Star Grounding System Question

[Rivernile]

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 -

Ok, Stuart read the above.
1) I am using plastic boxes with 14-2 wire(tree conductors)

2) I have a 100 amp sub panel off my main panel upstairs.

3) The electrician also ran a seperate GROUND wire and rod outside the studio in the dirt,but i noticed it is bonded to the Ground in Subpanel.

So what i did was run three circuits to control room and three circuits to the live room.
Two of the circuits in each room have 2 outlets on them.
Then i join the ground cables for the two outlets togather and then at the subpanel to the ground bar.

Is that not good ,i am still a little unclear
Thanks

[Rivernile]

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.

COULD YOU CLARIFY THIS PART FOR ME ?

I am using plastic boxes and 14-2 wire for outlets,3 cicuits each room.
One or more outlets on some circuits,how do i connect the ground for the receptacle in series?
Ihave a subpanel with ground rod outside studio -[/quote]

[Speedskater]

Ideally you only want the safety grounds from different circuits connected together at one point (the starting point). The "hot", "neutral" and "safety ground" wires should all follow the same path and be in close proximity to each other from circuit breaker box to outlets. You do not want to share neutrals or safety grounds from different circuits in your rooms.

[Aaronw]

In the plastic boxes, if you have a dual gang (putting in 2 duplex receptacles), if you wanted separate ground wires for each duplex, and not worry about having to run an additional ground wire, you can use 3 conductor + ground wire, and use the 3rd wire as a ground. Just make absolutely sure, you use green tape wrapped around that 3rd wire on both ends to identify it as a ground wire. Otherwise, it could be hazardous for you or someone going in behind your work.

[knightfly]

Current location of the old, dead grounding link referred to earlier -

http://recording.org/studio-constructio ... eight.html

Only starts as a thread on receptacle height... Steve

[Speedskater]

DO NOT ever, ever put the the Safety Ground (EGC) wire in a separate metal conduit! The Safety Ground wire should be in close proximity to the Hot and Neutral wires from the outlet all the way back to the breaker panel.

[GelderBar]

DO NOT ever, ever put the the Safety Ground (EGC) wire in a separate metal conduit! The Safety Ground wire should be in close proximity to the Hot and Neutral wires from the outlet all the way back to the breaker panel.

What happens exactly ? Does it make it sensitive to surging ? I've never tried that. I imagine it would make it very sensitive to lightning

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[Speedskater]

DO NOT ever, ever put the the Safety Ground (EGC) wire in a separate metal conduit! The Safety Ground wire should be in close proximity to the Hot and Neutral wires from the outlet all the way back to the breaker panel.

What happens exactly ? Does it make it sensitive to surging ? I've never tried that.

Three different reasons:

1] EMI/RFI noise getting into our audio equipment. This is a big point in the Middle Atlantic paper:
http://www.middleatlantic.com/power.htm
They think that the Hot and Neutral should be twisted and the Safety Ground should be in close proximity.

2] The general electrical rule that all the Hot phases, Neutrals and Safety Grounds (EGC) need to be in the same metal conduit. If not large Eddy currents build up and some times melt wires.

3] LIGHTNING. Lightning has a large high frequency component. A Safety Ground (ECG or GEC) in an improperly grounded conduit will have the conduit act as choke and develop large high frequency voltages between it and other parts of the power circuit.

[pqkawara]

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!

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?

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[Speedskater]

If a conduit is used, the ground wire (EGC or IG) the Hot and Neutral must be in it!
The Ground Rod wire enters the building at or near the Service Entrance and is connected at the main breaker panel.
All interior ground wires must be connected at this same point.
If you have a Romex (NM) or plastic conduit system you don't need a IG.
IG's are only needed in metal conduit systems where you have no control on what other grounds may touch the conduit.
Tape on bare ground wires allows you to control where the connection is made.

The Grounds and Neutrals MUST be connected together in the main panel box!!!!!!!

Go back and read the posts by "knightfly", he is very knowledgeable and put a lot of effort into getting the detals covered.

[Johnny Corvette]

If I was to wire with a home run circuit per receptacle - plastic boxes, IG receptacles and romex 12/4 - all back to the main panel, I end up with a bunch of hot and neutrals, etc to teminate. Since I would prefer them all on the same breaker what is the usual method for terminating? Do you typically add a junction box next to or near the main panel to consolidate wires before landing at the main panel breaker terminal?

A sub panel might be best option but, the main panel, access to ground bar, etc etc. is right next to studio. Just planned to add a ground terminal for IG, bond to mains ground and maybe beef up ground rod.

[Soundman2020]

The neutral wires normally go to a bus bar inside the panel, and each live wire goes to its corresponding circuit breaker. Depending on your electrical code, you may or may not be allowed to run two or more circuits from each breaker. Some places insist on one breaker per circuit, others might allow each breaker to power two circuits, or even more.

Personally, I prefer one circuit per breaker anyway, even if code allows more. Breakers aren't that expensive, and it gives you more flexibility and better safety. Also, if something does go wrong somewhere that causes a breaker to trip, you only lose whatever was on that specific circuit: everything else stays on.


- Stuart -

[Johnny Corvette]

Are you saying one breaker per receptacle? That would be a lotta breakers.

What I was saying is for example one circuit for the mix/Control room with 5 receptacles each with its own home run to the main panel. Can't terminate all those hots on one breaker.

[Speedskater]

In a system wired with Romex®(NM) and plastic outlet boxes Isolated (Insulated) Ground receptacle's are not needed nor do they serve any function. Only in systems/buildings with metal conduit or metal outlet boxes or metal building framing that the receptacles might come in contact with are IG receptacles useful.

In general on any one AC power circuit I try to reduce the length of the power cable from outlet to outlet. I would use a heavy power cable from the breaker box to a centrally located junction box and only then split the cable to the individual outlet boxes. With only one cable to each box regardless of the number of receptacles in that box.