I would run 10/2 w/ ground or run an isolated ground which is essentially an extra ground that runs along with the 10/2 w ground. 30-35 feet is nothing. You are already home running 10/2 to each duplex outlet. That's plenty of separation. Just make sure your ground is good. All this can be for naught if your house ground is inadequate. You might look into a ground rod just for the 4 runs to the system. This is where isolated ground hook up could be beneficial. Then the extra ground could go to the rod and really be effective if the rod is installed correctly.
The subpanel is great idea. Then I would run the 10/2 which will allow you to use both poles of the panel and i would also just wire each outlet as circuit. You will never overload each circuit and use a 20 amp breaker, the 30 amp might make your components absorb too much overload before it trips. You might check into the new Romex 14/4 w/ground that would give you greater skin effect than the 10/2 since you would have 2 14ga leads for each pole.
Using a sub-panel to shorten the lengths of the runs is a good idea. Be sure to use adequately sized feeders to the sub-panel. It is also true that for 10 Ga, a 35 foot run is not a big deal. However, if you use a well placed sub-panel, you will minimize costs for cabling.
Theo is right about the 30A breaker. This is, IMO, a very bad idea. Theo's suggestion about 14/4 is interesting and worthy of consideration. You might also do a review on his website the ideas that Russ Andrews recommends.
Chriskeating brings up the point of verifying your ground system. This cannot be overstated. This should be done first. See the thread http://forum.audiogon.com/cgi-bin/fr.pl?fcabl&1102789057
for a thorough discussion of grounding systems and AC issues. Seperating the ground source for the runs to the audio equipment (seperate from the house system) is a no-no according to many local codes. Yours may vary. Some seem to have done it with success. If you add ground rods and bond them together you still get much of the benefit.
Using 10/3 in the manner you described with individual hots and a shared neutral and a shared ground is also a bad idea. Sharing the ground....maybe. I would not do it, but then I may be particular. Sharing the neutral is a very bad idea as you are then placing twice the return current flow on ONE conductor AND sharing all of the noise.
The thread above talks about a lot of this in great detail.
Thanks guys. So the only reason for using 10/3 with dedicated lines would be to use the extra hot as an isolated ground. Do you use an isolated ground only in the instance where you have a sub panel needing its own grounding rod? Ideally I'd like to use the main panel's grounding system and breakers from there. How do you wire each outlet in a duplex separately so that each are dedicated. Do I need 2 runs of 10/2 to each duplex? Can I actually use 10/3 for this application? Thanks again. I am just concerned that if I am going dedicated, a CD player and processor sharing the duplex is not really dedicated. How can I separate? My plan once this is sorted out is to run an outlet box with all these duplexes(4) within it. Might do 2 separate boxes with 2 dedicated duplexes in each mounted to the floor.
Jeffcot is abslutely spot on about sizing the run to the sub panel correctly. Any potential benefit from shortening the individual runs can be lost by undersizing the feed to the panel. If you use this method, be diligent about checking polarity when you hook up your system for the first time. Don't assume that the electricial has wired everything properly.
Dave, first of all your electrician will run the wiring according to code - regardless of what you suggest to him. The only thing he'll consider is wire that is sized bigger than required that will physically fit the outlet or breaker. For example, he won't accomodate you with a 30-amp branch circuit breaker, floor outlets, 10/3 wire with common neutral or a secondary ground. All are no-no's with respect to NEC and most local codes - he'll explain why.
If you want an isolated ground, ask for "hospital grade" wiring, aka "Type MC" cable. This aluminum-armored cable comes with the extra green wire, that is 10/2 MC will have a black white AND green whereas 10/2 "regular" (or BX) will only have black and white. Regular BX 10/3 will have black, white and red - no green. Can't use RED for ground with most codes. If you're using Romex, then the green comes with the wire - that is, 10/2 romex has black, white and green.
The use of 10/3 wire is intended to be used in switched outlets where you want to continue the circuit power independent of the switch to the next outlet. Commonly used at receptacles that are switched on by a light switch and ceiling fans with separate motor and light control. Sometimes it's used by stingy homeowners to run two circuits with one neutral - saves a run of cable.
Installing a sub-panel is a very good idea if you can swing the cost. Your electrician will be able to recommend the correct size for your application. I would overkill the wiring to the subpanel by sizing them according the the panel rating. E.g., if it's a 100-amp subpanel run three #3 wires in 3/4-inch EMT, if it's a 60-amp subpanel, run three #6 in 1/2-inch EMT. Again, trust a competent electrician above all else.
Gs5556 is both knowledgeable and thorough. Listen to what he is saying.
I know it has been mentioned before, but, be sure to ask your electrician to check it carefully. The importance of a bullet-proof grounding system cannot be overstated.
If you are concerned about isolation, ask the electrician to install dedidated isolated ground circuits. The definition is in the thread I referenced earlier. These circuits will use 10/3.
If you want maximum digital isolation, simply provide a seperate circuit for each device. Otherwise, put the processor on one digital and the CDP and DVDP on another digital. What are the chances that you will use both players simultaneously?
Four dedicated circuits. When you asked about running 10/3 w/grd for two circuits sharing the same neutral, the two circuits would be separate circuits not dedicated circuits. A dedicated circuit is a separate hot, separate neutral, and a separate ground. When you run two circuits and share the neutral this is called a three wire branch circuit. One hot,on one recept, is connected to a breaker that is on one line of your service panel and the other,recept, hot will connect to a breaker on the other line in your service panel. The recepts shared neutral to the neutral/grd bar. When you plug a load into each of the two recepts the neutral will carry back the unbalanced load,current,amps, of the two loads. Example, if the load of one recept is 10 amps and the the load of the other recept is 5 amps the neutral will carry back 5 amps to the source. Im going to keep this as simple as I can. If both loads were equal say exactly 5 amps each the neutral will carry back 0 amps, no current. Because of the cofiguration of the transformer feedind your house, without getting technical, what happens is the two loads are in series with each other. A simple series circuit. Not the best for audio equipment. Even in the first example I gave, current travels in series between the two loads. Thats why you should install dedicated circuits. I also believe that all dedicated audio circuits should be connected to the same phase,line, in the electrical panel. Put all the branch circuit breakers on the same line.
You asked about using 10-2 w/grd for each ded cir, that is the most common used. Black insulated wire to the brass colored screw on the recept, white to the silver colored screw and the bare wire to the green grd screw on the recept. Back at the panel terminate the black on a 15 or 20 amp sp breaker. Neutral, white wire, and bare grd wire terminate on the neutral/grd bar. Equipment ground wires must terminate here. With this system you will need four seperate rough-in recept boxes, if you use metal boxes. If you use plastic, or fiber rough-in boxes you can put more than one recept in a common box. You will need to put electrical tape around the bare ground wires so they won`t touch each other.
If you need to use metal rough-in boxes and want to put more than one recept in the same box, I would use 10/3-w/grd romex. Black hot, white neutral, red, tape with green colored marking tape and connect to the green terminal on the isolated grounding type recept. Yes if you have multiple recepts in a common metal box you will need to use isolated ground receptacles. At least one of the bare grd wires of the romex will need to bond, connect, to the metal box. The other end connect to the neutral/grd bar. Also put greem marking tape around the red colored wire and connect it to the neutral/grd bar in the service panel. One other thing about using 10/3 the conductors are installed in a spiral twist inside the outer sheath jacket.
Thank you all so very much for the explanations. I've learned alot from this thread.(Jea48...great explanation). I takes alot of effort to communicate these concepts to the uninitiated. Just a couple of last questions. I met with a very competent electrician this morning and we discussed all the options. Here's what we decided.
1) We'll go the subpanel route and run 3 #4 wires from the
main panel to sub panel (6-8 ft from audio rig once in
2) Breakers will be 20 amp 'square D' type.
Now here's the dilemma and I now understand the differences between dedicated circuit and dedicated line and using 10/2 vs. 10/3.
We were going to go 10/3 in an isolated ground situation and wire each duplex separately. I don't think we'll do that anymore for the above reasons. I think we'll wire each receptacle as a dedicated line and if I don't use the other outlet so be it. I will then have 4 dedicated duplexes in two separate receptacle boxes. 1 for amps (4 outlets on 2 dedicated lines) and the other box also have 2 duplexes (4 outlets) on 2 other dedicated circuits. I just have 3 other questions....
1) Does 10/3 come in solid core copper or is it always
twisted? I understand that solid is the way to go.
Jea48, do you mean the conductors in 10/3 use twisted
or braided wire or that the black,red,white, and ground
are twisted upon themselves (like Kimber 4TC speaker
cable). Not sure why you mentioned this. WHat are the
disadvantages of this configuration?
2) If I decide to run 10/2 from the subpanel I cannot do
an isolated ground scenario. How do I ground 10/2
circuits? Tell me I don't need a separate grounding
rod. If I am using 2 receptacle boxes (with 2 duplex
outlets in each) do I have to always use isolated
ground circuits, thereby calling for 10/3? If I chose
10/2 can I use the main panel grounding wire?
3) When hooking up to the subpanel am I correct in the
thinking that amps go on one side(2,4,6,8 etc.)or the RT
side and the other components on the LT.(1,3,5,7,etc).
Source,analog 3 4 Amps here?
and digital here? 5 6 Will have 2 dedic.
Will have 2 dedic.7 8 lines on this side.
lines on 2 outlets (2 duplexes)
Help, we're almost there....honest! I appreciate it.
Please ignore that last part.It did not come across properly. Thanks.
10/3 romex is solid conductor wire. The way 10/3 is put together when manufactured the three solid insulated and the bare ground wires are in a spiral configuration.
The sub panel is the way to go. If the recepts are only going to be 6' or 8' from the sub panel you would only need the #10 awg wire for the power amps and you could use #12 awg for the other components.
The feed from your main panel to the sub panel. 3#4awg conductors in a 1" emt conduit? Is your sub panel going to be a 120/230 volt or a straight 120 volt panel? I assume it is going to be 120/230v. I take it the electrician is going to use the emt conduit for the equipment grounding conductor. I would spend the extra money and install an additional fourth wire, for the the equipment grounding conductor. By NEC it is sized according to the overcurrent device, breaker in your case, given by a chart in the code book. If the electrician is going to install a 2pole 70 amp breaker to feed the sub panel then the min size equipment ground conductor would be a #8 cu awg wire. For just a few pennies more increase the size to a #6 awg wire. In a sub panel a separate ground bar is required. The neutral bar in the sub panel is for the neutrals only. All the equipment grd wires will terminate on the grd bar. Only at your main service panel do the neutrals and equipment grounds share the same bar. The reason is because this is where the incoming neutral conductor is bonded,connected, to ground, as per NEC. Here you have a choice use a standard grd bar, which is fastened directly to the panel enclosure. The #6 awg grd wire will connect to this bar. The other end of the #6 awg wire will terminate on the neutral/grd bar of the main service panel. Install 20 amp Hosp grade duplex recepts or better with the equipment grds terminating on the sub panel grd bar. Second choice is to install an isolated grd bar. This bar has insulated feet that isolate it from the sub panel enclosure. The #6 awg wire will terminate in the same manner as above. The duplex outlets that would be used now would be Hosp grade or better isolated grd recepts. Each recept with it`s own insulated equipment grd wire back to the sub panel isolated grd bar. Do you really need to go this extra mile, you will have to decide that for yourself.
One more thing, with the 120/230V sub panel, you will be installing equipment loads on both phases,lines, of the service. I am in the camp of having all my loads on the same phase. That is the way I have mine. But a lot people do it the way you are looking at too.
The subpanel will be a 120/230v 60amp panel. OK? In an insulated ground scenario, do you need both an insulated ground bar in the subpanel (for red wires) and also another ground bar for the bare copper wires? Does the 6AWG from the sub to the main connect to the main grounding rod or is another rod required? By installing in the same phase or line at the subpanel, wouldn't I be overloading one side too much? In this configuration, I assume putting 5 outlet on the LT side only in the 1,3,5,7, and 9 positions. Thanks for the class Jea48, how much is the tuition? I sure have picked up alot. If you need medical advice or questions, let me know. Cheers.
If the outlets are going into plastic recept boxes, does the chassis have to be plastic too or does it have to be metal or steel? If using metal recept boxes housed in a metal chassis and bolted to the floor why do all the duplexes need to be in separate boxes? I was planning a 2 duplex chassis for the amps and a 3 duplex chassis for the components, all on separate 10/3 lines. (5 dedic. lines total). Thanks.
Jea is absolutely correct about spending the extra $ to run a ground connection feeder. If it were me, I would also size it at 6Ga. But then, I am the one who suggested being sure to check your entire grounding system to make sure it was adequate or oversized. Make sure that the ground conductors going to your ground sink are also appropriately sized.
If it were me, I would go the extra mile and use the isolated approach. Jea has very clearly shown you your options.
Question to Jea:
With putting all of the audio devices on one phase of service, do you have concerns with load balancing, or are you also using a sub-panel and balancing loads in the main panel? I am assuming from your language that you are using a sub-panel yourself. Yes? Have you wired it 120/230V or straight 120V?
If you decide to use isolated grounding type duplex receptacles and metal enclosures to house them in, then the metal enclosure will need an equipment grounding conductor back to the sub panel. If you choose to use an isolated ground bar in the sub panel then yes you will have a second regular ground bar installed in the sub panel. This ground bar will be for the metal recept enclosures. And the electrician will use the bare copper ground wire in the romex for this. The reason you need to ground the enclosures to your electrical system grounding is for any fault that may occur inside the metal enclosure. You don`t want a hot box. The enclosure equipment ground will carry the fault current back to the sub panel ground bar. And if the fault is large enough will cause the affected branch circuit breaker, in the sub panel to trip open.
It sounds like you are going to use some type of floor boxes. If the electrician uses single conductor wires inside a raceway from the sub panel to the two boxes make sure he uses solid conductor wire only. Not stranded.
120/230V or 120V sub panel? If you added up the total load of all your audio equipment I doubt if it would be more the 30 amps, 3600 watts max continuous full load. Thats a lot of power. But not for your main electrical panel. One thing about it with the type of install you are doing, you can do it either way.
1 - 2.. L1
3 - 4.. L2
5 - 6.. L1
7 - 8.. L2
9 -10.. L1
You said you were going to use a Square D panel. Make sure it is the "QO" type not the Home line style. The QO style is the best.
The #6 insulated equipment ground wire, for the sub panel grd bar, will be installed in the 1" emt sub panel feeder conduit along with the 3#4 THHN cu feeder conductors. It will terminate on the main electrical service panel neutral/grd bar. The sub panel is an extension of the main service electrical panel and all equipment grounding conductors tie back to it. Have your electrician check and clean the grounding electrode conductors terminations, clamps, at the grounding electrodes. Not knowing how old your home is and what type of earth grounding electrodes you have? Do you have a Metallic incoming main water line? Do you have an out side driven ground rod? This is what the electrician will check and clean terminations and clamps.
The home is 10 yrs old, a 2 storey, and has an indoor grounding line. Not sure about the metallic water line but the electrician did mention he would be using some part of the water line. I'll have him clean up the whole deal. Cheers. Dave. Would you ground the subpanel at the main ground/neutral bar or would you install your own grounding bar for the sub panel? Thanks.
Ten years old. If the electrician talked about the water line, than more than likely it is copper, not plastic. That will be one of the grounding electrodes for your main electrical service. I would also bet you have a second grounding electrode, at least one ground rod driven outside your house. Usually close to the panel location.
The sub panel enclosure is grounded by the 1" emt conduit that will run from your main electrical service panel. The emt conduit is an approved means for an equipment grounding conductor. The neutral/grd bar in your main service panel has a bonding screw that bonds,connects, your main service panel enclosure to the neutral/grd bar. This neutral/grd bar is the main star grounding point for your house electrical service. This point is very important. Any fault current that travels back thru any equipment grounding conductor travels thru this bar, then thru the neutral,the grounded conductor, on out to the power company`s transformer outside. Yes your power company even gets paid for your faults. It all goes thru that electric meter.
Jeffcott, I did not install a sub panel. I ran three dedicated circuits from my main electrical panel, the distance was fairly close. Less than 25'. I terminated them on the same phase, line. I installed the branch circuit breakers as close as I could to the 200 amp main breaker. The panel is a "Square D" QO 42 circuit.