Hi guys,

Thanks so much for all the replies on my first thread. I decided to refresh this thread with a new question.

Based on your comments, I decided to run 20A dedicated branch circuits to my studio. Keeping computer/peripherals on one circuit and my outboard audio gear on another one. I also decided to run isolated ground circuits.

Question:

Would I benefit from using 10/3 wire over 12/3?

It seems like a heavier gauge wire would result in more consistent supply and lower impedance (but I really don't know why . . . that's why I'm asking you guys!)

The next problem is that if 10/3 would be beneficial, where can I find a 20A breaker that will accept the bigger wire. The Cuttler breakers I saw at HD today were for 14 or 12 gauge.

Any thoughts?

Thanks again,
Mike

As a rule the larger the gage of wire the less the resistance/ft. SO while 10-3 will have some benifit the difference will be too small to matter. Also most breakers will accept #10.

Thanks nesparky!

"I decided to run 20A dedicated branch circuits to my studio... using 10/3 wire"

Wouldn't using 10/3 [or 12/3] to create two circuits create 'shared' circuits, not dedicated circuits?

Wouldn't the sharing of the neutral between circuits undo much of the isolation you are trying to create for this sound system?

Dana, If he is running a 10-3 or 12-3 he is technically only running one circuit right?

Seriously, I do agree with Dana on this. You should not run multi-wire circuits for audio equipment. You should run two 10-2 or 12-2 cables. All current design 15 and 20 amp breakers will accept #10 wire. I hope your planning on getting an electrician to help you with this project. Installing new circuits is not a DIY project.

Curt

I also see no reason to run these circuits with an isolated ground especially if they are originating at the service panel. If you mount your receptacle in a plastic box the only thing your going to be isolating the ground from is the plate screw. In commercial work we use isolated ground receptacles because we are running the branch circuits in metal raceways or with metal cables but since your using type NM cable your ground is already isolated.

Curt

To clarify . . . each receptacle will have it's own circuit. I was just trying to find out whether to use 10/3 or 12/3.

Caselec . . . if all anyone needed to achieve an "isolated" ground was just a dedicated circuit and a receptacle, then why do people even bother w/ a true Isolated Ground receptacle. I've been following a Black & Decker book for home wiring that suggests IG circuits for computers and sensative electronic equipment . . . it says IG circuits "provide extra protection against power surges that can hram equipment." Also, every studio I've been in has them.

So are you saying that connecting the bare wire of 12/2 cable to the grounding screw of a receptacle mounted in a plastic box offers precisely the same protection a 10/3 IG circuit?

They would perform precisely the same?

As far as hiring an electrician, I may hire one . . . I spent $300 a year ago having an electrician install 3 dedicated circuits in my other house for my audio. It seemed like alot of money, but I wanted it "done right." About a week later I flipped on a light switch and noticed a pop in my speakers (which were powered by one of his dedicated circuits). So I spent all that money for good expertise to achieve isolation and I didn't end up getting any. So that is one of the reasons I am on this forum . . . to learn how to do it right. And there seems to be more than one way to do it.

After reading the B & D book, installing a new breaker and pulling cable for a circuit seems to be within the capability of a prudent home owner (at least the book says so).

If I do the work myself, rest assured it will be thoroughly researched . . . I won't do anything I don't think is within my abilities.

Thanks,
Mike

I have recently completed a recording studio in my basement. We have digital equipment recording equipment that's well internally grounded and balanced input and output jacks to prevent static and noise. We went over which would be the best and safeset way to power all the equipment. We ran dedicated 20 amp ckts using normal 12/2 romex. Bought a power conditioner for spikes and noise. Everything is running clean. The niose and hum we experienced is looping through solid state amps which have preset gains and overdrives. That is just a matter of readjustments. All of our input extensions are run in sheilded cable. Learning to run all this digital equpment is definately a challange but that's another story.

~Ange

Thanks Wirenutt . . . my studio is digital too so I will take note of your suggestions.

Thanks,
mike

How does this work. The only difference between the IG and a standard circuit is the loction of the EGC termination. In a building with only one panel, even that is not different. There is no way that an IG circuit has any effect on "power surges". It may be able to reduce some of the "noise" on the EGC, but that is all it can do.
Don

[This message has been edited by resqcapt19 (edited 05-06-2003).]

In my humble oppinion running an isolated ground is what your going to have if you use dedicated circuits. Also when counting conductors you don't include the ground wire (grounding conductor), so 10/2 is a hot, a neutral (grounded conductor) and a ground. 10/3 would be 2 hots a neutral and a ground and using this for 120 volt circuits would be considered a multiwire circuit, and if you lose a neutral you will have 240v and smoke any piece of equipment on that circuit. So if you are truly using 10/3 you might re-consider.

A dedicated IG circuit in a residance is a complete waste of money. You are running NM to a plastic box mounted on a wooden framing member. This makes it an IG circuit already. The only time an IG circuit would be used is if the circuit were ran in a metalic raceway fastened to concrete or structural building steel. Just run a dedicated circuit to get the same benefit.

The best setup for a basement recording studio would be to run a dedicated 240 volt 30 amp circuit to a balanced power transformer with built in distribution. There are several out on the market. Best ones are made by Equi-Tech (http://www.equitech.com/). They will eliminate any ground loop problems on unbalanced audio lines, and have filters built in.

In my opinion I would run dedicated 20 amp circuits using 12-2 nm, don't bother with the 10 its not worth the trouble. Then depending on the actual load, a small UPS(uninteruptable power supply)or series of UPS units ,like for a computer might accomplish some of the filtering you desire, They are out there for upwards of 75 to 500.I found a 1000 va with 75 minute back up for $200. You don't need the battery back up but the power conditioning will be worth the expense.




[This message has been edited by mlk682 (edited 05-08-2003).]

Hey Mike;

What kind of studio are you building, how many rooms? I built a 3 room studio. It's relatively quiet from room to room. I used a noise level meter from radio shack to check actual room variance and from the next room to see how much noise was being filtered out. We built it on a budget, I think I would have done a few things differently now to help reduce even more bleed through noise. Searching on the internet and speaking with people who have built studios gave me plenty of good ideas.

~Ange

Ange,

It is a 2 room studio (control room and live room). They aren't very big but very well designed (I hired a designer but I'm doing the work myself). As far as isolation techniques, lots of double 5/8 drywall on RC channel. I also used lead impregnated vinyl barrier in strategic places. And LOTS of acoustic caulk ($$ . . .enough to pay an electrician to wire it for me : )

I am being swayed to just run the 12/2 NM . . . but it isn't really that much more $$ to do an IG and let's face it, lots of studios have those interesting "orange" plugs that say, "I have special power."

I know if I'm running a dedicated circuit NM to a plastic box then it is IG, but I think I would feel better if I just ran the IG to spec. . . doesn't take anymore work and marginally more money.

Anyway . . . I'm really excited about the studio. The control room will rock . . . diffusors on the back wall, acoustic clouds in the ceiling, cloth lined walls with acoustic baffles in between.

. . . oh and real clean power!

I also just got a sweet A/D coverter. A disconiued model from Panasonic called the WZ-AD96. You can pick up 8 channels for $750 . . . but they are getting hard to find. If you are going digital, I highly recommend it.



Thanks,
Mike

Mike,

As myself and several others have said running 2 equipment ground wires and using IG receptacles would be useless in this application but if you would decide to do this you could not run type NM cable. They do not make any NM cable that has 2 equipment grounds so you would need to run this circuit in EMT, use MC cable that is designed for IG circuits or use HCF AC cable. Your going to be spending alot of extra money just to have a separate ground for the plate screw.

Curt

Point taken Curt . . . the information I've been reading (articles online about IG, home improvement books, I even tried to contact a few folks here off the forum to no success) has not ruled out NM for IG. In fact the Black & Decker book shows pictures of IG recptacles with 12/3 NM.

But I think I will defer to the experience of the members of this forum and run 12/2 NM to plastic boxes.

Question:

There is a segment of the run (from the wall to the studio mix desk) that will be on a concrete floor. I was planning on running that through a small piece of conduit and building a threshold to cover it.

What would an electrician do in this case?

Thanks,
Mike

Hey Mike;

I was surfin the net on what diferences there is between balanced and unbalanced wiring. The balanced has a hot a cold and a ground. You only hook up one end. It shows not to connect to grounded equipment where other equipment is grounded to it through lets say a sheild. I see that the big problem can be what they call a ground loop. Having too many grounds creates an antena. But if you hook them up right, they act as two noisey signals that run at 180 degrees appart so it cancels each others noise out. The extra ground line in a power line, I'm not sure if this would act as a drain, I think it's a good question though. My brother Sparky in VT had recently installed 12/2 M/C armored cable in a hand radio room hoping that this armor would act as a sheild against RFI. This subject gets so deep. I see you went the extra mile on your studio, nice job and good luck.

~Ange