@tump350 Said:

One circuit for the digital front end, the other circuit for the preamp and monoblocs.

Would you believe all the digital hash going back out on the power AC Lines from the digital equipment is dumped onto the power transformers primary windings of the preamp and monoblocks? Only the unbalanced load(s) current of Line 1, (L1), to shared neutral, and Line 2, (L2), to shared neutral load(s) current return on the 3 wire multiwire branch circuit neutral conductor to the neutral bar in the electrical panel. All of the digital 120V Line to neutral loads (jointed connection in the outlet box) is in series with the Analog 120V Line to neutral loads. The balanced loads are in series with one another and fed by 240V...

Jea48

What the heck are you talking about?

emergingsoul OP

481 posts

12-20-2022 at 08:52am

Jea48

What the heck are you talking about?

@emergingsoul ,

Probably the biggest reason for installing more than one Dedicated Branch Circuit is to decouple the power supplies of audio equipment from one another. Example digital source(s) equipment from analog equipment.

A true dedicated branch circuit has a dedicated Hot conductor, neutral conductor, and equipment grounding conductor. A true dedicated branch circuit does not share a raceway, (conduit), or cable with other branch circuits.

Your thread title:

Wiring 2 outlets to 2 dedicated 20 amp circuits with a single 10/3 electrical wire.

What you are suggesting using is called a multiwire branch circuit. It has two 120V separate circuits, (Not Two Dedicated Circuits), that share a common neutral conductor. Bad for audio equipment, imo... It’s actually worse than installing two 120V dedicated circuits and terminating on breakers from Both Line 1, leg, and Line 2, leg instead of installing both on the same Line, leg.

A multiwire branch circuit actually couples the power supply’s of audio equipment of one circuit to equipment on the other circuit.

Here is another video for you to watch. Imagine the output of the split phase transformer being an electrical panel. Imagine the voltage is 120/240V. (Two Hot conductors and one shared neutral conductor). The wires leaving the transformer secondary is a multiwire branch circuit. The single light bulb load represents digital source loads. The other bulb with the parallel resistor load represents a preamp and power amp.

Only the unbalanced load current of the two hot conductors return on the shared neutral conductor to the source. The balanced load is in series with one another and is fed by 240V.

FWIW, multiwire branch circuits are commonly used in commercial and industrial facilities. Why? It saves material and labor costs. It’s even used, somewhat, in residential dwellings. It has its place of use. I personally would not use a multiwire branch circuit to feed my audio equipment though. YMMV.

Here is another video I found doing a quick Goggle search. The guy does a good job of explaining how a multiwire branch circuit works. He does have a few problems in his explanations and terminology used at times though. Like his use of saying 220V at times instead of 240V. Overall though he gets his message across.

Note..., only the unbalanced load current returns on the common neutral conductor to the source. The balanced load current is in series and is fed by 240V. Voltage drop across each load will still measure 120V nominal. (As long as the common neutral conductor is not broken)...

Yes I know both new circuits or an alternating legs, and that could be a real weakness. But if all the legs where I live are generally quiet then I don’t see the problem on this point.

The other issue, there is a common neutral wire representing a return connection to the panel, but it’s not the incoming voltage wire. Are you saying noise could bleed back to the audio equipment from the neutral? I’m not sure this is really that meaningful - is it? And is this the overall point?

Keep in mind this is a 70 foot run for a romex wire.

I’m trying to keep this conversation understandable because I think people get lost when it’s not dumbed down for non-engineering finance side people

@jea48 Wrote:

 I personally would not use a multiwire branch circuit to feed my audio equipment though. YMMV.

I agree 100%. 😎