Dedicated Line Advise


I currently have a 20 amp dedicated line run to my small HiFi rig; amp, preamp, CDP, TT, power conditioning. I wish to add a second line using the same electrician who has worked on my house. It looks like he used 12 gauge Romex last time.

What are the key facts that I should know in case he is not familiar with doing wiring for audio systems?
I'm talking about the installation at the breaker box, e.g., keeping proper phase and preventing a ground-loop between the 2 circuits.
128x128lowrider57

Showing 2 responses by almarg

Lowrider, I’ll just add to the many excellent comments that have been provided the suggestion that it may be worthwhile to re-read this thread from about two years ago. Note particularly the comments by electrician expert extraordinaire Jea48 (Jim). And in regard to ground loops, which you had asked about in your initial post above, note especially his reference to pages 31 through 37 of this paper.

It is explained in those pages that what "drives 99% of all ground loops" (to a greater or lesser degree depending on the designs of the specific components that are involved -- my words) is lack of uniform geometry in the power wiring. Which in turn results in the magnetic fields surrounding the hot and neutral conductors, that would ideally cancel each other perfectly at the mid-point between the conductors due to the currents which produce those fields being in opposite directions, cancelling less than perfectly, and therefore causing voltages to be induced in the safety ground wire. Which in turn will result in ground loop issues to a degree that depends on how safety ground and signal ground are connected to each other within any pair of interconnected components.

As you’ll see in the paper, the Romex you indicated is being used in the existing run is a good choice in that regard, given its essentially uniform geometry.

Note also the list of common sources of high frequency noise, on page 37.

Good luck. Best regards,
-- Al

Having worked on this issue extensively with many different systems, the chance of getting ground loop hum when powering equipment from the two opposing phases in your panel is greatly increased. While I agree that in theory it should not matter, in practice in most cases it does.
According to a reference authored by world renowned authorities on relevant aspects of electrical and electronic design, which was cited in this thread, it even matters in theory. See the first of my two posts in that thread dated 5-16-2013, which provides brief relevant excerpts of their paper, as well as my comments on it. The paper was initially cited and commented on in the thread by electrician extraordinaire Jea48 (Jim).

The thread also contains further discussion of both this issue and the criticality (or lack thereof) of load balancing, by me, Minorl, Peter (pbnaudio), and Jim (Jea48) among others.

It would seem that those on opposing sides of these issues will just have to agree to respectfully disagree. As for me, FWIW, I’m with Peter and Jim on these issues.

Best regards,
-- Al