Another question about dedicated AC lines

Power Components
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Hello - I’ve been lurking here for a bit and have read a number of conversations about dedicated power lines. I’m setting up a small listening room in my 1950’s era house here in the US and would appreciate some input from folks as to the best way to approach this. I’m pretty handy and have run dedicated lines for other purposes, but nothing for audio.

I’m planning on running 10AWG cable from my service panel to the room, which is about 50’ away. This circuit will terminate at a pair of 20A hospital grade outlets (possibly isolated ground, one of the many considerations for this little project).

So I have questions about the type of cable to use and whether it makes a significant difference to run 10/2 Romex or if it would be “better” to run an armor clad cable (to reduce/eliminate and possible EM interference). Some possible options:

• 10/2 Romex pulled into a fiberglass “old work” box. The ground conductor in this scenario would effectivey act as an isolated ground since its not grounding anything else.

• 10/3 MC cable pulled into a metal “old work” box. The ground conductor would be used to ground the box and the 3rd conductor would be used as an isolated ground.

Using 10/2 Romex would certainly be easier and less costly, but if there is some benefit to using the “shielded” MC cable then I have no problem going that route. Although if I go the IG route…I’d really need to run TWO circuits so that each receptacle would have its own isolated ground. I know some folks prefer to keep their analog and digital equipment separated in this way (although they are still on the same leg/phase on the panel).

I’m obviously not an electrician but have absorbed a fair bit of knowledge along the way and am comfortable doin gthis work myself. I’m likely way over-thinking this but want to do it properly the first time! What I’d most like to get input on is whether the MC cable really helps with mitigating any EM interference, and also if isolated ground is desirable.

As an aside, I find it “interesting” that NONE of the audio grade outlets come in a Decora style, but instead the old school design. I’ve gone to some lengths to replace all of the switches, outlets, etc in my house to the Decora style and I just CAN’T install any of these audiophile receptacles (PS Audio, Cardas, Furutech, SR, etc), as much as I really want to. I’ll probably just source some hospital grade (and possibly IG) receptacles and use those. Aesthetics are important! Pic for reference. This is just a standard 15A Lutron outlet I have in my living room but you get the idea:

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:slight_smile:

I will appreciate any constructive comments or feedback on the most sound approach with this. I’d like to get this done before my new system gets delivered! Magnepan 1.7’s and a Rogue Cronus “Dark”…a modest system by most standards but its a big comittment for me.

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Interesting project - one that I would like to do someday. I don’t have any wiring wisdom, but I do have a potential solution to the decora outlet look with a audiophile outlet function. See this link for an idea: https://www.homedepot.com/p/Commercial-Electric-1-Gang-Duplex-Cover-up-Plastic-Wall-Plate-Adapter-White-Textured-Paintable-Finish-PPAW-D/300716785

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thoughts?

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It’s worth trying! Kind of a kludge but low cost enough to give it a go.

Thanks for the post!

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Welcome to the forum! I undertook a similar project to what you describe. I bought most of what I needed from VH Audio. Chris VenHaus runs the site and is very responsive to any questions you might have.

For the wire, I used cryo-treated 10-2 (10 AWG) Romex.

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I splurged on the Furutech NCF GTX Rhodium AC receptacles and cover plates. I know you mentioned you favor the Decora style but these look great (to me), have a strong grip and apparently perform some nano-crystal magic to make everything sound better. Once you plug in a couple of Stealth cables, nobody will know whether there’s a Decora receptacle.:blush:

Lastly, I’d suggest you consider something to protect the equipment on your dedicated lines from lightening, surges, etc. I’m using two devices from Environmental Potentials - an EP-2050 AC Surge Protector and an EP-2750 Ground Filter. Both are installed adjacent to the breaker panel. Technical details and spec sheets can be found at the link provided.

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Enjoy your project!

2 Likes
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Thanks! I will check out the EP products. We just did a 200A “heavy up” and part of that upgrade was a whole-house surge protection system. The ground filter looks interesting and I will check that out.

The cryo-treated Romex also pretty interesting. Pretty significant upcharge over standard 10/2 Romex, and I understand why after reading about their process. At this point a few hundred dollars is negligible.

:wink:

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Welcome to the forum.

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Thanks!

:slight_smile:

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Bumping this back to the top. Still looking for some input regarding “metal clad” cable vs NM “Romex”. 10/2 MC is a little harder to source (only comes in longer spools) but if there is a benefit to using it then I will consider it more strongly.

:slight_smile:

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IME, neither. Use solid copper 10 AWG THHN, the three conductors braided together (yes, that’s a bit of work) - ideally grain oriented. Carlon conduit. If your circuit(s) is/are cleanly single point grounded to your incoming house ground, you should be fine. My circuits are a bit more over the top, but that’s essentially how I did it. Audiophile friends to a one, some with an order of magnitude more money in their systems than me, comment on how dead black my system is. No one else has (not) heard anything like it. Throwing more stuff at it - armored conduit, independent grounded outlets, etc - IME and IMO is no substitute for getting the fundamentals done right. I’ve done different types of dedicated circuits more than once over the years, in different houses I’ve lived in. The others were marginally effective compared to what I have now.

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Thanks for the input. Running any sort of conduit to my listening room is not going to be practical. If I ever have an opportunity to design and build a listening space I would likely do something like what you suggest.

:slight_smile:

What size conduit was used for your project?

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We may be talking past each other on this. I’m referring to the behind the wall conduit to house and route the triple THHN. Something like this

although I’d have to look up exactly what diameter I used.

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Oh, one more thing. First, don’t use your existing home subpanel. I’ll be blunt - if you want the best result, run a new 100A breaker from your main box outside (the one that feeds your home subpanel), using NM-B or equivalent, to a new dedicated subpanel just for your audio circuits. Place the new subpanel as close to your listening space as possible. You want two separate outlets? Use two separate 20A breakers. Basically, bypass everything in your home at the first possible location. Do it once. Do it (IMO) right.

2 Likes
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We’re on the same page.

I’ll bet braiding 10AWG solid THHN cable was fun.

:wink:

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Your distribution service must be different than most I have seen, most have a meter socket on the outside of the home and a main distribution service panel inside.

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I just learned yesterday from our electrician that when we got our 200A upgrade the “main” panel inside was wired as a sub-panel. Maybe this is how they do it now? There is a meter and a main disconnect outside the house now.

Prior to this the only thing that was outside was the meter. The service cabling came straight from the pole, connected to the meter then came straight to the panel inside.

So conceivably (???) I could run another circuit from outside to a dedicated sub-panel for audio. Not going to do that in this house…it’s just not practical. But if I ever get to plan for a listening room and it’s new construction then I will definitely go this route.

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Outside I have a main disconnect, a main breaker for the HVAC compressor, another breaker for something else that I can’t recall at the moment, and now the 100A breaker for the independent sound room subpanel. Apart from that last, this is how pretty much all recently (~30-40 years) built stand alone houses in this part of the country have been built.

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The nec has mandated an outside disconnect since 2020. I learned something new today thanks.

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I wonder if hurricanes has something to do with why Florida has been ahead of that mandate? Maybe having to do with having external access to power shutoff in an emergency.

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I’m pretty sure that is true, the nec mandated it so emergency response can have easy access to a power disconnect.