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PostPosted: Wed Aug 14, 2013 4:24 am 
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Greetings again!
I posted a question years ago concerning the correct connections for wiring a switch to an Isolated Ground receptacle. Steve ("Knightfly") responded here...

viewtopic.php?f=16&t=10070

Below is a modified version of the picture in the afformentioned post.

I have a question...

Since the wiring will run to the switch first would it cause a problem with "pigtailing" the conductors for the Isolated Ground as per the drawing? (Initially, I was going to run them direct from a specific panel I had installed for the Isolated Ground wiring (as illustrated in Rod's book) with no broken connections anywhere along the IG conductor path to the receptacle. If I WASN'T using a switch for the IG receptacles, the IG conductor path can be unbroken, but if I use a switch, it "appears" I will have to pigtail since new wiring will enter the switch box connecting the switch to the receptacle)

Now, as I've said before, I'm NO electrician, and I would "think" this wouldn't be a problem, but ya just never know... :wink:


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PostPosted: Wed Aug 14, 2013 7:47 am 
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You only have one circuit, so you only have one Isolated Ground (IG).

You can never ever have a switch in any safety ground (EGC) wire.

In an Isolated Ground (IG) circuit, you want the Hot, Neutral & IG wires to have a one to one to one relationship, all in close proximity to each other, all the way from the source breaker box to the first junction box. Then each run from this junction box to it's outlet box should follow this same rule.

If you have more IG wires than Hot or Neutral wires (at any place in the run) you did it wrong.
If an IG wire follows a different route than the Hot & Neutral wires, you did it wrong.


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PostPosted: Wed Aug 14, 2013 11:45 am 
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Hey Speedskater...
I must be missing something somewhere...help me out...
Quote:
You only have one circuit, so you only have one Isolated Ground (IG).

Are you saying that each circuit can have only 1 Isolated Ground connection?
From my reading, you can connect more than 1 receptacle on a circuit/breaker, but each IG receptacle must have a home run back to the Isolated Ground buss bar. If you check Rod's book (p.105), he shows multiple IG receptacles connected to 1 breaker with each IG receptacle having it's own IG "home run" back to an IG panel box

Quote:
You can never ever have a switch in any safety ground (EGC) wire.

I have no clue what this is about...Never heard of EGC...(EGC=Electrical Grounding Conductor)
Are you saying the switch box should not have a safety ground bonded to it?

Quote:
In an Isolated Ground (IG) circuit, you want the Hot, Neutral & IG wires to have a one to one to one relationship, all in close proximity to each other, all the way from the source breaker box to the first junction box. Then each run from this junction box to it's outlet box should follow this same rule.

The modified drawing shows all 5 conductors running together into the light switch box then to the receptacle box

Quote:
If you have more IG wires than Hot or Neutral wires (at any place in the run) you did it wrong.

If I have 2 (dual) receptacles in the same metal box (a 2 gang box), are you saying I shouldn't have 2 IG conductors running into the box with the other conductors?...What would be the conclusion about running 12/4 Romex with ground if you used two of the conductors for Isolated Ground in 2 dual IG receptacles? I have one connection planned that has 6 total conductors running to the receptacle area...hot, common and safety ground to be daisy chained to 3 dual IG receptacles with 3 Isolated Ground conductors running with the other conductors (for a total of 6 conductors). If all 3 dual receptacles are in a 3 gang metal box are you saying it's wrong to run the 3 IG conductors because they outnumber the hot and neutral conductors? And also, what would be the conclusion of Rod's example on p.105?

Quote:
If an IG wire follows a different route than the Hot & Neutral wires, you did it wrong.

In the modified drawing above, are you saying the IG wiring doesn't follow the same path?

The modified drawing is suppose to show 5 conductor wiring running into a light swtch (all 5), then to a 2 gang metal receptacle box. What I wasn't sure of was if the box needed just 1 safety ground or 2 (because of 2 dual receptacles in it).
I figure "it's possible" it may only need 1 safety ground because both yokes on the receptacles are bonded to the metal box which would be bonded to safety ground.

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PostPosted: Wed Aug 14, 2013 12:09 pm 
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Just got back from 'speedskating' and now all these questions.

But it's obvious form the questions that I wasn't very clear.

So I'll try again tomorrow.


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PostPosted: Wed Aug 14, 2013 12:22 pm 
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Location: Cleveland, Ohio, USA
Well I found a minute.

Quick question - are you using EMT (metal conduit) or a flexible metal conduit?

********************
If you don't know what a 'EGC' or a 'GEC' is or the differences between them please get an electrician to do the work.
*******************

At the end of the job the total length of all the Hot wires, all the Neutral wires and all the Isolated Ground wires should all be exactly the same.
The total length of wire will be a lot less than you thought.


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PostPosted: Wed Aug 14, 2013 12:43 pm 
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Quote:
Are you saying the switch box should not have a safety ground bonded to it?
No. He's saying that you cannot have a switch in any ground wire. The ground must be a continuous path, always: no switches that can disconnect or "raise" or "lift" the ground. Your diagram mentions "switched IG", but the point is you cannot switch the IG itself. You can switch the live conductor (if code allows), but you cannot switch the ground.

Quote:
The modified drawing shows all 5 conductors running together into the light switch box then to the receptacle box.
In some countries, that would be a code violation, as you cannot mix lighting and outlets through the same conduit or same boxes. So running your outlet wiring through the same box as a light switch would not be allowed.

Also, why five conductors? You only need live ("hot"), neutral, and ground. Or maybe 4 if you run both safety ground and IG. I don't get what the 5th one is for.

Quote:
From my reading, you can connect more than 1 receptacle on a circuit/breaker,
Yes, that is allowable where I live. Not sure about the USA. But it is allowable to have multiple outlets on one breaker, provided that the total load does not exceed the wiring rating, and the breaker rating does not exceed the wiring rating. But if you do that, then you need to run all three wires from the panel to each receptacle: one live, one neutral and one ground, run right next to each other, from the panel to each receptacle. Maybe the USA is different, but that's code where I live.

Quote:
If I have 2 (dual) receptacles in the same metal box (a 2 gang box), are you saying I shouldn't have 2 IG conductors running into the box with the other conductors?...
No. If you have a dual outlet, then you have one single set of three wires running back to the panel from that box, and they are bridged internally, within the box, between the two receptacles. Once again, that's for where I live, but I'm pretty sure the USA is the same in that aspect.

But listen to Speedskater here more than to me: he knows USA code, and I only know Australian, South African and Chilean code, which are different from the USA in some aspects.

- Stuart -

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PostPosted: Thu Aug 15, 2013 3:26 am 
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Great that I have the rest of the week off which gives me time to respond...

Ok Speedskater, let me put this out front...
I don't want to :horse: but as I've already said...

-I am NOT an electrician...(isn't it obvious man?)
-I WILL NOT be hooking anything up! To save $$$, all I was going to do was run the wiring through studs etc from one point to
another and just leave it "hangin there". My plan is to have an electrician to do the actual wiring connections and for consultation to tell me how to "route" my wiring per code.
-I have been BURNED by some electricians I have got estimates from/hired (Burned= workmanship/knowledge for my application)
-To "some" degree I depended on their knowledge but as I kept getting a response like "what is Star Ground", "Star Ground is only for
commercial use" and "Romex and standard receptacles is all you need" I knew "I" had to learn more about the process to attempt to
have as good a quality as I could afford, and try to save $$$ if that was possible. For me, uh, I saw this "somewhere" :wink: that sums up
how I feel about my Studio...
Quote:
I want this studio to amaze people. "That'll do" doesn't amaze people.

I want as "quiet" of a Studio as I can get. If I do all this and I still get "buzz" or "hum" in my system, so be it...BUT I don't want to look back and say I "shoulda" done this or that...my conscious has to know "I did the best I could with what I had...
Ok, my sermon's over... :D

What am I using you ask...
The plan is to use Steel armor MC cable. With the info you've sent me, I'm considering NM cable, but I'm still leaning towards MC right now. Tell me what you think is better...NM cable or twisted conductor MC cable in steel flexible conduit. I called 3 MC cable manufacturers and here's what they told me...

My question: "are the thhn conductors in the MC cable armor twisted"...AFC manufacturer said yes, Southwire Mfg. never got back to me and Encore Mfg. said yes, but not tightly.

According to the info you sent me, the twisting is very important in the area of magnetic induction. Now for ME, it comes to this...
I only need a coil of about 250ft. If the "twisted conductor" MC's performance is better than NM cable, and the price difference won't set my pockets on fire, I'm going for that. If it DOES set my pockets to smokin', then Romex NM all the way baybeeeeeeeeeeeeeee!
According to the "Overview of Audio System Grounding & Interfacing" info you sent me, even aluminum MC is better than Romex NM cable (p.35) but I gotta use my "lovely" disclaimer..."as far as I understand"...

Ok, anyway, FROM WHAT I UNDERSTAND, MC cable or cable in conduit IS a bad choice IF the cable is LOOSELY laid in the armor. From my reading, the steel armor is slightly better than aluminum for flexible conduit. From my reading, MC cable would be one of the better choices IF the conductors are twisted/tightly twisted inside the armor.

Ok...if all or some of this is wrong, set me straight... (if I'm thinkin' like cockeyed Joe...)

Soundman2020...
I'll make these quick and to the point...
Take a look at this video and tell me how the diagram is wrong compared to how he does it...
http://www.youtube.com/watch?v=6buad3pMg5Y
(I'm not getting what you said about how the switch (in the diagram) disconnects, raises or lifts the ground. When I say "switched" IG receptacles all I'm saying is a switch will turn the receptacles off and on)

Quote:
Also, why five conductors?

The 5 conductors...
1. Hot
2. Neutral
3. Safety Ground
4. Isolated Ground for the 1st dual IG receptacle
5. Isolated Ground for the 2nd dual IG receptacle

All my reading has stated EVERY RECEPTACLE should have it's OWN Isolated Ground wire running back to a single IG point. I can't remember where I saw it on this site that says you SHOULD NOT daisy chain the IG conductor from receptacle to receptacle so having 1 IG conductor for 2 IG dual receptacles wouldn't work. Remember what I stated in my previous post...
"The modified drawing is suppose to show 5 conductor wiring running into a light switch (all 5), then to a 2 gang metal receptacle box. What I wasn't sure of was if the box needed just 1 safety ground or 2 (because of 2 dual receptacles in it)." According to code, all the wiring is suppose to run in close proximity to each other. How can I do this if they all don't run thru the light switch box?

(By the way, I haven't done any electrical work other than having a sub panel installed and a separate panel for the IG conductors to run to (My star point). I'm asking questions now BEFORE I begin any actual work)

Ok, this is my thing...
IF, IF all goes according to plan, I want to do a thread. Some stuff I've already done may be incorrect. Why? 2005, that's why.
I came on here in 2005 asking a bunch of questions etc etc. Some of the techniques may have changed since then, so what I've already done might be "old hat" by now. (er, I'm saying it may be outdated). In my thread I want to state what I did and why, what I used to do it and if I could do it again I would...??? My mistakes = somebody else's NON-mistakes...(well, it should).
What am I getting at? Somewhere, over the rainbow, somebody...somebody on this site will want to hook up a switch to an outlet. Hopefully this thread will point them in the right direction after the "fog" clears on exactly HOW to do it. As far as MC cable vs Romex, I'd like for those interested to just know there's a choice. "IF" the MC twisted cable performs better than Romex, or vice versa why? I'll tell ya what it cost me..."no shame in my game" to do that. THEN take the data and price and Ba-Bing...make your choice.
Ok fellas...I se ya'll lookin' at me like :roll: , so I'm OUTTAHERE!!!

As Roy Rogers would say, "until we meet again"...

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PostPosted: Thu Aug 15, 2013 5:44 am 
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Sorry about the EGC/GEC statement but I thought that it was a DIY project. In a similar vain, I was reading about a electrician who was doing a new retail install. The chain's IT manager spec's a Isolated Ground circuit for the computer's and cash register's. It was obvious to the electrician that the IT guy didn't know anything about electric wiring. So the electrician just installed IG receptacle's, with no extra wires, and pocketed the difference.

Some recent Bill Whitlock papers show that Romex®(NM) is a better way to go for audio circuits than EMT metal conduit.

But back to IG circuits, some metal conduit's like EMT do not require a separate Safety Ground wire as the conduit acts as the EGC.

OK, with some flexible conduit's. A section of this flexible conduit that is for one IG circuit will contain:
1 Hot wire
1 Neutral wire
1 Isolated Ground wire
1 EGC wire


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PostPosted: Thu Aug 15, 2013 5:57 am 
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Isolated Ground wiring is only useful in buildings that have metal conduits or metal building framing or a situation where metal electrical boxes come in contact with metal grounding components.

By the way, in NEC talk, grounding and grounded have very different meanings.
'grounding' refers to the Safety Grounds EGC
'grounded' refers to a current carrying conductor, the Neutral

The reason for using an IC circuit in your A/V system is to prevent or circuits interference, leakage currents, ground currents and lost neutral currents from using your cables to return to their sources.


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PostPosted: Thu Aug 15, 2013 6:39 am 
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Getting back to your switch circuit schematic. Assuming that the outlet boxes are of metal or plastic on wooden wall frames or plastic on metal wall frames. Also assuming the 2 dual receptacles are near each other.

A two conductor + ground Romex® from the breaker box to the switch box.
Hot
Neutral
Ground

A three conductor + ground Romex® from the switch box to the outlet box with the split.
Hot #1 always on
Hot #2 switched
Neutral
Ground

A two conductor + ground Romex® from the first outlet box to the second..
Hot #1
Neutral
Ground

At the first outlet box connect together:
the two Hot #1's and a pigtail
the two Neutral's and a pigtail
the two grounds and a pigtail

In the first outlet box connect:
Hot #2 to it's receptacle
Hot pigtail to it's receptacle
Neutral pigtail to the receptacle
Ground pigtail to the receptacle

At the second outlet box connect:
The Hot #1 wire to the receptacle
The Neutral wire to the receptacle
The Ground wire to the receptacle


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PostPosted: Thu Aug 15, 2013 9:39 pm 
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Ok...I gotcha!
I'll save/print out this info for the electrician once he starts wiring everything...I'll be able to double-check what he did with the directions you gave...
THANX!!

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PostPosted: Fri Aug 16, 2013 6:19 am 
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Just a little info with "real-light" ramblin'... 8)

Speedskater...is the chart at the very bottom of this post what you used to base this statement on...
Quote:
Some recent Bill Whitlock papers show that Romex®(NM) is a better way to go for audio circuits than EMT metal conduit.

(By the way, in the event that it's against the rules to post the chart below, let me know and I will remove it)

If it's NOT what you used to base the statement on, THEN DISREGARD EVERYTHING BELOW and let me know where the info is located in the "Overview of Audio..." article. I looked, but I never saw anything that specifically said the Romex was better. What I'm NOT sure about is what "Ref" and "Ref in conduit" is on the chart. I Googled it but didn't really find anything.

If it IS what you based it on, it looks like the Aluminum MC performed somewhat better than the Romex NM cable. I was looking to get TWISTED PAIR conductors in steel flexible conduit but all I saw it in was "Fire Alarm" cable at Southwire and AFC. As I stated before the rep at AFC Cable told me the conductors in MC cable were twisted...how many twists for the AFC McTuff listed below I don't know right now. (I called AFC cable about this, but they haven't got back to me yet). I did find that the Fire Alarm MC cable for 12/2 conductors had 4 twists per foot. What does 4 twists /ft mean as far as performance? I have NO clue, but I figure if it's something as important as "Fire Alarm" cable it must be pretty good as far as performance...ANYWAY, neither AFC or Southwire had 12/4 (4 conductor and 1 ground) MC cable in the TWISTED PAIR...they had 12/2, but not 12/4. And when I got an idea of the price...
:shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock: :shock:

In any case, here's a quick comparison of price for 250ft of 12/4 Romex NM and AFC McTuff Lightweight MC cable with STEEL armor (Steel is spose' (uh, I mean, suppose) to be a little better than aluminum armor from my reading...)

250ft Romex HERE...
http://www.mscdirect.com/product/731262 ... 6=nv&025=c
Price: $328.16

250ft Romex HERE...
http://www.elliottelectric.com/Products ... X124WG1000
Price: .90/ft x 250ft = $225.00

250ft AFC McTuff Lightweight MC cable (Steel armor) HERE...
https://www.platt.com/platt-electric-su ... zpid=65342
Price: $1.31/ft x 250ft = $327.50

ALSO...for those (like me) that like VISUALLY seeing how things look/work, the picture below is one I found that shows the wiring of a switch and receptacle WITH POWER COMING IN AT THE RECEPTACLE FIRST AND USING PLASTIC BOXES...Note that THESE ARE NOT ISOLATED GROUND RECEPTACLES.

My vacation is about up, and I'm still tryin' to decide on Romex or MC...
The answer to this reply will "seal the deal" for me...


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PostPosted: Sat Aug 17, 2013 2:27 am 
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Ok,
(ok...ok...ok...)
Man, I hear an echo in here...check, check 1, check 2...hmmmmm...oh well...

Anyway, an update...
Southwire engineering called me back and stated their wire is twisted. He said it's twisted clockwise so many feet then counterclockwise so many feet.

AFC engineering called me and calculated their "conductor twist" in MC cable is twisted 2.3 to 2.4 times per foot.

So, all 3 cable manufacturers (AFC, Southwire and Encore) stated they do twist their wire in the MC armor. This MAY have something to do with why the Aluminum MC produced the 2nd best results in the test Bill Whitlock conducted.

I will say, in looking at the test and how it was done, they only used 3 conductors (wire) per "cable" type. I don't know if more conductors (wires) would change the results or not because of factors (due to additional conductors and their positions) as he stated on p.31.

BUT...for now, (to me that is...) if you take what he says and his test results, twisted load and neutral is best, (which I was only able to find in Fire Alarm cable for MC type cables. The load and neutral are twisted.) followed by Aluminum MC next.

If ya'll have other info that can help re-direct me if I'm WAY OFF BASE...help the ol' man out now!"

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