Separate house grounding

[Moby]

Guys, I'm in the mood for digging the separate ground (technical ground) for my studio and separate the rec. equipment from the rest of the house.
I know something about, but will be nice to have some reading or to share experience with others.
So, my question is, do you know something about and of course will be nice to have some drawings.
BTW, is it possible to measure the "goodness" of house grounding in some DIY way :?: :wink:

 

[Freq Band]

http://www.surgex.com/pdf/PowerGround_0206.pdf

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[Moby]

Thanks, this is really detailed readin' :grin:

 

[Moby]

Pardon my ignorance about your power system but I'm sure that it's totally different that what we use here in the states in terms of ground and the role of neutral.

Yes, power system is different, (220-230v 50hz) but grounding should be the same term, like "lowest impedance to ground". (only if you are watching from political side :wink: ). I'm joking' of course.. :grin:
I was thinking about digging the proper power ground for audio.
I don't think that is different. Maybe I'm wrong. If I am wrong, this is the question for European guys :green:

 

[Moby]

So does the utility provide a ground connection with the drop cable or is it somehow derived from an earth tie at your service entrance? Maybe cold water pipe tie or a driven rod?

I'm not sure, simply I cant find where is my house "grounded". Unfortunately its build 1932. so plans are not available. I think that is grounding really poor, that's why I'm thinking about making the second one and to be used only for studio equipment. As you mentioned hum is changing like weather and depends from rain :evil:
That's making me crazy.
I already tried to make experiments with unplugging some of equipment from ac power or to change the "polarity" of outlet but didn't find any progress.
And I have three phase system. One phase I use for conditioning, second for lighting and third for audio equipment.
BTW, voltage is stable :?
(BTW, is my power balanced? I'm not sure )

 

[Moby]

Is your service drop aerial or buried? How many wires come in? Three, four? Is one of them uninsulated?

It's aerial. Outlets are 3 wire green/yellow - ground, brown-0 and blue - phase. Main wire is 5 wire( I think).
In fuse locker (or how you call that :? ) is one flat zinc stripe uninsulated.
That's ground. But I don't know from where is coming that :?:

With a house built in 1932 you may not have a ground. Don't know about Europe but I'm really suprised to see three-phase there.

You forget that Tesla was Serbian :wink: Really it's three-phase, I'm sure.

Is the hum less with rain? Or are you like us right now and have forgotten what rain is like?

Yes, it's lees hum with rain. Right now it's raining :grin:

BTW, is it possible to measure ground impedance by some DIY method?

 

[Brian Roth]

I can only speak about USA single- and 3-phase systems, but any "extra" grounding electrode in a building MUST be bonded back to the "main" grounding node for the structure (typically found at the main fuse/circuit breaker panel) in order to meet NEC building codes.

The reason is for safety, since any grounded wire will be at approx. the same voltage as any other grounded wire in the structure. That's why any metallic water lines also need to be bonded to the same grounded node.

I've seen some elaborate grounding systems used for radio/microwave transmitter sites. Typically these consist of multiple 8' long grounding electrodes driven into the dirt at maybe 8' intervals, then linked together with 2GA copper wire that is "CadWelded" to the electrodes.

Bri

 

[Moby]

Guys, thanks for helping. :grin:
I checked my wires, there is definitely 5 wires coming to my main fuse/circuit breaker panel. 3 phase, 0 and ground from transformer station. Then this "transformer" ground is connected to the panel together with house ground (the zinc stripe wire). From that point all phases are traveling together with 0 and GND . All 0 are on same potential with ground. Huh, I hate this, I'm always confused when I talk about :?

 

[Moby]

Thanks again.

I wonder if the electrical code in Serbia permits additional grounding electrodes at the service entrance and do you have one

Yes, it's OK here to have additional grounding electrodes.
BTW my situation looks like this

an you see any evidence that there is some local ground rod or cold water pipe ground also connected to the panel ground buss? Or, is the safety ground referenced only at the transformer pole? Here in the states with three phase the neutral (0) and ground are usually bonded in the panel and then earthed with a rod, tied to building steel or galvanized riser pipe.

Yes, the 0 and ground are bonded in the panel and I see the ground stripe going somewhere... Maybe is connected to ground electrode, but don't know...

Please be very careful and do not hesitate to call an electrician to find out these answers. Have him or her re-torque your panel connections while they're in there

:grin:

 

[Moby]

Thanks guys :thumb:
I will call some local "high voltage expert" to help me, really I have headache when I think about. :evil: This is my "old" problem, and I decided to fight against recently :wink:

 

[CJ]

Thats called a "wye" system.
Your lucky, if it was a delta, you might not have had a ground brought out.

 

[Moby]

[quote author="CJ"]Thats called a "wye" system.
Your lucky, if it was a delta, you might not have had a ground brought out.[/quote]
Kill me if I understand you :? Do I have to laugh or to cry :wink:

 

[CJ]

No, be happy.

 

[Moby]

:grin: :grin: :grin:

 

[Brian Roth]

I can only speak from the viewpoint of USA wiring systems and the "code" (NEC).

In more than a few office buildings, the solution was to install an iso transformer (480V to 240/120 V...480V being the internal distro..that was a 480/277V system).

I believe the "center tap" of the derived 240/120 single phase could have had it's own grounding reference and complied with the NEC, but in an office building..where do you find that?? No way in hell to stab a new "spike" into the dirt!!

Hence, the center tap of the "derived" 240/120 was also bonded back to the building's ground node.

And then there was the day when a new PBX was installed on the 11th floor...and Nortel required a FAT grounding lead back up to the "grounded" node in the xfmr cabinet on Floor 12..that xfmr ran floors 10, 11, 12.

This sometimes boggles my mind..........

BUT, the recording studio on Floor 1 had a new iso xfmr, fed from the building's 480 internal service. The CT of the 240/120 single phase was bonded to the building's "ground node" (and I don't know what that was...but in a 22 story highrise you worry about lightning strikes, which is one arena where the NEC "cares").

We had essentially NO hum issues, but geeeez....more than a few blow outs during a thunderstorm.

In hindsite (I did NOT do the electrical engineering for the entire skyscraper, not that I was qualified to do so), it appears there might have been some sort of weaknesses in terms of lightning hitting the top of the building and then blasting through unexpected pathways.

I know for a fact (ie, via my own eyeballs) that the top of the skyscraper had all sorts of lightning spikes and PHAT cables running all over the place..tied into the steel structure IIRC.

In another place in Tulsa (12 story building), I know that a ligntning hit totally SMOKED all of the internal AC distro/riser. All off the riser cables were vaporized. The AC Mains system in that building was toast, and the entire building was totaly dead for weeks, yet it didn't burn down.

So, two different things...day to day is #1:

All grounded points in the building need to be at the same voltage potential to avoid hazard. IE, the water pipes need to be bonded to the AC mains ground node. etc etc

#2: OMIGAWD when lightning hits.

NEC attempts to address both.

Bri





Bri

 

[Moby]

Guys, i read this http://www.groupdiy.com/index.php?topic=17322 and think that most of the things about my problem are clear now. Unfortunately my English is not so perfect to explain.
But, let's say that I will bury some additional ground ( 3 electrodes deep enough and with distance, let's say around 3m each).
Of course, I will ask some professionals to do that for me :wink:
Thanks for helping.
Cheers :guinness: