Main vs. sub panel for dedicated lines
I am building a second home on my property. Will have a dedicated audio room. I will be routing 2 or 3 dedicated lines for my audio system. The high current devices for the home will be run off the main panel. I will install a sub panel supplied by the main to accommodate power for 2 bedrooms and a 1/2 bathroom.
Question, should I run my dedicated lines off the main or the sub panel? I could move some of the high current devices to the sub panel if needed.
Thanks in advance for advice.
Question, should I run my dedicated lines off the main or the sub panel? I could move some of the high current devices to the sub panel if needed.
Thanks in advance for advice.
38 responses Add your response
I am unclear as to what you are doing with this second home. If it really is a second home it would have its own service and panel. If you are running it off of your main panel then yes it would be a sub panel situation. If the listening room is in this second building then you would run the ONE dedicated listening room line to this sub panel. Main thing is there be one dedicated line, and everything in the system uses this one line. All the lights and other outlets for accessories, you can run as many lines as you want for those. The system however, it all goes on one line. The relevant comment from Michael Fremer starts at 15:50 https://youtu.be/H07NpWk_Xf8?t=950 |
Different philosophies regarding dedicated lines. Use one line if all your component’s amperage is less than the 20A breaker. The takeaway is no ground loop. Use more than one line if separating digital and analogue, running high current monoblocks, or running subs. Lighting should be moved to other panel. Certain lights and dimmers will cause hum to audio system. These circuits should be wired into the same leg (phase) in the service panel. In your current situation, dedicated lines should be run from the panel without the high-current devices. Although both panels will share hot, neutral and ground, the breakers are further away from the appliances that generate noise on the mains. Two ground rods need to be drilled into mother earth according to your local code. The electrician will know this. |
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I feel that I did not provide enough info in trying to be succinct in my question. In my current house I have 3 dedicated lines serving my system. These lines run from the only panel. I used 2 lines for analog and 1 for digital. The new home is a remodel of an previously built building which is serviced by it's own meter and electrical panel providing 200amps service. I have added an addition to this building which will house 2 bedroom and 2 bathrooms, one a full bath and utility room and and one a 1/2 bath. One bedroom will house the audio system. I was going to use the sub panel for this addition to provide more lines. The original main panel could be used for high current items in the utility room. I have a experienced electrician who I consult with and helps me. Most interior wiring for both homes I did myself. I will consult with him on all aspects of my plan and adjust accordingly. He is not an audio enthusiast. My thinking was I would use 2 10ga. dedicated lines for my system, 1 for analog and 1 for digital. Both on the same leg of the Panel serviced by 20amp breaker for analog and 15amp for digital. My question was to solicit from experienced audio enthusiasts suggestions on which panel I should use to provide the dedicated audio lines. My initial thought were to use the sub panel. I thank all who have provided input and hope to receive additional thoughts. Thanks, Mike |
How far away from the main panel is the listening room and the two bedrooms and bathroom? The only reasons for a subpanel is to limit the voltage drop over long distances, or to group together outlets in a common area so as not to overstuff the main panel (i.e. a garage woodworking shop with numerous 240V circuits for power tool motors). To give you a perspective: a #12 branch line carrying a load of 10 amps can be run up to 75 feet to keep the voltage drop under 2.5%. That is a lot of amps. If you go with #10 wires, then you can go up to 125 feet for a 2.5% voltage drop. Since you have a dedicated service drop for the second structure, I see no reason for a subpanel with only three audio lines, one GFI bathroom circuit and one or two AFI bedroom circuits. Unless it is quite a big house. |
Mike, if you're using 10 gauge wire the breakers should be 20A. There's no reason to use one 15 and one 20A. If you use 10/2 Romex, you would use two 20A receptacles for your audio. As stated before, use a subpanel for audio. Main 200A panel will have high-current draw appliances, lighting, and household devices. Each panel will have an 8' ground rod, check with electrician for code. |
Each panel will have an 8’ ground rod, check with electrician for code.If the sub panel is located in the same building as the main service panel a ground rod is not required for the sub panel. Yes per the NEC a driven ground rod can be connected to the equipment ground bar in the sub panel. (2017 NEC 250.54) I would not recommend it though. If the sub panel is located in another building, such as a detached garage, then a new grounding electrode is required and bonded to the equipment ground bar/ panel enclosure/feeder equipment grounding conductor. (Feeder neutral conductor is never bonded to ground in a sub panel. Neutral conductor/ bar shall be isolated from ground/ panel enclosure.) Minimum required number of driven ground rods for the main service panel technically is one, * IF *, the ground rod to soil resistance is 25 ohms or less. How can the electrician know for sure if it is 25 ohms or less? With testing equipment that is made to test it. If an electrical inspector sees only one ground he will ask to see a print out of the test. It is cheaper by far for the electrician to just drive two ground rods and be done with it. |
mesch, makes absolutely do difference. In order to isolate your system from everything else your would have to have the power company install a separate high voltage transformer on your lawn and run a second main from that to run the system, just a bit absurd from a financial standpoint. For good equipment it does not matter. I have a three phase workshop in my bottom floor. I can run the phase converted, stop and start machinery and you can hear the tiniest click in the system. All of this is running off the same main. The power company did make me get my own transformer but this was to isolate my neighbors from me, not me from myself. |
Just to add to why a sub panel(s) may be needed. For one because a 42 circuit main panel (If main breaker is in the panel 40 spaces/circuits for branch circuits) isn’t enough spaces/circuits for all the circuits need for the home. I have a sub panel for just that reason. It is mounted beside the main panel. (42 circuit used to be the max for an electrical panel. That was changed a few NEC code cycles back. There is not any limit now to the number of spaces/circuits in a panel enclosure.) Sometimes a sub panel is used because of the distances lengths of home run branch circuits. Not for just branch circuit voltage drop. Considered is material and labor, it is cheaper to install a sub panel than run several branch circuit home runs back to one panel. And again one panel was not big enough. Another reason for more than one panel is the size of the electrical service. Two main disconnects are located on the outside of the house by the electric meter, (Often in a common enclosure with the meter socket). Each main breaker will feed a sub panel. They both might be side by side or separated from one another for splitting up branch circuit home runs. . |
Lowrider57, I will use 10 ga and 20 amp breakers for each line. Or I will use 12 ga and 15 amp breaker for the digital one. I will use high grade 20amp receptacles for each line. Jea48 hit on the reason for the sub panel. I need more circuits. And also the fact that I may not need the sub connected to ground rod. I think I have been told that this depends on the distance between panels, if too close there can be problems. The distance between the two panels will be less than 15'. I will ask my electrician regarding need for this and do as he says. gs5556, No circuit will require a length of Romex longer than 50' so voltage drop should not be a concern. Mijostyn, yes I thought that it would likely make no difference, however since I need(want) a sub panel I thought I could isolate high current circuits from those supplying outlets, lights, and the audio system in the addition. Thanks all! |
And also the fact that I may not need the sub connected to ground rod.Like I said I would not recommend it. It will not improve the sound of your audio system. In fact it may degrade the sound. Lightning loves an auxiliary grounding electrode though. Lightning strike travels through the earth, enters the aux ground rod travels up through the ground wire to the equipment ground bar on its way to the main electrical and on its’ merry way back to earth. Suppose it stops and looks around inside the sub panel on its’ way back to earth? The earth does not possess some magical mystical power that sucks nasties from audio equipment. Adding an additional ground rod to the main electrical service Grounding Electrode System may lower the grounding electrode to soil resistance. IEEE recommends 5 ohms or less. FYI the main reason for connecting the electrical service to the earth is for lightning protection. You can have as many ground rods installed for the main electrical service as you like as long as they are all tied, connected together, and connect to one point at the electrical service equipment. No matter how many electrodes there are they are counted as one. The distance between the two panels will be less than 15’.How big/size, ampere handle rating, will the two pole breaker in the main electrical panel be that will feed the sub panel? Feeder wire size? . |
@jea48 @lowrider57 I will consult with my electrician on the amperage supply to the sub panel and the need for sub panel ground rod. Regarding audio quality would I benefit from running my system through a sub panel that only serves low amperage devices, my amplifier likely the highest one, over running it off the main panel to which the sub panel is attached? |
lowrider574,352 posts@lowrider57 Two rods yes. Both should be for the main electrical service panel. (Reason for two as I described in my post above.) If you would, go out side where the two ground rods are located and look if you see only one bare ground wire going into the house and not two ground wires. The correct installation, the two rods shall be a minimum of 6ft apart from one another. The two rods are connected together with a ground wire that is then extended into the house and connects to the service entrance neutral conductor buss bar. The neutral bus bar is bonded/connected to the panel metal enclosure. The two rods are counted as one Grounding Electrode, (NEC). . |
I'm confused about the second (set) ground rod for the 2nd panel issue. I'm familiar with installing two ground rods and connecting to the main panel. Sometimes a second panel (subpanel) is installed on a 2nd floor of a house for circuits in a bedroom, lights, etc... so are people suggesting we run a ground wire outside from there and connect it to a ground rod (or two)? A sub panel connection has different rules than a main panel. |
For a sub panel in an out building, separate building, a ground rod (Grounding Electrode) is required. The ground rod is connected to the equipment ground bar in the sub panel creating a grounding electrode system for the separate building. For a sub panel located in the same building as the main electrical service panel the separate earth connection ground is not required. If not required why would anyone want it? The separate earth connection can/does cause more harm than good. In fact the separate earth connection can/will add noise to the branch circuit equipment grounding conductors connected to the earth connected ground rod. This guy has helped over the years in writing parts of the National Electrical Code, (NEC). Auxiliary Grounding Electrode. (NEC 250.54) https://www.youtube.com/watch?v=gg4wBI7bWgI . |
@jea48 Hi Jim, the service I mentioned is the one where you kindly offered advice. Installation was from the drop to a new meter, then inside to a Square D 100A panel, 60A subpanel. This is a small Philly rowhome where outside the house is pavement. Now don’t freak out, this might be Philadelphia code; both grounding rods are drilled into the basement cement floor near the rear wall. They’re 3’ apart, sunk into mother earth. I can only see one rod which is wired to the main panel. The 2nd rod is obscured behind my washer/dryer. I will look for the wire. Question: why are two ground rods used? I’m guessing the second rod isn’t wired to the subpanel because the main panel is ground, correct? |
What difference does it make? The sub panel is still receiving power from the main panel. Just go to main panel and fit a new 20 amp breaker, or if no room a piggy back breaker. Then use 20 amp 12 gage romex, the yellow jacketed romex. If you like making more work for yourself, then use 10 gage romex...to me, no benefit and way to stiff, over kill....then install a stand alone receptacle contained in a handy box. I’d recommend the audioquest nrg Edison receptacle and cover plate, excellent quality. This is an easy diy project. If the main panel is of 200 amp service, I’m having a hard time seeing the need to add a sub panel. You are in no way going to tax the main panel by running audio equipment. |
lowrider574,353 posts Hi @lowrider57 From one of my above posts: 06-02-2021 8:24am Minimum required number of driven ground rods for the main service panel technically is one, * IF *, the ground rod to soil resistance is 25 ohms or less. I am curious what’s going on with the two ground rods in the basement. Sure would like to know. 3 ft apart? Not 6 ft apart? Are the two rods connected together by a bare #6 solid copper wire? How about the old ground rod that was used for the old service? Did the electrician use it for the new main electrical service as one rod and the new rod(s) in the basement for the other? Curiosity killed the Cat..... Best regards Jim. |
I would also recommend grounding the ground to ground, and then grounding the Earth to ground. You never can be too sure, so I would ground all the grounds to all the pipes as well. Because, like, they go into the ground. Yeah, I know what you're thinking. There he goes being a a-hole again. But no, this actually is code now. The difference between all this BS everyone is so intent on doing, and what actually works, is so obvious if you could hear it that would be the end of that. But you can't. It is way too much work. You never in your life will do it to compare and know. That's why I did it. To know. Then comes the reason I hardly ever bother posting on the subject, https://youtu.be/9FnO3igOkOk?t=39 |
millercarbon9,434 posts MC, finally a post of yours that makes sense. :) Broken down into simple English. To earth ground a sub panel or not to earth ground a sub panel that is the question...... . |
MC, I was looking at your system thread and read this: Stewart Marcantoni taught me it all begins at the wall. The System begins with 4 ga wire at the panel. This 4 ga brings 240v power to a step-down transformer located just beneath the system. Now at 120v, it is only about 5 ft from the Medusa power center. The step-down transformer and Medusa are both grounded to the same ground rod the same 5 feet from the system. Power wire is all cryogenically treated.@ millercarbon , I have some questions if you don’t mind. What size, (breaker handle rating), is the 2 pole breaker, at the main electrical panel, that feeds the primary winding of the isolation power transformer? What size, VA rating, is the isolation power transformer? Does the secondary have overcurrent protection? Are connected circuit(s) wiring protected? Is the secondary, one winding, or two windings? In other words can the secondary be wired for 240/120V out or 120V out only? Is the ground rod used to earth ground the new separately derived power system? Is one of the 120V secondary winding leads intentionally grounded making it the neutral, The Grounded Conductor? Is the neutral conductor bonded to the transformer metal case/metal enclosure/ transformer Iron core? Are circuit EGC(s) (Equipment Grounding Conductor)(s) connected to this star equipment grounding point? Is the ground rod bonded to the main electrical service "System Ground"/"Grounding Electrode System" with a minimum #6awg copper wire? OR, Are you floating the 120V secondary? (No reference to ground from either lead/leg of the 120V secondary of the xfmr? An Ungrounded Power System.... The ground rod is only connected to the 120V EGC(s) connected loads. Ground rod is not connected to the main electrical service Grounding Electrode System. FWIW Fact. Mother Earth does not possess some magical mystical power that sucks nasties from audio equipment. Grounding myths from somebody that knows something about grounding. Henry W Ott Quote: Grounding Myths "Electromagnetic Compatibility Engineering" by Henry Ott 3.1.7 Grounding Myths More myths exist relating to the field of grounding than any other area of electrical engineering. The more common of these are as follows: 1. The earth is a low-impedance path for ground current. False, the impedance of the earth is orders of magnitude greater than the impedance of a copper conductor. 2. The earth is an equipotential. False, this is clearly not true by the result of (1 above). 3. The impedance of a conductor is determined by its resistance. False, what happened to the concept of inductive reactance? 4. To operate with low noise, a circuit or system must be connected to an earth ground. False, because airplanes, satellites, cars and battery powered laptop computers all operate fine without a ground connection. As a mater of fact, an earth ground is more likely to be the cause of noise problem. More electronic system noise problems are resolved by removing (or isolating) a circuit from earth ground than by connecting it to earth ground. 5. To reduce noise, an electronic system should be connected to a separate “quiet ground” by using a separate, isolated ground rod. False, in addition to being untrue, this approach is dangerous and violates the requirements of the NEC (electrical code/rules). 6. An earth ground is unidirectional, with current only flowing into the ground. False, because current must flow in loops, any current that flows into the ground must also flow out of the ground somewhere else. 7. An isolated AC power receptacle is not grounded. False, the term “isolated” refers only to the method by which a receptacle is grounded, not if it is grounded. 8. A system designer can name ground conductors by the type of the current that they should carry (i.e., signal, power, lightning, digital, analog, quiet, noisy, etc.), and the electrons will comply and only flow in the appropriately designated conductors. Obviously false." Henry W. Ott Who is Henry W Ott? http://www.hottconsultants.com/bio.html . |
Run the lines from your properly grounded sub panel and be done with it. Buy hospital grade plugs. I think I ran 10 gauge. So long ago I don’t remember. I did put in a new grounding rod and a more robust grounding strap when I ran the dedicated lines. I believe the wire from the pole to my main in the garage is aluminum? I know the wire from the main to my sub is aluminum. It is current no more no less. Stable Hz is as important as anything when it comes to electronics. Depending on where you live line voltage could be anywhere from 114v - 120v. But I’ve been in many an industrial plant that had 208v lines. |