Regards

Mick

Vuk's page

for the definitive reply. Although it does have a US bias on re-reading.

cheers

Nigel

1. "6 mm" cable should be fine (as this is the guage used in the majority of uk cooker outlets).

Try,if poss,to install on its own board,or as close to the incoming supply as possible)

"10 mm" would possibly be slightly better(weather the gains in performance is worth the extra,I do not know),but would be quite a bit more expensive and would be an absolute sod for the electrician to work with in routing and terminating into the back of your wall socket.

2. Unswitched MK or Crabtree socket would be appropriate (without neon indicator lights etc)

3. If you do decide to go for a double socket,I would suggest using the left hand connection for the "mission critical" kit.

4. I remember having a conversation with Andy H. (a fully qualified electrician) on a similar subject,and I remember he was aghast at the suggestion of only one rod being used suggesting 3 or 4 connected rods would be a more appropriate number to correctly earth.

To be quite honest,I don't believe he was in favour of putting a seperate earth spike in (possibly something to do with the legal regulations ?)

Regards

Chris

Has anyone tried connecting the 'supplied' earth to a rod and then running from the rod to the hifi. Should give increased earth stability whilst allowing for a large current on the earth, there's got to be some legisaltion against this!

Matthew

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"10 mm" would possibly be slightly better(weather the gains in performance is worth the extra,I do not know),but would be quite a bit more expensive and would be an absolute sod for the electrician to work with in routing and terminating into the back of your wall socket.

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I think 10mm.sq would have been ok to fit into the unswitched MK socket I installed last night - however, I imagine I'd have had to have done some serious compression of the strands - or, cut two or three off. I used 6mm.sq (8m of) and it's sounding great. No special earthing, 30A cartridge fuse.

quote:

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3. If you do decide to go for a double socket,I would suggest using the left hand connection for the "mission critical" kit.

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Why?

John

PS. Mick, it really is worth doing. I'm only wishing I'd done it sooner!

I came accross this one purely after a series of very anorakish sunday morning experiments.

I have no scientific evidence to support this theory,but if you look on the back of a typical MK socket(I just happen to have one right in front of me as we speak).The mains "live" enters through a connection that is quite a bit closer to the left hand (now viewing from front) connection than to the right.

It must be said that the actual improvement is very very small and subtle,yet it is deffinatley there ! (It took me a couple of times to "home in" on the difference).

(anyway,it costs absolutly nothing to try,so why not?)...(remember..we are talking subtle here !)

Mick,as with John,I personally found the improvemets to be worth the effort.

Regards

Chris

if you don't have a spare circuit in your existing fuse box your Leccy will need to replace it, or split your incoming supply and install a second box. Both of these are likely to be expensive (e.g. £100+ for a new box + time to fit it).

Naim have always maintained that a spur is better, but Russ Andrews reckons that you're best to install a 'ring' instead. The ring has two runs of wire from fusebox to socket. E.G.:-

Ring:- FB=====S

Spur:- FB-----S

Russ also offers special cables for wiring up your earth spike & the main ring/spur, as do one of the hifi mags (HiFi News?)

If you decide to use 10mm.sq cables (45A rated) you cannot wire up a ring, as you can't jam two wires into the appropriate holes.

If you use standard cables you will find they are directional, like any other wire. The problem is listening to the wire both ways round without your electrician ruining the mood by laughing hysterically.

I'm sure I've read that the MK Logic sockets are good, even though they are switched.

The standard way to fit an earth rod is to connect it to the back of the socket. The mains earth wire must still run inside the cabling from the fuse box to the socket for safety reasons, but is terminated without connecting to the socket.

For this to be safe you *must* have an RCD in the circuit at the fuse box.

If a fault occurs, the full current in the mains will be sent through to your earth rod. If the rod has a bad connection to the earth then insufficient current will flow to allow the fuse to blow. If the rod is OK, but the wire to it is under-specified, it could fail before the fuse blows. Now you have a fault and no earth (and maybe a fire, too)!

The RCD will blow very quickly, as long as the rod will pass a tiny fraction of one amp of current. The Mem A100HE (about £75 from an electrical wholesaler) is recommended by Russ Andrews, as it uses better specified components internally. If you also need a new fusebox, you can get a Mem one with this RCD installed internally.

An alternative configuration has been suggested to me. It might be safe to install an earth rod & attach it into the common earth circuit at the fuse box. In this way the rod will improve the system performance, but the mains earth will save you in case of a fault.

I intend to try this myself, but I'm aware of three possible problems with this configuration:-

1) The multiple earth connections to the fuse box could give me an earth loop.

2) If there's a potential difference between my earth and that from the sub-station, DC (or AC?) would flow from the mains into my spike. At least this can be easily checked.

3) If my earth is better than that from the sub-station any house on my street could earth into my spike. Better make sure those connections are really well set up.

John,

one set of 10mm.sq cables will definately go into the holes on an MK socket - tried it last night!

cheers, Martin

[This message was edited by Martin Payne on THURSDAY 26 April 2001 at 01:05.]

[This message was edited by Martin Payne on THURSDAY 26 April 2001 at 01:20.]

Armed with all the information above (very good info at that).

Golden question is...Have you now drawn up a plan ?

Please keep us informed .

Regards

Chris

Thanks for the information, everything is much clearer now. This prove that a very old saying is true.....everything is easy when you know how.

The mystique of the subject is gone and I am even tempted to do most of the work myself and leave the final connecting of the cable to the mains in the hands an electrician.

Fortunately I am lucky that routing the cable from mains box to near the Hifi is a fairly simple task and the cost of cable and ancillaries is fairly modest, so yes I intend to give it a go.

I have a sparky coming around next week to take a look and I will take it from there.

The ground eathing looks a little more problematical for a very silly reason, I had my garden revamped 3 years ago and have had a maintenance free patio style laid down with minimal amount of soil left.

One last awkward question....Has anyone installed ground earthing AFTER installing a dedicated spur and was there any significant improvement. It seems to me (correct me if I am wrong)that the bulk of the improvement comes from installing the dedicated spur and that the earthing is more icing on the cake.

Anyway once again thanks for the information...it was all good stuff.

Regards

Mick

Just make sure the front baffle of your SBL's are set slightly forward of the fireplace. I have exactly the same problem as you and of course no fireplace would be better but this is the real world.

regards

Dev

Is copper the best conductor available?...No.
Is copper a rust-free metal?...No.

Have you considered what happens to a piece of shiny copper when it's been in moist earth for a while? Just look at the coins in your pocket.

I'd say the best material for the job is gold. It conducts really well and doesn't rust.

BAM

Buy gold rods.........I am but a humble Public Servant.

Regards

Mick

p.s. ...this is one area where I am NOT advocating the Non Ferrous approach

Regards

Chris

you MUST NOT USE 6sq.mm CABLE WITH A 45 AMP FUSE.

6sq.mm cable is rated at 30 amps - you must use a 30 amp fuse (or less).

A 45 amp fuse would be fine with 10sq.mm cable, and should slightly reduce the impedance of the whole circuit.

If you're going to use commonning blocks, why not use eight single sockets rather than four doubles, since these are reported to sound slightly better?

cheers, Martin

quote:

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One last awkward question....Has anyone installed ground earthing AFTER installing a dedicated spur and was there any significant improvement.

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Mick,

I installed my spur today. Much better - more natural, more depth, tighter, more relaxed.

I also purchased an earthing rod, clamp and some chunky 10sq.mm earth wire. Cost was around £15 in total. I have thumped the rod into the ground, but not connected it yet. I expected it to be a real chore and bought a sledge-hammer specially for this, but it took me less than three minutes.

I was going to put it as close to the fuse box as possible, bit I got cold feet. How do I tell where the mains cables are buried in the garden? Assuming a direct line from the house to the road I would have gone straight through it! The gas main also comes in at the same place. Time for plan B.

I will report once it's done. The clamp is easy to add/remove, so I will do A/B's if necessary.

BTW, I found that some of the connections within the fuse box could be tightened up somewhat. When your Leccy connects things up, get him/her to see to this too. Budget for him/her to come back in a month and re-tighten all the new connections, or show you how to do it.

Please don't even think of doing this yourself unless you really know what you're doing. Some of the exposed wires and screws are live even when the mains switch is off. These could probably give you a massive shock 10 times bigger than you could get through a fused appliance.

Also, if you short something inside the box you will probably have to call out the electricity board to repair it. Don't expect this to be cheap, or them to be very happy.

Whoever does the work for you, get yourself a mains tester (see mains tester from Maplins) and check the sockets before you plug anything in. This goes for existing sockets as well as new ones, as connections may have been moved/dislodged inside the fuse box.

cheers, Martin

I have an electrician coming around Friday to give everything the once over and give me a quote etc.

My House was built in 1979 and the fuses are the sort where it employs a strip of fuse wire, which needs replacing if it blows.

Question 1...The sparky has suggested updating these fuses. I can live with that but will it have any effect on the dedicated spur. eg what is the best type of fuse to have or does it make no difference.

Question 2....Is the ground earthing wire connected from the newly installed socket or from the mains box. This would be useful to know so as I can pre plan the route.

When I mentioned ground earthing to the sparky, it was obvious, he thought I was some sort of nutter.

Most importanly, the wife has given her consent so it should be installed within a couple of weeks.

Regards

Mick

I'm now about 21 hours into the warm-up and I reckon this is a bigger upgrade than going from bare CDX to CDS-II (with CDS1-PS & black burndy).

No, really!

Sorry, Mick, only very briefly tried it without the earth rod, results inconclusive so far. Report above is with the rod in-circuit.

"H":-

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Only ONE earth rod ?!?!

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plans have been hatched. Something over-the-top will have to be installed!

Thanks for the link. As specified it doesn't quite work, but I managed to get there in the end.

quote:

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Great in wet weather, poor to nonexistant in dry and or freezing weather

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Err - if you cover the rod(s) with a box won't they dry out and the connection become "poor to nonexistant"?

Thanks for the advice.

Martin

tell all here! Then we can all benefit.

If you don't feel this is appropriate could you e-mail me a copy of the details?

cheers, Martin

Thanks for the offer but please go public, thats the idea of the forum, we all learn that way.

Many thanks

Mick

You are the guy who is doing the favours, and please remember that work always comes first, after all it pays for the HiFi.

Take your time in the office and we will wait patiently for your comments. My sparky isn't coming until Friday, so there is plenty of time.

Thanking you

Mick

I have just spent 45 minutes chatting to the sparky and it should all go ahead on Friday 18th.

Basically he was very Hifi orientated and agreed that a dedicated spur makes sense, especially as my kitchen is loaded with every concievable electrical gadget that man has ever created and yes it pollutes the Hifi like no ones business.

Fortunately the routing is a piece of cake, so I will be doing that and I will leave him to
update my fuse box to latest spec and make the final connections at both ends of the cable.

He was totally against the ground earthing because it will mean fitting a RDC which completely (in his opinion) wipes out the advantage of ground earthing.He gave a long explanation which went straight over my head. Something about line of least resistance.

He will be linking the double socket to 6mm earthing cable back to the mains box and then he does something (I got confused here) to improve the earthing.

He was not happy about fitting 10mm cable because of fitting difficulties and the cable is only 16 meters long, so impedance is not an issue.

If you think this is wrong...please blast back.

Once again thanks for your help.

Regards

Mick

in the end I went for 10sq.mm cable because this is a job you only do once. My cable run is only 5 metres.

Anyway, aren't you doing all the nasty cable routing and leaving him to screw it all into place?

Will the 10sq.mm cable not fit at all, or just make things harder?

He may well be right about the RCD - this is a known issue, although Russ Andrews does recommend the MEM A100HE as being the best of a bad bunch.

cheers, Martin

I would have prefered 10 mm because the additional cost is fairly small in the overall scale of things, but the sparky claims that 10mm cable will not fit into MK sockets.

Did you use 10mm and did it fit OK ?

Regards

Mick

Mick, as one who has just done this, you are in for a treat, sonically and musically speaking!

John