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Installation of new AC lines......best way to ground to avoid loops and noise

I plan on installing dedicated (new breaker box near stereo) lines. I already have the AC plugs and am most concerned about configuring the best grounding system. I use single ended interconnects. Any advice would be very appreciated.
audition__audio
jea48
4,268 posts
 
@minorl

First you have a mighty fine 2ch audio system there.

As for your statement stating that dedicated circuits installed to feed an audio system installed in a home must be fed from both 120V Lines, Legs, is not accurate, imo. Would you please cite in the NEC where it says it.

In probably the majority of audio systems in the US and Canada the total combined load of the audio system equipment at best would add up to 8 to 12 amps continuous load at best. One 120V 15 amp branch circuit would be more than enough. Not to mention it would meet or exceed the bare minimum NEC standards. (#14awg copper wire fed from a 15 amp branch circuit breaker.)
If the home owner wanted the electrician to install two 120V 20 amp dedicated circuits fed from the same Line, Leg, I see nothing in the NEC that says it would violate the the NEC.

In your case with your audio equipment I can see and would agree the ARC mono amps should be be fed from both AC Lines, Legs. Yes, to balance the two loads across both Lines of the electrical service panel.
Jim


minorl
1,014 posts
 

First, let me be clear that my intention is to not, I repeat not, get into arguments about the technical aspects (or non-technical) aspects of having your system wired on both voltage legs.

I am an Electrical and Electronics Engineer, well versed in amplifier/filter design and test.  I am also a power Engineer and a state registered power Engineer.

I don't have the in front of me but it is safe to say that in designing home electrical circuits, the Electrician tries hard to balance the house loads on each phase so as to not overload one phase.  So, air conditioners, refrigerators and equipment with large current load are balanced between the phases.

For high end audio equipment, the low level equipment isn't an issue.  However, for ridiculously large class A amplifiers or some such, that is another issue altogether.  If the Electrician has half a brain, he/she is going to inquire as to average load usage and try to balance that load.

This is a non-issue.  What is the issue is to try to not have audio equipment on the same circuits/legs as noisy equipment, such as particular types of lighting.

Ground loops are created by potential (voltage) differences between equipment on a closed loop, which will cause current to flow in that closed loop.

AC from the panel is converted to DC in most audio equipment, so which leg it comes from is really a non-issue.  As long as the ground and neutral run back to the panel and are not shared.  When you share neutrals or the grounding scheme of your system or worse, of a particular piece of equipment is not well designed, that is when you have serious problems.

This is why I tell people when running dedicated lines to make sure each dedicated line consist of a hot, neutral and ground that is run directly back to the service panel with its own circuit breaker and are not shared.

So, say one has two amps and a lot of low level electronics, then ideally, you would want a minimum of three dedicated lines to the panel.  One for each amp and another for the low level equipment, such as pre-amp, tuner, cd player, DAC, turn table, etc.  That I recommend all low level equipment is plugged into a power conditions (tying the grounds together) and that has its own dedicated line.

My ground flow is seriously low. When I installed the dedicated lines, the ground flow dropped to dead silent.  Playing with various power conditioners for the low level equipment was fun as the sound improved with better conditioners. 

Again, most ground loops are caused by voltage imbalances between equipment and seriously poorly designed grounding schemes within equipment.  most newer equipment has a type of star grounding schemes within the equipment. 

If it isn't a loading issue on your panel, then yes, why not?  go ahead and put all equipment on the same leg.  But, it isn't the end of the world.  That is not a ground loop problem.  Also, it is quite easy to move that circuit or circuits to the other voltage leg within the panel if need be.  But, I doubt it is a real concern.

enjoy

minorl
1,014 posts
 

Sigh;  Spell check. 

1.  I don't have the NEC in front of me.

2.  My Ground floor noise level is seriously low. 

enjoy

jea48
4,268 posts
 

minorl said:
Ground loops are created by potential (voltage) differences between equipment on a closed loop, which will cause current to flow in that closed loop.
We are in agreement there.

IF there is a difference of potential between the equipment grounding conductors of more than one circuit feeding audio and or video equipment, that is connected together by wire interconnects, there will be current flow through the chassis, signal ground, of the interconnect connected equipment .

No different than when a difference of potential exists between the shield on an improperly grounded CATV providers coax cable and the equipment grounding conductor of the branch circuit outlet the audio/video equipment is plugged into.

This guy is a well respected EE.
https://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

Jim

Edit:
@ minorl , you can edit your post by clicking onto the sprocket looking symbol below your user name and posted message.

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atmasphere's avatar
atmasphere
11,575 posts
 
Follow the electrical code of your local municipal area.
^^ This.
@jsautter

You gotta get with the program and go balanced!


But-

If you are concerned about ground loops, the thing to do is make sure that the equipment you use has competent grounding systems internally. Using your DVM measure from the ground of an RCA input to chassis; if you read less than 1 ohm ground loops are probable if the ground connection of the power cord is connected to the ground connection of the AC receptacle. So measure for continuity between chassis and the ground pin of the power cord.

If its not hooked up, seriously consider sending the gear back to the manufacturer for repair. This is the 21st century- people may have gotten away with that 40 years ago but its not acceptable now and oddly a bit too common in high end audio...


Also check between the ground of the output RCA; that should not be at chassis ground either.


Competent grounding of audio equipment isn’t that hard, despite the crazy amount of nuance that exists in this topic. IOW if your house AC wiring is done to code you **should** not have any problems; if you do its not the fault of the AC wiring.


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