Single Phase

[lilith_envy]

Wow thanks sound man!
The problem is it's not built yet, so how far should I go now with the little $$$$.
I am currently running my entire studio in a spare room off 1 GPO ( and lots of power boards!)
I have no noise, spikes, hum or drop-outs.
My worry is earth hum once I get the live room up.

[lilith_envy]

He he, you keep betting my at the "post" pardon the pun.
I need to investgate a little more.
I buy a power conditioner for my rack gear, and allow during the building process for star grounding- though my guy has no-idea what that is!

[WayneD]

........and allow during the building process for star grounding- though my guy has no-idea what that is!

Uh-oh, that's not good.

W

[lilith_envy]

OK,
Star grounding question! Sorry
With sinking the earth rod(s)

Q-Can I place one rod near the sub panel and one on the other side of the slab.
Dividing up which socket goes to which rod via the easiest route?
Picture shown

[Speedskater]

This doesn't look like a "Star Ground" to me.
With a "Star Ground" system all the audio equipment grounds should connect together in the circuit breaker box.This is called a "home run" in the States.
All the "Ground Rods" must (that's MUST) be connected together.
The people with the best information on how to wire a system, that is available on the web are:
Bill Whitlock of Jensen Transformer
Jim Brown of Audio System Group

First read Bill Whitlock's Generic Seminar handout
"Understanding, finding, & Eliminating Ground Loops in Audio & Video Systems.

[Soundman2020]

Q-Can I place one rod near the sub panel and one on the other side of the slab.
Dividing up which socket goes to which rod via the easiest route?

Nope! Bad idea! Like Speedskater said, that isn't a star system. It's exactly what you DON'T want.

Think of it like a star: The "points" of the star are your wires running to each individual socket, rack, metal frame, etc.. The "hub" at the center of the star is one single location, and that is where your grounding rod(s) is(are) connected to.

OK, it doesn't have to physically look like a "star"! The geometry is a star, but you can stretch those star "points" out any where you want. As long as you keep the same general geometry, with only one hub, that's all you need.

In other words, you need ONE, and only one, central point where all the ground wires from everything all join together. That is usually inside your main distribution panel for your studio. Usually this is a long metal "bar" with lots of places to attach the individual grounding wires from all over. That "bar" is the central hub of your star.

Then, connected to that same "bar", is a very thick copper wire that runs out to wherever you have your physical grounding rod(s). Sometimes one single grounding rod is enough, but often you'll find more. When I install video post production suites, I usually specify four copper rods, each 2m long, pounded into the earth roughly in a square pattern, and cross linked with thick copper wire. At some point on the cross-link is the connection to the bar. One again, there is only ONE connection from this "grid" to the actual ground bar in the distribution panel. The aim is to get the lowest possible resistance to ground, and you accomplish that by increasing the contact area, hence four copper rods are better than one (although one might be good enough, depending on your soil type and electrical system), and thick copper wire is better than thin, for the same reason: Lower resistance.

If you have two separate grounding rods with the sockets split between them, as in your layout, then you have two grounding points. So you have the potential for those two points to be at different levels, electrically. Another name for "electrical potential difference" is "voltage". In other words, you might find that there is a different "ground" level voltage at those two points, and therefore current will flow through your grounding wires, which is exactly what you do NOT want to happen! In fact, as soon as you have even a slight ground current in one of those copper rods, perhaps due to the eliminating the hum from a well grounded bass amp for example, then you have no created a potential difference, and also theoretically a ground loop.

Now here's where ti gets confusing: your electrician might think that he can just run a wire between those two copper rods, and thus solve the problem: Wrong! that could make it even worse, since each ground signal now has two paths to ground, with different resistances, and those two paths are absolutely connected in the dreaded "ground loop", meaning that current can flow "every-which-way-whenever". Now you have a really bad problem (potentially). From a purely electrical safety point of view, you can have dozens of ground rods all over the place, connected to individual sockets, groups of sockets, etc. That's fine, for electrical safety, which is all that most electricians are concerned about. But it is NOT fine if you want to eliminate hum and noise. Most electricians are not concerned about that, and don't even think of it in designing the system. They just put grounding anywhere that is convenient, easy and cheap. They build safe systems, not systems that are safe AND ALSO noiseless.

"Star grounding" means one single point to which all ground conductors lead. It means one single connection to physical "earth". Anything more is bad.

One other point: If your electrical code allows it, then you should also consider tying your main "neutral" conductor to ground, at the distribution panel. You can only do that with some types of electrical system, so MAKE SURE TO CHECK! DOING IT WITH THE WRONG SYSTEM CAN BE DANGEROUS!! But if you can do it (if code allows it), then do it! It makes your electrical installation safer, and reduces even further the possibility for electrical noise in your studio. And once again, do it at only ONE point, inside your distribution panel, with a single thick copper jumper between your main neutral bus and your ground bus.


- Stuart -

[lilith_envy]

thanks guys,
I'll read over everything again and try to get my head around it.

[WayneD]

Grounding is as misunderstood as compression is. Both of which, if not done properly can ruin your day.

Nice description on the concept guys. All the green wires connect to the earth, is the way I remembered it.

W

[lilith_envy]

Ok,
Is this more like it?
1 x 2 core wire daisy chained to eack GPO (hot and Neutral)
1 x 1 core earth return of each individual GPO.
So if I end up with 3 GPO's I will have 3 earth returns?

[WayneD]

As I look at your pic I see you have all these grounds coming out and back home.

You run a feed from the panel to...let's say your receptacle for you rack gear and then to the other receptacle in the same rack. Coming in you have your hot cold and ground. You then make another run to you next receptacle. This is all one ground, it just needs to be made continuous by being connected in the first box and connected to the receptacle via a pigtail. The connections in the second box are made directly to the receptacle. So, no extra runs of ground wires back to the panel. I hope I am not confusing you.
You may want to go to your local supply outlet (Home Depot here in the states) and pick up a book on basic wiring. They are very helpful.

W

[WayneD]

Some basic wiring links for you. I hope they are helpful

http://www.acehardware.com/sm-adding-ne ... 84868.html

http://www.ablegroup.net/BasicWiringDiagrams.htm

http://www.epanorama.net/documents/grou ... nding.html

http://www.hometips.com/articles/sunset ... ng016.html

By all means not the end all on grounding. I threw in some other diagrams to get you familiar with the way simple circuits are built. Hope it helps/

W

[Soundman2020]

Ok,
Is this more like it?
1 x 2 core wire daisy chained to eack GPO (hot and Neutral)
1 x 1 core earth return of each individual GPO.

Pretty much. But if you have two sockets in the same physical wall box, then you can just bridge the grounds on those two sockets together, and run one ground wire back to the bar in the distribution panel, provided that you use thick enough ground wire to meet code. Or thicker. Thicker is better. They way you have it is fine, but you could save a bit on wiring by using only one ground run for each wall box.

( Of course, if you don't mind supporting the Chilean copper mining industry, then by all means, add the extra ground wire, and run one wire for each individual socket! We folks that live in Chile would be grateful for you extra business! )

[lilith_envy]

Sound man and guys,
I went to buy the wire for the studio and the guy behind the counter said that it was illegal to run a 2 core cable for GPO's with a seperate ground wire!
I explained my reasoning and he finally said that it would have to be colour coded correctly. Which is fair enough.
I got a quote @ about $190 for a 100m roll of single core earth and a 100m roll of dual core (neutral/hot) cable. Both are just the standard plastic covered OZ style cable.
Is it legal?

[Soundman2020]

Is it legal?

Where I live it sure is! In fact, not only is it legal, it is actually code for retrofitting old residential buildings that were built with no grounding.

But I live in Chile, and you don't! So you'll have to check your local code for your area.

Round about now would be a real good time to have an electrician friend on hand!


- Stuart -

[Speedskater]

When running new wires, it is best to have the hot, neutral and safety ground conductors as close to each other as practicable. That is in the same metal or plastic conduit or in the same multi-conductor cable. For reworking old wiring try to have the safety ground wire follow the same path as the hot and neutral wires.