[jarcher]

Ok folks, can appreciate this same question / request has come up before on this forum, though the last times seems to be 2011, 2007, and one older.  So thought I'd put out the question / request again to reach all & perhaps have the benefit of new members & their experiences.

I've got a dedicated line to the home theater basement, but honestly the electrician thought I was sorta crazy & I didn't ask a lot of questions or do a lot of research.  Now that I'm preparing to do the same for the living room AV system (where the "serious" 2 channel audio gear resides), wan to make sure I get it right.

For the basement basically used from front to back:

(2) Shunyata twin receptacles

(20 ft) UF-B 10AWG / 2 (I think) Romex - yeah, found out later this spec if for underground burial

(2) Square D 30A breakers

Don't know more about how he wired - presumably each receptacle got it's own hot & they shared a ground (?)

Anyway, for the living room would appreciate advice on:

(1) Outlets.  I've got a super pricey Oyaide R1 - put it in for laughs because the 50+ year old outlet was falling apart.  Obviously sounded a lot better at this super low bar. 

But I need at least one more.  Do I really need to go "high end" with the outlets? Wondering what possesed me to buy such expensive ones to begin with. Will a 20A hospital / spec grade hubbell or similar be enough?

(2) Power line. Gonna need probably 30-40 feet. Is a regular southwire brand romex cable sufficient?  I've seen on specialist sites pricey Cardas 3x10AWG in wall power cord at $12 a foot - which gets pricey fast - even if it is "oxygen free pure copper". 

Assuming regular romex, should I do with a 10AWG/2 uf-b or a 10AWG/3 nm-b type instead?  Seems like the NM-B style being oval may be easier to run, and having 4 conductors allows each outlet to have separate hot & ground leads (?)

And as for connecting - a line for each 2 plug receptacle - or do the 10/2 thing again w/ shared ground for both - or 10/3 as per above?

(3) Breakers.  The newer ones in my panel all seem to be Square D.  Any reason to change brand? Doing 30A again I can understand would be over kill.  20A enough?

Please feel free to be as detailed as you like in recommendations (e.g. model #'s and links), though my technical knowledge is limited (not an electrician nor electrical engineer).  Just want to get some feel for what's best for the $, then buy & tell the electrician what I want.

Hoping that this will be an up to date resource for any coming to AC looking to answer the same question.

Thanks!

[jarcher]

Oh - and of course you're totally free to say "buy a $1000 Pi Audio uberbuss" or "buy a $800 Environmental Potentials whole home surge protector", but would prefer comments directed more on topic towards receptacle, wire, breaker & installation. 

Not to try to "put rules" on the thread, but going towards all kinds of power protection / conditioning / regulation / etc products can sorta de-rail this.

Thanks!

[sounddog]

This is quite timely, as I also plan to put in a dedicated line when we do some remodeling in our new house next year. And the simpler the explanations, the better for those like me who are truly lacking in technical expertise!

[DaveC113]

To be code compliant you will need to use 20A breakers for 20A rated receptacles, if you use a 30A breaker you would need to fuse down to 20A to use a 20A receptacle. You can use 10g wire if you want, 12 is minimum for a 20A line. The grounds will be connected at the box, so I'm not sure separate ground wires will help, but as we know, anything can make a difference...

[cab]

a separate circuit for any digital is a good idea if appropriate. Using flexible metal conduit and grounding it helps to shield if you have a lot of signal running around the house...

[jarcher]

Using flexible metal conduit and grounding it helps to shield if you have a lot of signal running around the house...

Can you elaborate please on the benefits of flexible metal conduit & grounding it.  On one of the other threads here I had read that it is code in some states and not in others.  My electrician mentioned it once, but it seemed to be mostly useful when the wiring was going to be outside / buried / what not & needed extra protection.

As this dedicated line is going to be purely indoors, running the romex through flexible metal conduit didn't seem warranted.

[jarcher]

To be code compliant you will need to use 20A breakers for 20A rated receptacles, if you use a 30A breaker you would need to fuse down to 20A to use a 20A receptacle.

Yes - became aware after looking at these forums & then the breakers for the existing dedicated line that what was done (admittedly at my request) is not code. Seems like I should get them changed over to 20A breakers........

[srb]

For 20A circuits with 12AWG wire or larger, if the circuit contains more than one receptacle, 15A receptacles may be used and/or mixed with 20A receptacles.
 
For 30A circuits with 10AWG wire or larger, either 'NEMA 5-30R' or the 'L-5-30R Twist-Lock' version receptacles with the bent right angle neutral blade must be used.  The standard 5-15R or 5-20R receptacles with straight neutral blades cannot be used.
 
Although there is no absolute specification for maximum cable length because it depends on the number of devices on the circuit and current load, 100 ft. is a safe rule of thumb for 12/2 wire on a 20A circuit with no more than 5% voltage drop.  Beyond that length a 20A circuit might call for 10/2 cable, but in your case, if you want you can use 10/2 to insure very low voltage drop on your 20A circuit.  In small quantities, the difference between 12/2 and 10/2 NM might be $0.50/ft.
 
As far as UF vs NM cable, if you're not burying it or routing it through super high moisture areas, save your money and buy the NM.  If you have that high of moisture in your walls that you would need UF cable, getting sick from mold would be your bigger concern.

For breakers, I haven't seen any audiophile breakers (!) so you generally use the breaker for your brand of panel - Square D breakers for a Square D panel, Cutler-Hammer breakers for a Cutler-Hammer panel, etc.
 
Steve
 
 

[jarcher]

Very helpful - thanks SRB. 

Assuming use of 10AWG (why not - price is not much more than 12AWG), and regular NMB romex (haven't heard anyone justify using Cardas pricey OFC power cable), last question for me re: power cable would be:

To wire 2 receptacles would it be better to use 10AWG/2 NMB, 10AWG/3 NMB or run two separate 10AWG/2 NMB lines (one for each receptacle)? 

Sorry for the ignorance on the grounding - electrician expects me to buy the supplies & as this is kinda a "specialist" application don't know whether asking him directly is going to answer anything.

[srb]

To wire 2 receptacles would it be better to use 10AWG/2 NMB, 10AWG/3 NMB or run two separate 10AWG/2 NMB lines (one for each receptacle)?

What you are talking about is a multiwire branch circuit such as is commonly used in homes for powering separate dishwasher and disposal circuits with a shared neutral, for example.  It is required that the breakers be on opposite poles or sides of the panel so that the neutral is not overloaded.
 
As you surmise, the main reason to do this is the cost savings of the wire.  It is also sometimes a little more difficult to pull two runs of cable versus one, but usually not a huge deal.  But because this is for a sensitive audio application rather than appliances or lighting, I would just run two separate 10/2 cables as an imbalanced load can sometimes lead to electrical noise and you will also have isolated grounds for each circuit (at least back to the service or sub panel).
 
Steve

[jarcher]

Thank you so much.  Sounds like I should be un-doing some stuff on the HT basement line - i.e. for one placing the second receptacle on its own dedicated line, and reducing breakers to 20A.

So sounds to be like the conclusion is 10AWG/2 NMB romex for each receptacle, 20A breakers max, and nothing fancy / special required for romex (i.e. like the Cardas stuff), nor for the breaker (use what works for your panel).

Anyone care to sound off on receptacles?  "Audio Grade" Shunyata, Oyiade, Furutech, etc vs just a high spec Hubbell, etc?

I know the "audio grade" manufactures like to offer ones w/ different materials that are supposed to sound different, but despite buying some myself, still skeptical.  Seems just to difficult to do a/b comparisons with receptacles so not many have bothered. 

I will give it a try now as I have the Oyiade R1 from before - one of the "top rated" darlings - vs mostly likely anything that is less expensive.

[lokie]

I was given this advice from the design engineer of a well known Audiophile Power Conditioner manufacturer.

"Use round Romex 10/3 or 12/3. Inside are 4 wires,  a black, white, red and bare wire(s). Use black for hot, white for neutral,  the red and the bare are both for ground (using 2 wires for ground gives you a much lower impedance path to earth ground resulting in a quieter system with a lower noise floor). If you do 2 dedicated circuits, make the wire length identical for both if at all possible."

You can't have too many dedicated lines as long  as your panel has the slots. The biggest expense is the time of the electrician, so, if he's putting in two lines then putting in 3 lines isn't that much more of an expense. At least get a price for the difference,

i have three different outlets ranging in price from $15 to $250. To be honest, I don't have the patience to hunker down and "AB"  the different outlets but, I can tell you that I haven't realized any revelations. All my kit has substantial power supply's and transformers, so maybe i don't realize the gain from the expensive outlets. 

You would probably be fine with the well known Audiophile approved Pass & Seymore's and Hubbells but if you want to play it "safe" and step up a notch then maybe go with  a Porter Port (which is a modified Hubbell).

[cab]

Can you elaborate please on the benefits of flexible metal conduit & grounding it.  On one of the other threads here I had read that it is code in some states and not in others.  My electrician mentioned it once, but it seemed to be mostly useful when the wiring was going to be outside / buried / what not & needed extra protection.

As this dedicated line is going to be purely indoors, running the romex through flexible metal conduit didn't seem warranted.

It acts as a shield from emi, rfi......regular romex is not shielded.

[Speedskater]

While Steve & lokie covered a lot of territory, let me add just a sit:

a]  Romex® is a brand of the Southwire Co. everyone else makes "NM" non-metallic.
b]  "UF" cable is very similar to "NM" cable, but it's rated for underground and wet locations.
c]   10AWG/2 means that the cable has a Hot(black) a Neutral(white) and a Safety Ground(green)wire.
d]   10AWG/3 means that the cable has two Hot(black) & Hot(red) a Neutral(white) and a Safety Ground(green)wire.
e]   A virtue of using 10AWG/3 in a 120V circuit, is that the cable has a natural twist which reduces interference transmission.
f]   The idea of putting digital devices on a separate power circuit has been overtaken by events.
g]  With the exception of large power amps and projection TV's,  current thinking is to put all equipment at one location on one circuit. The idea is to reduce the length of power cables from unit to unit.
h]  Metal conduit (or tube) will reduce the radiation field.  But thought-full placement can make it unnecessary.
i]   For audio purposes the ground connections unit to unit and to Neutral are more important than the connection to Mother Earth.  The connection to Mother Earth is for safety!

[rw@cn]

f]   The idea of putting digital devices on a separate power circuit has been overtaken by events.

Interesting. Could you please provide a few links so that I can read more about this?

Thanks

[Speedskater]

http://www.audiosystemsgroup.com/publish.htm

Start with the "Power Systems" and "Grounding" Power Point slides.  But making sense of PP is not an easy task.

Time and again, I read about putting all the units on one circuit.
The lines a blurry between digital and analog, between traditional (linear) and SMPS power supplies in equipment.

All 50 of Jim Browns papers are well worth reading, even the ones that seem to be about HAM radio.

[rw@cn]

Thanks.

[jarcher]

Thanks speedskater. 

So, sorry if this seems repetitive, but just for my own & hopefully other easy reference, summation at this point seems to be:

Wiring:
(1) 10AWG/3 RMB
(2) Grounded flexible metal conduit

Breaker:
20A max
Whatever brand your panel takes

Receptacle:
Probably not so critical, but perhaps as a "base" a 20A Pass & Seymore, Hubbell, or Porter Port

Hook up (sorry non-technical term):

(1) Dedicated line for each receptacle.  Use black for hot, white for neutral, red and bare  both for ground

(2) Preferably keep length of lines same for each receptacle at each outlet location (?) I.e if you have two receptacles at home theater basement, keep the length the same for each outlet.  If you have two receptacles at another location (e.g. living room as is my case), keep those two lines the same length. 

Not a problem for me as both receptacles at each location are or will be side by side.

(3) High current devices such as power amps, projectors, etc, on one dedicated line / circuit

(4) All others components on the second circuit / receptacle (?)

[jarcher]

If we are getting this detailed, what would be in theory "best practice" for breaker location at panel, assuming this is relevant?

E.g. avoid putting AV breakers on side w/ refrigerator / ac / furnace / or other high draw potentially "dirty" appliances?

Someone also mentioned something about phasing & location, that I admittedly didn't completely understand.

Assuming that one receptacle is dedicated to high current devices, and the other for all others, would it be best to put each breaker respectively on either side of the panel (on separate poles)? Does this matter?

Would it be possible / advisable to have a whole separate panel just dedicated to AV equipment?

Sorry for the "hyper-granularity" of these questions.  Just thought these additional kind of questions would be useful to some folks who may be working on a new house - or in case the "dedicated AV panel" is not a lunatic idea. "Audiophiles" have been known to do crazier and potentially less scientifically sound things to guarantee or improve sound .........

[dmatt]

The past power line discussion at AC has been very helpful to me.  I am in the final stages of setting up my remodeled living room for 2CH and HT.

I've run 8 20A dedicated lines. Why eight?  I'm nuts.  And since we were putting in a new floor, I could terminate some of the lines in the floor to eliminate cords in the room.  One outlet is in the floor by each of the mono amps (next to the main speakers).  One is for the subwoofer in the far corner, one in the floor for the sub in the middle of the room, one for the 2CH analog components in the rack, one for the 2CH digital (Speedskater, if only you told me earlier!) components in the rack, one for the HT components, one for the rear channel subs (in another end of the room).  All runs are less than 30 feet from the sub panel to duplex.

I took a departure from the usual romex so I could twist the hot and neutral lines myself and leave the ground a straight run.  Per the documentation you saw in the earlier threads on AC (http://www.audiocircle.com/index.php?topic=90292.20), putting twist in the hot and neutral lowers the inductance effect on the ground wire and reduces ground voltage induction.  But now it sounds like you can get the same effect by getting a certain kind of romex with twists already in it per the above post by Speedskater.  That should save you some effort.

All my dedicated lines are in steel flex conduit terminated to steel boxes.  Inside the conduit I have a twisted pair of 10AWG XHHW-2 stranded for hot and neutral, 8AWG XHHW-2 for isolated ground, 14AWG XHHW-2 for equipment ground.  I chose XHHW-2 over THHN/THHW because the insulation has a lower dialectric constant and it didn't cost more than THHN.  I had to twist the hot and neutral myself.  As others have pointed out, twisting the hot and neutral lowers the inductive effect on the ground wire.  My thought on the steel conduit was that I had to pull the XHHW anyway, I might as well put it in steel for any additional shielding (vs. aluminum conduit).

Since I am using isolated grounds, I went with Hubbell IG5362 outlets.  Without isolated grounds I would have chosen either Porter Ports or another Hubbell variant (Jena Labs has one too).  Jena Labs ordered IG5362 outlets for me and then cryo'd and tweaked them like their Jena #1 outlet.  The Hubbell extra heavy duty industrial series outlets are pretty good, I skipped the hospital grade since those are plated with nickel to avoid corrosion.  Some say the nickel plating is not as good a conductor as the unplated brass or phosphor bronze.

The eight lines will terminate to a SquareD sub panel with copper isolated ground bar and neutral, with bolt-in breakers -- I think all of that is just a means to ensure good conductive material in the energy path and SquareD panels are pretty well constructed.  All circuits are on the same phase (the neutral is spec'd to handle 2X the usual current since there is no phase cancellation).  The sub panel goes back to an Ultra K 8KVA isolation transformer that takes in 240V and outputs 120V with both legs on same phase.  The transformer also has triple shielding for common mode noise attenuation, a high frequency filter, and TVSS transient protection.  There is a new second ground rod (the first is at the main panel) next to the transformer.  The main panel feeds the 240V to the isolation transformer.

Probably overkill, but hey, when one has the ceilings of the 1st floor open and no floor on the second floor, why not swing for the fences.

If any of what I outlined is now the wrong approach due to the latest knowledge, please feel free to let me know.  I may not be able to change things at this point, but at least I can kick myself for making a bad decision for many years to come.  And isn't that what this hobby is sometimes about anyway?

Cheers,

David