Star Grounding System Question

Hey everyone. This is really cool that this section was added to the forums! Lots of great information. I am in the process of wiring all of my rooms (electrical) right now and have a question regarding the Star Grounding System. I've searched through and through everywhere I thought possible on the internet and have found nothing. There are many sites where people say they've used it for there electrical system but none of them say how to actually impliment it! Does anyone know of a site where this information can be gathered? Is it imperative that I use this system in my studio? My goal is to have no grounding or ground loop problems from circuit to circuit. Is it possible? Thanks everyone. M

http://www.saecollege.de/reference_mate ... stics4.htm Details the star grounding system. I have an old joke. The Better the Ground, the better the sound.

Thank you Brian. A couple of other questions if I may... 1) By reading that section at the SAE site, am I correct in saying that when using your typical 14-2 or 12-2 standard wire for outlets, I should disregard the provided ground wire and run a seperate, bare copper wire for my grounds? 2) When using this method, does each circuit get its own grounding path back to the service panel? 3) Does each circuit ground at its own rod in the ground? My electrical system for my building is just a 100amp service off of my house service. It terminates at the studio building with two grounding rods just outside the building. Thanks for all of your help. M

Sorry for the wrong spelling BrYan! :oops: M

Hello Hi Def,

1) By reading that section at the SAE site, am I correct in saying that when using your typical 14-2 or 12-2 standard wire for outlets, I should disregard the provided ground wire and run a seperate, bare copper wire for my grounds?

I guess my first question to would be: Are you running Romex w/ 14/2 or 12/2? Or will you be running conduit? If you're running Romex, and depending if your having this inspected by your local codes, you may want to run a home run to each outlet. If your running conduits, and using metal enclosures, it will be simpler. You can tie (or daisy chain) the Hot and Neutral together for several outlets, but you want to run a separate ground wire for each outlet. eg: a quad outlet box, you would have 2 ground wires (one for each isolated ground outlet), and you'll also need one (as I found out later) for the box enclosure itself. In other words, for each outlet you have, you want a home run ground wire that runs back to the panel where they all join together, and then to your rod.

2) When using this method, does each circuit get its own grounding path back to the service panel?

Answered above.

3) Does each circuit ground at its own rod in the ground?

You just have the one rod normally. In reading other posts, I've seen some people use a couple rods and tie them together, so there's always a good ground. :D Aaron

Here's a link to a 6 page thread on RO where we thrashed this to death some time back - rather than regurgitate all of it, you can find pretty much everything you need here, including relevant code sections to show your inspectors, electricians, etc - http://www.recording.org/posts16729-0.h ... highlight= Grab a cup of coffee and some snacks, this will take a while... Steve

yeah, what they said. LOL

Hey thanks everyone! That article on recording.org was great....but.... :? Still a little confused. The way my current power is run to the building is as follows. From the main house panel I'm running 100amp service to the studio building via a 3 wire #4 cable. No ground. Just two hot and a Nuetral. OK...It's hooked up to a 100amp panel in the studio. I've installed a grounding bar in the panel and took a #6 cable from there out of the building to two grounding rods 8 feet apart. All is good right? :) There was talk in this article that if in my situation, as described above, that the ground and nuetral must be bonded! This totally confuses me and is contradicted further in the article as nuetral holds power and would introduce a ground loop. I believe Rod G. advised not to run the IGs back to the same panel for fear of introducing interference, but to install a seperate box with a grounding rod that is bonded to the studio main panel. Hope this isn't confusing the way I've worded this. Bryan: In the diagram you provided from SAE, where is the center point of the star? By this I mean are all of the circuit's outlet grounds tied together somewhere outside the panel and then that one wire carries to the ground inside the panel? Thanks everyone for your help. Hopefully this isn't becoming a pain in the .... M

Ah the flexibility, you can have all the grounds meet inside the panel, wrap them in electrical tape so that they do not touch the panel in any way and run a nice copper wire strand outside to your grounding rod. Dont waste your time getting confused. Do not tie the Ground and the nuetral together. Never a pain. I have installed a number of these type of grounding systems even before I read this article. All my years doing live sound and dealing with .04v AC on the ground side of things and having to figure out methods to quiet that mess down. :) I tend to carry ground rods with my PA deals and my live recordings. you never know when you gotta break it out and hammer it in. ;)

Thanks Bryan. You've been a tremendous help! One more question and then I think I got it. Ok actually two! :wink: 1) In your experience with installing these grounding systems, did you put the IGs in their own conduit or did you just run it along witht he romex? 2) When you say tape all of the grounds and avoid touching the panel with them, There's where you lost me. All of my other grounds from lights and other outlets are coming back to that same grounding bar in the panel...correct? :? Or are you saying bring IG wires in the box, bypassing the panels ground bar entirely, and run it directly to the grounding rod outside? Your help is very very appreciated man! Thanks a ton. M

In a commercial install they usually run individual wires for hot, neutral and ground through conduit. That is how they can run all the grounds to a separate box with ease. It is a single wire all alone. However when using romex the 3 wires are running together. You can, when the wire approaches the box split it and run the hot and neutral into your service panel and the ground to the separate grounding box. However you attempt it make sure that your grounds for the studio are seperated from the grounds from the rest of the facility. If you can install a separate breaker panel just for the studio that is even better then it would not matter if all the grounds came to your grounding strip that you ground to an outside grounding rod.

Hey Bryan, thanks for the quick reply! Yes I am running a seperate box for the studio. It's a whole seperate building with 100amp service from the house. So...I can tie these IGs directly into the panels grounding bar? I don't need a seperate ground box as suggested on the recording.org article? Sorry to ask again but, is it ok to run this 12Gage grounding wire along with the romex, not in conduit? I've started wiring already and have run the 12-2 romex (not using the provided ground) and then running another single 12gage wire for the isolated ground. They are run next to each other and not in conduit. Is this kosher? I'm concerned about grounding in the same panel because the rest of the buildings power needs come off of this same panel. Like the AC, lighting and other stuff you have in a studio. Maybe it's nothing to be concerned about. Thanks for your help Bryan. M

Yep you'll be fine. Just keep all the studio electrics on one leg of power and the ligting on the other leg of power. with most boxes every other breaker position is the same leg. IE brkers 1,3,5,7,9 = same leg 2,4,6,8 = same leg so 1 would be a differnt leg than 2. :) And the grounds from the studio electrics keep those isolated from the other grounds like I indicated above. I have never had any issues doing this. Been wiring small studios since 1994. No hums no buzzes since. :) Including doing Audio for video Studios.

Bryan..........You Kick Ass! Thanks a million! I've been starting to wire all the stuff and everything you say makes perfect sense, and I'm understanding exactly what to do except one thing! :? When you say isolate all grounds on the studio electrics from the rest of the stuff, do mean at the panel as well? Because ultimately, all the studios grounds from all of the lighting etc. will come back to the ground bar in the panel. Therefore, it's not technically isolating the ground is it? Should I install a separate grounding bar and stake specifically for my studio electrics? Sorry man to keep this going but after this one issue is resolved I'll be straight with the whole iso ground think I think! :lol: Please let me invite you (if your ever in Central WI) for a beer or two or ten! :) Your help has been awesome! Thanks. M

Hi Def wrote:

Should I install a separate grounding bar and stake specifically for my studio electrics?

Exactly. However keep this in mind when you screw that ground bar to your panel... It will be in electircal contact with the other grounding bar. Best bet will be to do as Rod G says which is to run those (studio electrics) ground wires to a separate box (they usually are pretty cheap 30 bucks or so) and ground them all there and connect that to the outdoor earth grounding rod.

Awesome - I think I got it now! Off to Home Depot to get the supplies! Once again, Bryan, Thank you for all of your help. This board and the people here are a tremendous help. All the best, M

I am not trying to be double trouble, but I read through the other forum posting and all of the info here. Bryan, could put in one posting EXACTLY what should be done. I would be driving my electrician nuts and charge me more if I just handed him all these printed posts and told him to figure it out. I also want to know exactly what to do incase I need to troubleshoot or feel I can handle some of the install work. Thanks!

My Assumption (maybe from reading to fast) was that he was doing this himslef, However if he has an electrician, then all he needs to do is give the guy the star grounding diagram and tell him to isolate the studio electrics grounds from the other grounds. I actually took the electricians Test back in 94, and if you dont understand basic circuit design well you might not make it past page 1. LOL

Here's another link that briefly covered some isolated circuit info: http://johnlsayers.com/phpBB2/viewtopic.php?t=1330

You're allowed 40% fill on FMC (Flexible Metal Conduit) when pulling more than two wires - the tables and rules involved are so lengthy that I don't want to post half of the NEC here so people can figure this out - if anyone has a specific case, please post your wire size and type, total # of conductors, and conduit type (FMC, EMT, Rigid, etc) and I'll look up all the relevant tables and calculate conduit size for you... Steve

Can I throw in 2 cents. I wont try to 'one up' any of your advice, but being an electrical contractor and reading these posts, I'd like to point out one area of concern that may be misunderstood... A ground's first concern is safety. Any grounded parts (metal bodies.. intermal, external, etc) must be grounded so when electrified by mistake or wiring failure, an overcurrent device(breaker) will trip. First and main objective. Metal conduit is a perfect way to run circuits, and as far as I know the NEC and most city jurisdictions allow the conduit to act as the ground. And like posted before, a simple ground screw in the back of any metal box can have a lead attached and hooked to an outlet. There is your ground. The nice thing about conduit is you can pull another ground,(usually a green piece of THHN insulated wire) and have it totally isolated from the ground that is supplied by the conduit. Run it back to the service panel and its isolated. Whala- an isolated ground. This is harder to do with romex, as your cable has one ground wire and cannot be isolated if it is used to ground any metal bodies like metal boxes, so a separate piece of green wire must be ran and isolated. I have no valid input on how to do this best to reduce ground loop and such. not my area. BUT...... The area of concern is this... you can not install a ground rod only on an equipment ground and have a safe means to properly "Ground" anything. a ground rod is supplimentary and is added to a grounding system. Again, the best way design a ground rod into a system for recording is not yet my area, but I wanted to make sure that noone just hooks up a ground rod and nothing else and figures that would trip a breaker in the event of a fault in the circuit.

Here's a link that describes some of the theory behind STAR GROUNDING. http://svconline.com/news/avinstall_tec ... index.html And some more interesting info on grounding... http://www.engineeringharmonics.com/papers/s_vc.htm

In reference to Big daddyd's comments..... This is specifically why I recommend a seprate breaker panel JUST for your Studio Electronics. Most, if not all utilities will run you a separate meter for this purpose (and of course bill you accordingly. :) ) And to add this one little detail that Aaron so graciously provided for us. :) The entire technical ground systems of conductors and ground busses is insulated and isolated from all other systems with the exception of a single point at the centre of the ground system that must be, by electrical code requirements, connected to the other grounding systems within a facility. Just make sure this one minor detail is properly observed.

And if you really got the budget, and want to have good isolation, then we can venture into the world of BALANCED power. :D

Bigdaddy brings up a point that may have gotten lost - a star ground system is NOT designed to BYPASS any electrical code that is meant to provide SAFETY - only to SUPPLEMENT a standard install in such a way as to make sure there is only ONE common ground point for equipment, not a DIFFERENT ground point. The code does indeed state that metal boxes will be grounded and bonded, and this is a safety concern. If a hot wire somehow either melts or gets skinned, etc, and contacts the metal parts that humans can touch, if that metal part isn't already grounded this could become a LETHAL situation. Grounding of all metal parts ensures that if the above happens, then overcurrent protection (fuses or breakers) will operate, removing the danger and alerting us to the fact that there's a PROBLEM. For safety, this is fine - for QUIET electronics, it isn't enough. If equipment gets its ground from different points along the same grounding conductor, and ANY small amount of current is allowed to flow in that conductor, there will be a voltage drop (albiet small) - any difference in voltage will cause a current flow, and now we have noise induced into anything that's handy. To avoid this possibility WITHOUT voiding the safety aspect, the ground that each piece of gear sees must be at exactly the same potential as the ground for every OTHER piece of gear; otherwise, when we hook grounded shielded audio cables between gear we now have a LOOP which makes current flow possible between units, hence NOISE. The way we satisfy BOTH safety and quiet power is relatively simple, although anyone reading the code book for the first 2000 times could argue otherwise :? - we first satisfy safety - all metal parts of the wiring system grounded to the main system ground. Period. For a system using METAL conduit and metal boxes, this presents a problem for technical power grounding - standard electrical outlets have their metal parts which screw into the metal box BONDED to the ground pin in the outlet - so any gear plugged into this outlet would have its ground/chassis grounded to the system ground. If each receptacle gets its ground from the common ground system, and also has its cabling grounded to other chassis, there is the potential for a LOOP, which means current can flow, which means NOISE. To get away from this, and still satisfy safety, we need to make sure each piece of gear has a solid ground that is at the exact same potential as every OTHER piece of gear. This means NO LOOPS, and can only be done by running each piece of gear's ground from a common point, with no chance of a loop. If using metal conduit and boxes LEGALLY, this system requires that there be no bonding of ground within the receptacle, but WITHOUT eliminating the safety of EVERYTHING being grounded. This is accomplished by using IGR's, or Isolated Ground Receptacles - Under this method, safety ground of the wiring system itself is done in normal fashion - but the safety ground for the GEAR is ONLY connected through the ground pin of the receptacle, which is ONLY connected to the COMMON STAR GROUND - this way, each piece of gear's chassis is tied to the EXACT SAME POTENTIAL so there is no chance of current flowing in the ground. To continue this "quiet quest" to completion, you should also NOT use metal racks unless using individual ground isolator tabs on each piece of rack mounted gear - optionally, use wood racks and rails, preferably with threaded metal inserts for durability. This keeps individual rack pieces from forming their own ground loop. With all that out of the way, I'll try to write one paragraph that applies to each wiring method - ALL METAL SYSTEM - If using metal conduit and metal boxes, the receptacles MUST be of the IGR type. Mount the receptacles in the boxes normally, the conduit will be bonded to the boxes, this entire system will be bonded to the building ground, and this completes the safety ground to code. Since this is a conduit system, you'll be using separate wires and NOT romex - the STAR ground part now needs a separate (green) INSULATED wire that runs ONLY from the ground lug on each receptacle, back to the STAR point, which must be bonded to building ground. If you have 15 duplex outlets in this system, EACH outlet must have its own separate insulated green wire that ONLY connects to the outlet's ground terminal at one end, and directly to the STAR point at the other end. Now, when you plug a piece of gear into the wall, its chassis is connected directly to the STAR point, which is at building ground potential, but does NOT have any possibility of a LOOP - therefore, every piece of rack gear is at the same potential so when you connect audio cables there will be no current flowing in the ground. ADDED STIPULATION - code requires ALL conductors (including all grounds) to be in the same conduit for a given supply, because the mutual inductance of the wires is part of what trips safety equipment (breakers) in the event of a ground fault. METAL BOXES, WIRED WITH ROMEX - This presents a slightly different problem - now, we have metal boxes (which must be grounded for safety, same as above) but no conduit to ground them to. For this sytem, we STILL need the IGR outlets to accomplish a STAR system - each metal box will use the ground wire included in the ROMEX for its safety ground - this wire is bare, and will be connected to the box at one end and to the ground buss in the panel at the other end; daisy-chaining these box grounds is fine, because they are NOT part of the STAR system. To provide the STAR system, we must connect each receptacle's ISOLATED ground lug through an INSULATED ground wire back to ONLY the common STAR point. Now comes the "glitch" - because of the code requirement that ALL wires for a circuit be run in close proximity (I'm still looking for the exact wording of this, but it IS part of the code) this means you can't run the separate STAR ground wires just anywhere - they must be close to, and parallel to, the current carrying conductors of the romex. Our bud in Colorado ran into this, and satisfied the inspector by using FMC run through the same holes in studs as the romex, with all STAR ground wires in the FMC. Finally, if receptacle boxes are PLASTIC, and we're using ROMEX, the ONLY change is that IGR's are not necessary - because the boxes are plastic, there is no grounding requirement for the boxes. This leaves TWO possibilities for wiring - one is to do a "home run" for each and every outlet, each receptacle gets its own romex. The ground connects to the frame of the receptacle, you make sure a second receptacle in the box doesn't touch its neighbor, and the romex ground ONLY connects to the receptacle ground at the box and to the STAR point (which is bonded to system ground) at the panel. The second way would allow daisy-chaining of the romex conductors between plastic outlet boxes, EXCEPT that it would require a SEPARATE, INSULATED, ground wire to be run from each receptacle in each box straight to the STAR point; still no IGR's required as long as multiple receptacles in a box do NOT TOUCH each other. This isn't hard to do, just a caution that it's necessary. The downside of this is the hassle of having to run all the romex runs in the same set of holes through studs, PLUS that pesky FMC full of separate, INSULATED, star ground wires. This is why the simplest (maybe not quite the cheapest) way for star grounding with plastic boxes is the first one. Electrically, the graphic posted by Bryan is the one to go by - hopefully my long-winded explanation above will help figure out HOW you can accomplish this, and it's all in one place - if more gets added that I may have omitted, I can edit this post to include it - eventually, we can add it to the stickies here so it's easier to locate... Steve PS - when I finally find the code language for the "proximity of ground conductors" thing, I'll add that too -