another take on star grounding

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cporro
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Re: another take on star grounding

Post by cporro »

my take on it... and i almost wish i hadn't asked....

the point is that each outlet should have it's own wire back to the ground/nuetral bar.

you could do this by running all wires to each outlet. no daisy chaining.

or you could wire everything daisy chained except grounds. again each outlet would have it's own ground back to ground/nuetral.

then there are isolated recepticals that separate the "safty" or box ground from the 3rd prong ground if you know what i mean. so one extra wire.

i have't yet found an explanation of why star grounding does what it does in basic electrical terms such as ohms, amps, voltage, and circuits. i know it's about getting the same potential/ground for all gear but how star ground does this i don't know.

anyway, it's going in tomorrow.
--
room dimensions: free standing, floor 23'x17', roof slopes short distance (17') from 11'-8'. approx 100 year old sauna house. most framing 2x4, 24 OC. approx 3500 cu/ft.
John Sayers
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Re: another take on star grounding

Post by John Sayers »

Warren of Kansas - http://johnlsayers.com/Pages/jergen.htm - ran a 5 core cable - 1 and 2 looped for +/- and 3 4 5 were individual earth for the 3 outlets.
Speedskater
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Re: another take on star grounding

Post by Speedskater »

Just some more random thoughts:

From the breaker panel to an outlet. The Hot, Neutral & Ground must follow the same route, in close proximity to each other.

One breaker can serve a reasonable number of outlets (the rule for this number vary). To do this in a "star" or "home run" system. Split the Hot wire at or near the panel. Then run the Hot, Neutral & Ground wires to the outlet. At the panel end, connect the Neutral wire to the Neutral bus and the Ground wire to the Ground bus.
Kevin
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Re: another take on star grounding

Post by Speedskater »

John Sayers wrote:Warren of Kansas - http://johnlsayers.com/Pages/jergen.htm - ran a 5 core cable - 1 and 2 looped for +/- and 3 4 5 were individual earth for the 3 outlets.
Unusual for a North American AC power wiring system. Seems more like a G.B. system. 5 core cable rated for building wiring is not readily available in N.A.
Kevin
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Re: another take on star grounding

Post by John Sayers »

Unusual for a North American AC power wiring system
that's what I thought but Warren assured me he is a qualified electrician and that's how he had worked out how to do it.
cporro
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Re: another take on star grounding

Post by cporro »

thx you guys.

whatever star grounding is i hope i have it because the work is done. :D

there comes a time to stop planning and start doing. done!
--
room dimensions: free standing, floor 23'x17', roof slopes short distance (17') from 11'-8'. approx 100 year old sauna house. most framing 2x4, 24 OC. approx 3500 cu/ft.
Soundman2020
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Re: another take on star grounding

Post by Soundman2020 »

Is this true?????????????????????????????????????
Not it is not true. Star grounding is designed to prevent AC ground loops, which most certainly do cause major hum issues if allowed to happen. I see it all the time in video post facilities, and also whenever I have to run live sound at events. All it needs is one idiot musician plugging in some piece of equipment to a "convenient" outlet instead of to the power strips I provide, and its "hum city". Whoever said that you don't need it does not have a clue what they are talking about, and has never worked in the real world of live sound or post facilities.

The issue has NOTHING AT ALL to do with computer power supplies. It has everything in the world to do with ground loop current finding its way through AUDIO SIGNAL cables between two items of equipment that are plugged into different grounds. Even a small AC current flowing through the shield of a mic or instrument cable can induce hum. That's the issue. There's a reason you find those "ground lift" switches all over good quality direct boxes, stage boxes, etc. The manufacturers don't just put them in for fun...
Star grounding with electrical is totally unnecessary???
It is most certainly very necessary. Like I said, I run into it issues with it all the time, both in installed systems and in location systems. Ignore star grounding and get bitten! Believe me, you will be very sorry you ignored it. It isn't that much more expensive or difficult to do than normal daisy-chained grounding. Do it right from the start, and you won't even notice the extra cost. But fixing it afterwards is a major cost, and a major PITA. (Ask some of the clients for whom I've had to fix non-star grounded issues, and they'll tell you all about it.)
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Re: another take on star grounding

Post by John Sayers »

nice to see you back and firing Stuart :)
Soundman2020
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Re: another take on star grounding

Post by Soundman2020 »

Thanks John! I might be "firing", but not really on all cylinders... :D :!:
Speedskater
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Re: another take on star grounding

Post by Speedskater »

Speedskater wrote:
John Sayers wrote:Warren of Kansas - http://johnlsayers.com/Pages/jergen.htm - ran a 5 core cable - 1 and 2 looped for +/- and 3 4 5 were individual earth for the 3 outlets.
Unusual for a North American AC power wiring system. Seems more like a G.B. system. 5 core cable rated for building wiring is not readily available in N.A.
It occurred to me that roadies sometimes use cables similar to this for stage productions. So maybe some spare cable was available or just that he was familiar with this type of cable.
Kevin
Berre
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Re: another take on star grounding

Post by Berre »

Hi,

I have an additional question on star grounding...

While I do understand the principles behind it (and the necessity of it), I was wondering whether the following topology is also considered a safe way to execute this.

I will basically have two rooms: the control room and the live room.
In the CR I would like to have 4 circuits: 1 to power the monitors, 1 to power the console and outboard, 1 to power the PC and stuff, and a lost one to power other stuff like lava lamps, cellphone adapters, etc...
In the LR I will have only one circuit.

It speaks for itself that each circuit will have several outlets, spaced around the room (and well-labeled).

For me it would be very practical if I could do the grounding as in the attached diagram (i'll post them shortly, I have some trouble with drawing them on my new PC with no good SW). It basically boils down to having several star points (per circuit) that then finally come together in the main board.
The reason is that here in Belgium we work mostly with prewired conduits, containing 3 wires (one of them to be used ground). I have no problem running a conduit from each and every outlet to a kind of a subboard within each room and then for each circuit in each room to the main board where the actual circuit breakers will be. This would help me a) having less wires in the main board to connect within the limited space, and b) running the wires from the main board to the subboards in the new slab, without having to decide on the exact postion of the outlets without having build the actual walls, if you know what I mean.

So, does a configuration as in my drawing still count as a star grounding scheme? Should I go for the included alternative? Or should I go the full monty and run a ground wire from each and every outlet to the main board?

Many thanks for your advice.

Greetings,
Bert
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Re: another take on star grounding

Post by Speedskater »

I would go with the first drawing, with the exception of wiring the "live room" to the "control room" breaker panel. The less wire between any and all audio equipment the better.
Kevin
doramider7
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Re: another take on star grounding

Post by doramider7 »

John Sayers wrote:No - The idea of star earthing is that each power outlet has it's own direct back to the power board earth wire so each outlet sees ground directly, not viia the adjacent outlet.
it sounds like you are saying just use a regular outlet and do home runs for the grounds. that's super easy.

so what's the fuss about isolated ground receptacles?
Speedskater
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Re: another take on star grounding

Post by Speedskater »

As I wrote last year: Isolated grounds are good if your power wires are in metal conduit, but not needed if you have non-metallic (NM or Romex) power cables. The Hot, Neutral and Safety Ground wires should be in close proximity to each other and have a one to one to one relationship. If at some location, you split "Y" the Hot wires then the Neutral and Safety Ground wires should be split at that same point. If at your breaker box, an individual circuit breaker has one Hot wire leaving the box then that breaker should have exactly one Neutral and one Safety Ground wire leaving the box. Any one circuit should be wired so that it has as short as possible Safety Ground wires from outlet to outlet.
Kevin
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