Dedicated Circuit

jea48,
so I just looked at the breaker panel again. The dedicated circuit is right below my mini-split air conditioning breakers which are dual 30amp. Haven’t used the air yet this year (chilly New England) so not sure If it will generate any noise.
If it does, bummer, have to get electrician back here. Tried to do my homework but should have talked to you first :-(
thanks for your expertise!

So when my electrician installed the 20amp circuit breaker it is in fact right below two other 20amp breakers for the air conditioning units 20amp breakers,(two of them).

120V window air conditioners? If yes one is fed from the same Line as your dedicated circuit and the other A/C unit from the other Line in the electrical panel.

I wouldn’t have installed the breaker for the dedicated circuit directly below the two A/C breakers.

With that said.....

Is the dedicated circuit for your audio system picking up noise from the two A/C branch circuit breakers? Maybe, maybe not. Depends on the quality of the electrical components used in A/C units. Can you hear any difference from your audio system when the compressor in the two units cycle on and off?

I guess you could try listening some late evening, when it has cooled down outside, to your audio system with the A/C units turned off. Then listen again with them turned on. Have someone else turn them on so you can listen to your audio system when they are powered up.

@ jea48,
Thanks very much, I really appreciate the detailed response and learned a great deal. So when my electrician installed the 20amp circuit breaker it is in fact right below two other 20amp breakers for the air conditioning units 20amp breakers,(two of them).
So should this be moved to the other leg or down further with separation between them? I think when these guys work they like to keep things all together nice and neat.

@ audiosaurusrex


I think you misunderstood what the electrician said.

In the typical US residential neighborhood the houses are fed from a single phase step down isolation type transformer. The secondary winding is center tapped. From the two outer most leads, legs, of the winding there is a voltage potential of 240Vac nominal. These two leads, legs, are called the Hot Ungrounded conductors.

From either of the two Hot Ungrounded leads, legs, to the center tap lead, leg, there is a voltage potential of 120Vac nominal. The center lead, leg, is intentionally grounded, connected, to earth at the electrical service equipment panel of the house making it the Grounded Conductor, the Neutral Conductor.

The winding is called a Split Phase secondary winding.

So yes there is only one phase but there are two 120Vac Lines.
Line 1 (L1) and Line 2 (L2). The two Hot 120Vac Lines, legs, are 180 degrees out of phase with one another.


Can one Line, leg, have loads that are connected to it putting AC noise back on it that are noisier than the other Line? Yes it can. Can the noisy Line still have an affect on the Other Line? Yes but to a lesser degree. Depends.

Best thing to do is not install the branch circuit breaker for a dedicated line for audio or video equipment in close proximity, (therein directly across from or directly above or directly below), to a know circuit that has a noisy load/s connected to it. The further away the better. (Note: Directly across from is the same Line as the dedicated circuit breaker. Directly above or directly below the dedicated circuit breaker is the opposite Line, leg.

Here is a good video on how a transformer with a split secondary winding works.
https://www.youtube.com/watch?v=eVamt9IdQd8

Hi jea48
electrician said that with 100amp service everything on the electrical panel is on the same “phase”. While I have a dedicated circuit it still is subject to influences of the rest of the house.
I don’t know if this is accurate or true. Need to do some research on this.

audiosaurusrex OP

38 posts
06-15-2019 12:17pm

So from what I’m told by the electrician because I have 100amp service there is no way to separate the “phase”.

" there is no way to separate the “phase”
What does that mean?

This is a topic where you will get different and conflicting opinions. I run three dedicated 20A circuits. After I installed them, some friends said I should have run four not three. That's how this hobby sometimes goes. Someone may say you missed the holy grail by not doing "X". IMO I think you simply need to try plugging your gear into and your circuit and conditioner in different combinations and go with the result that sounds best to you. FWIW I run 430W mono amps in 2 of the dedicated circuits and run most of my other equipment into a power conditioner that is plugged into the 3rd dedicated circuit. I've tried other combinations. I found having everything plugged into a dedicated circuit helped lower the noise floor overall and it provided me an improvement in my overall SQ--in my system. YMMV

So from what I’m told by the electrician because I have 100amp service there is no way to separate the “phase”. So presently I have a dedicated 20amp circuit for my Krell Digital Vanguard. Because it’s a duplex plug I could just plug my Furman PC into that other plug for my sources. Just wondered if there was any benefit to either separated or all on that 20amp circuit?

+1, on the same phase(w/o shared appliances or dimmers).

Hi,
agree with @lowrider57 
unless you have hungry power amp one line is fine. Secret is to have your components on same phase.

Honestly, you have to try it both ways and decied for yourself which sounds better.

All on the one cct is best unless you've monster power amps.

Very often two dedicated circuits are used; a high powered amp in one line and sources in the 2nd line. Or line 1 is used for analogue components and line 2 for digital. 
To clarify, your second circuit is a shared AC line? Do you know how many other circuits and what devices are on this shared line?
 It's important because you don't want your audio sharing a line with appliances or dimmer lights that add noise. 

If the current draw of your amp isn't too high, then you can plug the entire system into the dedicated line. You have 20 amps to work with. Source components draw very little current.