Dedicated circuit for each outlet pair?

[tima]

I don't think I thought about that explicitly, but wouldn't that create another possible source of different potentials to ground?

I don't know why that would be. Suggest checking with your electrician. Or ask
@DonH50 in this thread: https://www.whatsbestforum.com/threads/ground-loops-101.19891/

 

[bazelio]

If one requires greater than 15A (or 20A) per outlet, then individual circuits to adjacent outlets is the solution. But if there is no such current demand by the audio equipment then there's really no point in separate circuits other than perhaps future scalability. These "separate circuits" are shorted in the sub panel or main breaker box anyhow.

 

[DaveC951]

Yes it does. Thanks Dave. It leaves me in a bit of a dilemma. My existing 200A service box has every single slot (or two slots for high current circuits) taken up with a breaker. So part of my wanting to add a separate box for my listening room is practical. I may free up one or two 15A breakers in the existing box going to the room, but that will be more than offset by the likely 6 to 8 breakers I would wind up adding to the listening room box.

So you do indeed have a more complex situation, but there is a solution. In your case you're forced into having a sub-panel (a second box of circuit breakers). In this case, you will feed the sub-panel with 120v (single line from your main breaker box on a single breaker, hence on one phase) using something like a 40 or 50 amp breaker. Then all breakers in your sub-panel are on the same phase by default. Your sub-panel can then have the required number of breakers for the number of duplex outlets you wish to have; example, 5 20-amp breakers feeding 5 separate outlets. The amperage of the individual breakers will be greater than the single breaker feeding the su-panel, but this is normal; just like is true in your main breaker box.
Important: While some would question why have more outlets / feeds than one or two, the answer is that it provides built-in isolation between the lines. For example, much of the higher frequency hash that digital equipment feeds back onto the AC line will have "fallen off" by the time it gets all the way back to the sub-panel and back to another outlet. This is easily proven with a scope or spectrum analyzer. It is why many of us have separate lines for each class of equipment: turntable motor, analog (phone preamp / preamp), digital gear, amps (1 feed per amp), video gear (if appropriate).
Good luck with your project!!

 

[Alrainbow]

I spoke to an electrician a little while ago and this came up. He remarked that a “proper” (whatever that means) electrical distribution from the breaker box would have the phase load balanced. I should have asked him why, or what bad things could happen if it wasn’t, but I didn’t.

No it’s not what you want this hurts and adds noise but hey he is an expert lol.

 

[Alrainbow]

So you do indeed have a more complex situation, but there is a solution. In your case you're forced into having a sub-panel (a second box of circuit breakers). In this case, you will feed the sub-panel with 120v (single line from your main breaker box on a single breaker, hence on one phase) using something like a 40 or 50 amp breaker. Then all breakers in your sub-panel are on the same phase by default. Your sub-panel can then have the required number of breakers for the number of duplex outlets you wish to have; example, 5 20-amp breakers feeding 5 separate outlets. The amperage of the individual breakers will be greater than the single breaker feeding the su-panel, but this is normal; just like is true in your main breaker box.
Important: While some would question why have more outlets / feeds than one or two, the answer is that it provides built-in isolation between the lines. For example, much of the higher frequency hash that digital equipment feeds back onto the AC line will have "fallen off" by the time it gets all the way back to the sub-panel and back to another outlet. This is easily proven with a scope or spectrum analyzer. It is why many of us have separate lines for each class of equipment: turntable motor, analog (phone preamp / preamp), digital gear, amps (1 feed per amp), video gear (if appropriate).
Good luck with your project!!

Wow all of your suggestions are good
Glad you posted
What are you grounding thoughts ?

 

[steve williams]

So I’ve been working through some things with my designated sound room in my new home. My first decision is that - while I could knock down a wall and remove a bathroom, to expand the space to 14x21x9, I’m going to see first if I can get the existing 14x16x9 size to work. I know it’s not as ideal dimensionally, but I was really not wanting to lose the very bathroom that would be used by other audio enthusiasts who’d come to listen to my system.

So electrically, across the front wall there are two perfectly placed outlets to drive my Pass monoblocks. There’s another outlet in the center of that wall if it turns out something needs to go there, and other outlets along the remaining walls for possible equipment location. So I intend to have a dedicated sub-panel installed for this room. But the question I have is - is it the right approach to run direct lines to each outlet location, and have those lines each run to its own breaker? I know in a lot of normal house wiring, there is a lot of series wiring done for, say, a room, so that one CB can typically handle a normal sized space. What’s the best approach for a dedicated sound room?

That's what I did. With each run the same length.

I did exactly the same when I built my room. I have 12 dedicated AC lines in the room . I installed a separate sub panel for my sound room that then links with the house breaker panel

 

[microstrip]

That's what I did. With each run the same length.

Can I ask what is the point of having the same length?

 

[microstrip]

(...) But the question I have is - is it the right approach to run direct lines to each outlet location, and have those lines each run to its own breaker? I know in a lot of normal house wiring, there is a lot of series wiring done for, say, a room, so that one CB can typically handle a normal sized space. What’s the best approach for a dedicated sound room?

I would say it depends a lot on the system. Separate direct lines minimize current through each line and increase effective length between pieces of equipment - it could be a good thing to avoid mutual RF noise coupling between units, all equipment radiates some self generated noise through power cables.

However the direct line approach increases significantly the loops created by power lines, including the mandatory ground wire - in some cases it can be problem, as it collects much more induced noise. Each case is a case - e.g. balanced and single end equipment have different susceptibility.

BTW I am assuming you are not wanting to risk your safety violating the code!

 

[Alrainbow]

I would say it depends a lot on the system. Separate direct lines minimize current through each line and increase effective length between pieces of equipment - it could be a good thing to avoid mutual RF noise coupling between units, all equipment radiates some self generated noise through power cables.

However the direct line approach increases significantly the loops created by power lines, including the mandatory ground wire - in some cases it can be problem, as it collects much more induced noise. Each case is a case - e.g. balanced and single end equipment have different susceptibility.

BTW I am assuming you are not wanting to risk your safety violating the code!

if you increase the size of the ground or use one very large ground in a star point configuration using an isolated outlet it makes good sense. if not I’m with you and why the same length I’m scratching my head bit it just sounds good

 

[bazelio]

Yeah, I was also going to suggest something like pigtailing the outlet grounds into a star arrangement in a situation like this to remove all doubt. Same length is probably attempting to minimize inductance variation from circuit to circuit, but other than substantial length variances, it wouldn't matter. I'd prefer to remove all doubt by handling the ground scheme directly. I've done it this way in my own system. I have 6 outlets, 2 circuits, and zero hum.

 

[tony22]

So you do indeed have a more complex situation, but there is a solution. In your case you're forced into having a sub-panel (a second box of circuit breakers). In this case, you will feed the sub-panel with 120v (single line from your main breaker box on a single breaker, hence on one phase) using something like a 40 or 50 amp breaker.

Dave, where does this large breaker get located? I’m trying to picture in my head tapping off one phase from the input to the main box. Does the 50 amp breaker get placed somehow between that and the secondary box?

Yeah, I was also going to suggest something like pigtailing the outlet grounds into a star arrangement in a situation like this to remove all doubt.

bazelio, if each individual line plus ground is brought back to the secondary panel, wouldn’t it be possible at that point to create effectively a “star” ground?

 

[bazelio]

There's nothing to do in the sub panel as there is already a ground bus.

 

[DaveC951]

Dave, where does this large breaker get located? I’m trying to picture in my head tapping off one phase from the input to the main box. Does the 50 amp breaker get placed somehow between that and the secondary box?



bazelio, if each individual line plus ground is brought back to the secondary panel, wouldn’t it be possible at that point to create effectively a “star” ground?

All sub-panels are, as the name implies, a "sub" off a "main". So the configuration is a breaker in the main panel that feeds the sub-panel. Being more specific, the 40 or 50 amp breaker goes in your main panel. Then HEAVY cable from the main panel to the sub-panel (separate discussion on size of cable). This 40/50 amp feed acts as the main feed for the sub-panel. Each breaker in the sub-panel draws from this single line to the main panel, which in our case is a single feed and thus all on the desired same phase.
Hope this makes sense. Feel free to give me a shout if you want a personal conversation: david@djcurtin.net or 917-209-7372.

 

[tony22]

There's nothing to do in the sub panel as there is already a ground bus.

Right, but if all individual grounds are directly tied back to that point, isn’t it a star?

 

[tony22]

All sub-panels are, as the name implies, a "sub" off a "main". So the configuration is a breaker in the main panel that feeds the sub-panel. Being more specific, the 40 or 50 amp breaker goes in your main panel.

Ah, I thought the heavy jumpers were on the input side to the main panel, paralleling the service input to the secondary panel.

This means I’ll have to pull at least 2, possibly 3 in use circuits on the main panel in order to put a larger feed breaker in place.

 

[bazelio]

Right, but if all individual grounds are directly tied back to that point, isn’t it a star?

Yes but the physical topology and loop inductance is different.

 

[tony22]

Yes but the physical topology and loop inductance is different.

Yes, I understand. So, what if I star ground the individual grounds as quickly as possible in the attic space above the listening room (in Florida, electric runs through the attic - concrete pad homes), then from that point run a single 10 AWG back to the panel?

 

[microstrip]

if you increase the size of the ground or use one very large ground in a star point configuration using an isolated outlet it makes good sense. if not I’m with you and why the same length I’m scratching my head bit it just sounds good

The isolated outlet will not solve the intrinsic grounding troubles of most systems. Due to code requirements chassis and ground plane must be connected to the safety earth pin of the mains connector - we can't avoid loops, we can only minimize them.

The tricky question - if you have an high-system in a plane, will it sound better when the plane is flying or when it is grounded and its body is connected through a custom wire to a set of audiophile ground rods? Please ignore the motor noise and the air pressure difference.

 

[DaveC951]

Ah, I thought the heavy jumpers were on the input side to the main panel, paralleling the service input to the secondary panel.

This means I’ll have to pull at least 2, possibly 3 in use circuits on the main panel in order to put a larger feed breaker in place.

Not exactly, the single phase 40 or 50 amp breaker you buy is a single width breaker, just like all the other narrow 120v breakers in your panel. SO you only need to remove one.

 

[BlueFox]

Is it possible to have a sub-panel that is also connected to the main AC power coming in?