Driving a new ground spike

[moamps]

My point, perhaps not blunt enough, was that posting information about UK electrical safety from a site outside of the UK (in this case Serbia, but would be equally at issue were it USA, France, Germany, wherever) from an unknown organisation with content of dubious origin and correctness, doesn't really help a thread on a safety-related topic. Each country has its own electrical codes for a variety of reasons, so you cannot compare safety earthing systems unless treading very carefully.

Using a whois locator, I found very simply that the domain is hosted in Utah, Provo (I passed through that city once on the way to Yellowstone, which is certainly not in Serbia). Picture below. On their Facebook I found a linkedin link that says they have offices in California and Birmingham UK. So much for bad and unreliable servers from Serbia.

As for the specific diagram in post #132, that shows a "TT" system as it is called in the UK. But there are two other earthing systems (TN-S and TN-C-S), and also note that the diagram posted does not show the complete earth circuit as it fails to show the supply source transformer with its Neutral connected to ground as well.

Yes, I showed in my post the TT earthing system (where PE is not connected directly to Neutral, anyone can find a bunch of pictures of how this is done if they search for the term “TT earthing system”) in order to show that grounding systems are not the same in all countries. Therefore, it cannot be argued IMO that this can only be done in one way. This further results in the fact that the optimal solution for grounding one audio studio depends on several factors that are not the same for everyone.

 

[MisterCMRR]

(in part):
Regardiong that isolation transformer. I suppose it cOULD act as a form of serious surge voltage limiter in that diven a surge of a couple of KV (the core would (temporarily) saturate so limiting the secondary side surge to ??? hundreds of Volts. It will of course increase the IMPEDANCE of the supply reaching your studio so the HiFi brigade will criticise you for not having a direct, infinitely low impedance supply direct from the power station. This will of course muddy your lower mids and increase HF flutter.

I don't think an isolation transformer would provide any surge protection via magnetic saturation. Remember that magnetic flux density (and thus saturation) is a function of frequency. While only a few hundred volts would surely saturate the core at power frequencies, standardized (IEC) surges from 1 kV to 4 kV for test purposes are impulses with a width of 50 µs (at 50% amplitude points) and decay exponentially to simulate lightning induced surges. As such, their equivalent frequency is in the area of 10 kHz. So the transformer might attenuate the spike but it would be due to either arcing and breakdown or just the HF attenuation of leakage inductance ... but not saturation. Admittedly a fine point, but I always want to promote a better understanding of transformers.

 

[Matt Syson]

Hi MisterCMMR
Thanks for the technical observation and indeed the possibility of such a transformer providing really useful protection is slim. I suppose gear that was switched off at the time of a strilke would not have their mains switches 'tested' so a greater chance of survival but it is all a matter of luck.
while trying to find out French regulations about whether an inbuilt cooker should have a RCD or any other particular fusing rerequirements the website for Legrand (an 'upmarket' manufacturer of electrical paraphernalia across Europ at least, has 'surge limiter' units to protect domestic gear against local surges due to lightning strikes etc. As they are engineered to do the particular job they would be 'better' than using a 'random' transformer and if you are in a location prone to lightning possibility having the transformer, since it is just sitting there at the moment, plus a surge protector (which obviously complies with electrical 'code' might provide some benefit but in reality simply wiring the studio correctly is just fine.

 

[abbey road d enfer]

I believe that Rob's intent was not to use the iso xfmr for lightning protection, but for providing a clean feed for his studio gear.
The iso xfmr , properly grounded, would probably reduce the transmission of common-mode conducted emissions. I don't think it's enough to clean the mains, but considering it already is there at no cost, why not?

 

[moamps]

I would like to add two or three tips that are the result of my considerable experience with the use of isolation transformers, which may be useful to someone.
1. Mains EMI filter rated for maximum current consumption should be installed at the transformer input. If there are multiple outputs from the secondary transformer, each may also have a dedicated mains filter.
2. The transformer should have a soft-start. The initial magnetizing current of a larger transformer is always quite large and almost always turns off the breaker at the transformer input (even if it has a slow response).
3. The transformer load should be switched on with a delay after the transformer is switched on using the relays. If there are multiple outputs from the secondary of the transformer, sequential switching on can be made. This feature is great if short outages often occur and often saves devices from malfunctions.

 

[Rob Flinn]

Thanks for the tips people. My intention in using the transformer was to provide a small amount of isolation ffrom the farm equipment in the area. I don't expect it to be a one shot solution, but my analogy (right or wrong) was that because it had a limited frequency response it might help to filter out any h.f noise from the switching on/off of plant at the local farms. I was planning to use a filter before the transformer as well. I bought a LC type 32A filter to use before but having read some of Bills lecture notes I'm not sure how effective the filter will be. The switch I'm using for before the transformer came from a skip at a place I was working last year, & is industrial switch gear, the kind of thing that comes in a grey metal box & you can't open the door with out the switch being off. Roughly as in the diagram I'm about to attach. Any critique or observations would be welcome.

 

[neil.johnson]

Using a whois locator, I found very simply that the domain is hosted in Utah, Provo (I passed through that city once on the way to Yellowstone, which is certainly not in Serbia). Picture below. On their Facebook I found a linkedin link that says they have offices in California and Birmingham UK. So much for bad and unreliable servers from Serbia.

From the website itself:
https://www.electricaltechnology.org/privacy-policy

Governing Law

These Terms will be governed and construed in accordance with the laws of Serbia, without regard to its conflict of law provisions.

I really wouldn't go by the whois record, servers can be in any country, redirects, etc. Notice, for example, in your screenshot the registrant country is "is" which is Iceland.

But... meh... whatevs...

 

[Tubetec]

Theres a different kind of breaker used for large transformers and motors , Im not sure the specific terms for it and as we've found out terminology varies with geography .

 

[moamps]

I really wouldn't go by the whois record, servers can be in any country, redirects, etc. Notice, for example, in your screenshot the registrant country is "is" which is Iceland.

I can not believe it. Domains are strictly tied to IP addresses assigned to servers internationally. And that information can't be faked. The registrant indicates where the domain name is registered. They registered it in Iceland. Web site is hosted in USA. So what? My small website is hosted in Croatia and the name is registered in Canada.

To end this crazy correspondence, I would just like to emphasize that I have nothing to do with that website (I happened to find their scheme on the web, and linked it) or with Serbia (I don't even have any good memories with Serbia). But I really can’t stand this kind of hypocrisy. No matter to whom. And maybe I would understand your criticism that they made a mistake on the site, but obviously they didn't, the schematic shows the TT earthing system correctly.

P.S.
The sentence you linked to is a standard sentence used by many websites. Try to google it. I don't know why they mentioned Serbia. Maybe they copied that part from a Serbian page and forgot to change the state.

 

[Tubetec]

As far as I remember its a 'C' style breaker , with a particular peak load spec.