Noise and DC on mains and new radial

Thanks FT.

Putting an isolation transformer between the meter and the main CU for the house is a bad idea - it'd then have to be rated at 125A (125% of fuse rating and main fuse is normally 100A).  It also then won't provide isolation from the effects of other electrical items in the house.

Better to use a separate CU (connected to the meter tails by Henley blocks)) for the HiFi circuit and use the isolation transformer in balanced mode (i.e. wired CTE) on that.

KRM posted:

I also used a consumer unit which has a 100a isolator switch instead of an RCD (supplied by Russ a Andrews). This is fine as long as the socket is labelled for hi-fi use only. Finally, I have an earth spike.

 

Unless you have a TT earthing arrangement (either originally installed or having converted to this when your earth spike was installed), it can be potentially very dangerous to fit an additional earth spike; particularly as many (most?) houses in the UK use the PME (TN-C-S) earthing system and using an extra earth electrode with this can result in fires if there's a fault.

You should also note that you NEED an RCD in ALL circuits with TT earthing, so one of your two arrangements doesn't seem quite right.

Please get this confirmed / checked by an intendant qualified electrician whose Part P certification is up to date.

Hi KRM considering using 2x6mm as you have ...... however, at first thought - I would not have thought it possible to get 2 x 6mm into a 13a socket cable input point ........... when yours was done what make unswitched socket did you use.....did all go smoothly.....

Hi Huge,

The consumer unit comes with certification that it is ok when used with the labelled socket.

I know what you mean about earth spikes and I thought they weren't allowed, but I was reassured by the electrician that it's perfectly fine the way he's done it (I know him and he's good). Naim advise still recommends mains spikes, by the way (or the Naim advice passed to me by the dealer does).

Keith

Richieroo posted:

Hi KRM considering using 2x6mm as you have ...... however, at first thought - I would not have thought it possible to get 2 x 6mm into a 13a socket cable input point ........... when yours was done what make unswitched socket did you use.....did all go smoothly.....

Hi Richieroo,

The electrician said it would be easier to wire two x 6mm into the unstitched MK double socket than 1 x 10mm.

Keith

KRM posted:

I also used a consumer unit which has a 100a isolator switch instead of an RCD (supplied by Russ a Andrews). This is fine as long as the socket is labelled for hi-fi use only. Finally, I have an earth spike.

I'm surprised to see RA selling this consumer unit, which is made of plastic, and will not conform to current UK electrical regs in the majority of installations. That doesn't make it illegal to sell it, but getting it signed off under the current IET regs is another matter.

ChrisSU posted:

KRM posted:

I also used a consumer unit which has a 100a isolator switch instead of an RCD (supplied by Russ a Andrews). This is fine as long as the socket is labelled for hi-fi use only. Finally, I have an earth spike.

I'm surprised to see RA selling this consumer unit, which is made of plastic, and will not conform to current UK electrical regs in the majority of installations. That doesn't make it illegal to sell it, but getting it signed off under the current IET regs is another matter.

Hi Chris,

No need to be surprised. The "the plastic, self-extinguishing enclosure conforms to UL94".

Keith

They withdrew the old one due to the new requirement to have an enclosure as the the metal case adversely affected the sound quality, apparently.

KRM posted:

I also used a consumer unit which has a 100a isolator switch instead of an RCD (supplied by Russ a Andrews). This is fine as long as the socket is labelled for hi-fi use only. Finally, I have an earth spike.

 

Please, please check your earth electrode has been validated by an electrician. Installing an earth electrode on a PME based earthing system...(  this is where your utility  distribution has a shared primary low impedance path to earth, which is common in the U.K. ) ... could  result in potentially lethal situations but almost certainly cause considerable damage to your connected appliances  if there are certain faults conditions in your utility supply. Think damage similar to some types of none direct lightning strikes, but you almost certainly won't be covered by insurance.

Now if your 'spike' is relatively high impedance to earth (like bonding a cold water pipe) and not a proper earthing electrode, then the chances of issues will be significantly reduced but it will almost certainly be ineffective at doing anything relevant.

if you want local true earthing, you need a TT system, and if you haven't one you need to pay an electrician to convert your utility supply. I have done this, and my earth electrode is a formal impedance validated electrode installation with my primary house supply earthed to it... and yes definitely worth doing properly and my noise levels dropped hugely. Audio was only my secondary motivation for doing this but hugely benefitted.

Simon (all).  I would ban the sale of earth spikes in UK except to Part P qualified electricians.  Too many people are playing with stuff they have not a clue about.   I have a good example of this only a few weeks ago when I got into conversation with someone who was planning to dig up an area of his garden to install an earth plate (& would I help with the wiring).  He read that the larger sq/ft area plate did so much more than a spike & would turn his TV into something amazing.   First it took me quite a while to make him believe his property does not have a ground spike & the words of wisdom were from a USA www & completely non-applicable to UK & to his house that has PME (TN-C-S).    

So Mike, should my sparks be earthing my radial back to dedicated CSU only with no mods to earthing at all?

The spike was fitted by an electrician.

The advice to fit a spike came from Naim (via the dealer), not from Russ Andrews, although I did ask him if it would be ok and he said it would be "fine" as long as it was fitted by a qualified electrician.

The advice from Naim was:

"Use a dedicated earth for the sockets. Use the house earth to protect the cable run, but don’t connect it at the sockets. Get the sockets’ earth from a totally separate rod outside the house. The rod should be as close as possible to the sockets, but needs to be somewhere where the ground doesn’t dry out too much."

Keith

Indeed, Mike, though I never endorse banning, as earth electrodes are legitimate... of course there are different sorts and it's not all about electricity utility regulations... in RF engineering both amateur and professional they can be essential and nothing to do utility supply, but for those most take exams (professional and amateur) where these matters are addressed.

I also think there is a lot of myth and mumbo jumbo discussed on the web about earth electrodes, utility earthing and the remove RF. Simply earthing a lead doesn't remove RF, RF voltages don't work that way. To sink a RF wavelength voltage the source to point of highest impedance of the electride be an odd value quarter wavelength in length...  if the length is at an even value quarter wavelength it will have no effect in sinking the RF what so ever... that is why for RF sinks you can use a star setup with different length radials with an electrode at the end of each radial which is what I use for my non safety earth utility electrode.... but I could safely facilitate until I converted my domestic supply to TT.  I optimise my RF sinking up to 30 MHz (approx 10 metres) and I feel it it is up to these frequencies/wavelengths that are most likely to affect audio content ccomponents.

But yes a single earth electrode will have minimal RF impact if any. The mesh idea you see in the states for amateur tinkering seems to work on the assumption the ground is super conductive, and the mesh is between your earth feed and couples to your assumed  highly conductive soul thereby modelling a large with respect to the relevant wavelengths highly conductive ground plane.... I am not aware of our soil in the UK being super conductive, and even then as you say you should only tinker once your utility supply is converted to TT.

KRM posted:

The spike was fitted by an electrician.

The advice to fit a spike came from Naim (via the dealer), not from Russ Andrews, although I did ask him if it would be ok and he said it would be "fine" as long as it was fitted by a qualified electrician.

The advice from Naim was:

"Use a dedicated earth for the sockets. Use the house earth to protect the cable run, but don’t connect it at the sockets. Get the sockets’ earth from a totally separate rod outside the house. The rod should be as close as possible to the sockets, but needs to be somewhere where the ground doesn’t dry out too much."

Keith

 

Then Keith you should have a certificate with your house documentation to say your utility supply is now (or was) configured as TT. Please check you have that or obtain from your electrician... if something goes wrong your insurance company might need to see that. A properly situated and installed electrode will be provided so environmental variations have minimal impact (suitable depth in shaded location with good local ground conductivity) , and certainly not require user intervention to keep moist (would need to be salty water BTW).

Also note a single electrode DOES NOT remove most RF from the mains, it now allows you to add an additional RF sink set of electrodes safely. If in doubt discuss with a CEPT class 1 licence holder (happy to do this off forum).... electricians don't need to study this or be examined on this in the UK. Earth electrodes utility specifications  in the U.K. are for safety and NOT RF... that is covered separately.

eagle3333 posted:

So Mike, should my sparks be earthing my radial back to dedicated CSU only with no mods to earthing at all?

If your supply is PME (TN-C-S)  Yes (no mods required) .   If your supply has another earthing method,  (there are five categories although only three are in common use)  Your electrician is best placed to advise.

Hi Simon,

I just spoke to the electrician. He will provide me with an installation certificate ( to certify that it has been installed by a qualified electrician). He confirmed that the circuit is connected to the utility earth. Only the socket (so the hifi) is connected to the spike. It isn't duel earthed, therefore. He says it's legal and safe.

You may be right that the spike is pointless from the SQ angle, but Naim recommend so...

Keith

Keith, good stuff, so just to be clear so your certificate converted your house to TT?

if not and you have multiple earth zones which can be used for example where there are outbuildings, static caravans etc, he / you should ensure that there is sufficient physical separation between zones if of a different type such as PME and TT so no person, domestic extension lead or appliance can straddle the zones. So an example you couldn't touch a light switch or metal radiator and the Naim at the same time if earthed by different zones, or you couldn't power a vacuum cleaner from one zone and touch the Naim in another. The risk is from the massive earth current flowing between those zones in certain fault situations that may not be immediately otherwise readily apparent.

But yes local earth could improve SQ if you have noisy earth coming from outside (PME) or from other appliances in your house (zoned) such as a noisy fridge compressor switch.

The certificate will simply say that it has been correctly installed by a qualified electrician.

The domestic ring and the hifi ring are connected to the earth from the electrical supply. The socket is connected to the earth spike, as per Naim's recommendation.

I think you're suggesting that the earth from the supplier or the rod could fail and that would be a problem if you touched the hifi and a light switch at the same time?

Keith

KRM posted:

The spike was fitted by an electrician.

The advice to fit a spike came from Naim (via the dealer), not from Russ Andrews, although I did ask him if it would be ok and he said it would be "fine" as long as it was fitted by a qualified electrician.

The advice from Naim was:

"Use a dedicated earth for the sockets. Use the house earth to protect the cable run, but don’t connect it at the sockets. Get the sockets’ earth from a totally separate rod outside the house. The rod should be as close as possible to the sockets, but needs to be somewhere where the ground doesn’t dry out too much."

Keith

 

If you are doing this then you MUST have an RCD in ALL circuits; without this the arrangement just isn't safe.

(As a very minor point, how are you running the extra earth wires as this will affect the audio & RFI performance?  Also note that they must be green/yellow insulated.)

KRM posted:

ChrisSU posted:

KRM posted:

I also used a consumer unit which has a 100a isolator switch instead of an RCD (supplied by Russ a Andrews). This is fine as long as the socket is labelled for hi-fi use only. Finally, I have an earth spike.

I'm surprised to see RA selling this consumer unit, which is made of plastic, and will not conform to current UK electrical regs in the majority of installations. That doesn't make it illegal to sell it, but getting it signed off under the current IET regs is another matter.

Hi Chris,

No need to be surprised. The "the plastic, self-extinguishing enclosure conforms to UL94".

Keith

UL94 is a series of flammability tests for plastic materials. The fact that the body of the unit has been made from a material that has passed one of these tests does not mean that the installation conforms to the electrical regs.

KRM posted:

The certificate will simply say that it has been correctly installed by a qualified electrician.

The domestic ring and the hifi ring are connected to the earth from the electrical supply. The socket is connected to the earth spike, as per Naim's recommendation.

I think you're suggesting that the earth from the supplier or the rod could fail and that would be a problem if you touched the hifi and a light switch at the same time?

Keith

Keith, no the risk comes from a fault in the distribution such as a neutral fault at the substation or neutral line fault on a return, in such circumstances the return path may then become any low impedance earth path, the current will seek out the lowest impedance to ground.Now this may be all the relatively high impedance water pipe bonding points in the distribution, the voltage will drop and then the substation hopefully  would then trip off... however if there was a link between the supply earth and your local earth electrode, your entire substation return current could be through that until the substation trips. If there was a wire between the two earths that would almost certainly melt like a fuse wire possibly causing a fire, and more importantly if there was a person bridging the two earths they would be burnt/electrocution if for example brushing against the Naim whilst operating a light switch or another appliance during this fault condition. So yes there are a chain of events that need to happen, but that is what safety is all about i.e. Managing for those cases ... we all know too well when recently what happens when these risks are possibly ignored....

In a TT setup the earth at the supply (if there is one)  and distribution is decoupled therefore in such a neutral fault situation there would be no return path from your local area distribution  via your earth electrode.

Huge posted:

KRM posted:

The spike was fitted by an electrician.

The advice to fit a spike came from Naim (via the dealer), not from Russ Andrews, although I did ask him if it would be ok and he said it would be "fine" as long as it was fitted by a qualified electrician.

The advice from Naim was:

"Use a dedicated earth for the sockets. Use the house earth to protect the cable run, but don’t connect it at the sockets. Get the sockets’ earth from a totally separate rod outside the house. The rod should be as close as possible to the sockets, but needs to be somewhere where the ground doesn’t dry out too much."

Keith

 

If you are doing this then you MUST have an RCD in ALL circuits; without this the arrangement just isn't safe.

 

 

(As a very minor point, how are you running the extra earth wires as this will affect the audio & RFI performance?  Also note that they must be green/yellow insulated.)

That's why I called Russ Andrews and they said it was "fine".

The Consumer Unit is sold with a socket labelled for "not protected by RCD - for hifi use only". 

Keith

Simon-in-Suffolk posted:

KRM posted:

The certificate will simply say that it has been correctly installed by a qualified electrician.

The domestic ring and the hifi ring are connected to the earth from the electrical supply. The socket is connected to the earth spike, as per Naim's recommendation.

I think you're suggesting that the earth from the supplier or the rod could fail and that would be a problem if you touched the hifi and a light switch at the same time?

Keith

Keith, no the risk comes from a fault in the distribution such as a neutral fault at the substation or neutral line fault on a return, in such circumstances the return path may then become any low impedance earth path, the current will seek out the lowest impedance to ground.Now this may be all the relatively high impedance water pipe bonding points in the distribution, the voltage will drop and then the substation hopefully  would then trip off... however if there was a link between the supply earth and your local earth electrode, your entire substation return current could be through that until the substation trips. If there was a wire between the two earths that would almost certainly melt like a fuse wire possibly causing a fire, and more importantly if there was a person bridging the two earths they would be burnt/electrocution if for example brushing against the Naim whilst operating a light switch or another appliance during this fault condition. So yes there are a chain of events that need to happen, but that is what safety is all about i.e. Managing for those cases ... we all know too well when recently what happens when these risks are possibly ignored....

In a TT setup the earth at the supply (if there is one)  and distribution is decoupled therefore in such a neutral fault situation there would be no return path from your local area distribution  via your earth electrode.

Hi Simon,

Thanks for the clarification. I'm looking into it and will bin the spike if there's any issue with safety or insurance.

Keith

Keith, really sensible approach. However it may be entirely appropriate for your house to be put to a proper TT utility supply configuration. It's almost certainly not a big job for your electrician, although you will have a new earth cable running from your distribution board to your new primary electrode that your electrician will additionally validate  the impedance of. You will almost certainly get SQ benefits if you are getting them at present... and you know you will then have a suitable  and most importantly safe setup that gets you closer to your music