Shielded dedicated line or not?

I got an offer for some apparently high-quality 9AWG mains wire that’s shielded with a relatively sparse copper mesh.
Paul advised me not to get a shielded line. However, since this is a sparser mesh and is connected to ground only at the panel, I wonder if it’d be a good idea - my other option would be to have twisted hot&neutral with a separate straight ground.
The guy who’s offering me this shielded wire says it’s totally better quality wire than standard 9AWG… (Well he IS selling it but it’s not like it earns him much, he’s a speaker builder)

I ran10AWG stranded wire Armoured Cable from my breaker panel into my living room. The Armour Cable is grounded on both ends by the breaker panel and the outlet box. Of course inside the AC cable, there are 3 insulated 10AWG stranded cables. No ground loop issues and I’m not using any conditioning or regenerators. I hear no noise with my ears close to the Tweeters as well.

Don’t know if that helps but it’s safe.

So it’s shielded cable? You mean the shield is grounded on both ends?

According to code here in the U.S. (& Canada for that matter. Any flexible or rigid tube Armoured Cable must be connected to GND on both ends.

I did a video on this :

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Ahh, so here the metal armour acts as shield for interference, or is it mainly for mechanical protection? Is the cable shielded? As in with a conductive braid?

No, MC cables only has a plastic wrapping that wraps around
the conductors.
This guy in the video really is doing a mickey mouse job with the junction box with the cable sticking through the wall. I would have come with the cable to the back of the box. Then you wouldn’t have the exposed MC cable showing. It’s also against code. Better yet, cut in a 2 gang cut in box and flush mount it.

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That’s the way the wiring was originally. I just used it as an entranceway for the second set of wire. I have two runs of Armoured cable going though the garage and into my living room. No way in hell was I gonna start punching holes in walls and running it inside the walls.

What’s Mickey Mouse about running and clamping down Armoured Cable ? I thought code says any exposed wire runs must be inside conduit or flexible Armoured Cable.

You should have seen the mess I had to clean up when we tore walls down and relocate and properly run wiring and outlets in our kitchen ! GFCI outlets above the counter with only a few parallel outlets running off of the GFCI outlets.

I said numerous times in the Video if you don’t know WTF you are doing, don’t try this sxxt at home and hire a licensed electrician.

The house had 70% ungrounded outlets (house built in 1966) before we closed on it (typical Phoenix, AZ range house of that era) that were as old as the house. I insisted that an electrician Ground all the outlets and add GFCI where necessary according to code.

I’ve been doing electrical house-wiring since I was in High School. Our Electrical Shop Teacher taught us Electrical Code in the mid 1980’s and also introduced us to Digital Logic Circuits later on. He had no permission from the School Board to teach DLC so the deal was, if we bought the protoboards, he’d provide the chips and wire.

It gave us two paths. Electronics Technology or Electrician/Electrical work. I went with Electronics, my friend who failed the Teachers Electrical class, went on to be a successful Electrician :slightly_smiling_face:.

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Okay, okay.

The question remains: (lightly) conductively shielded dedicated line, or not?
And to make a point, it’s 9AWG so the shield is relatively further…

The guy in the video is you? Sorry, no intention to offend or disrespect you in any way. Just thought the aesthetics could be better.
Maybe I don’t remember well or the code has change over the years, but I thought exposed MC is not allowed in living areas. But what do I know.
By the way, I’m a retired state licensed electrical contractor. Over the years I’ve seen it all. You did do a nice and safe job being a non electrician. I have to compliment you on that.

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If you use an armoured cable, the outer jacket is your shield. If you run wires inside a metal conduit, the conduit is the shield. Other cables with plastic or rubber covers can have a metal braid for shield. The ground is a separate wire.
I believe Paul said that power cords don’t need a shield since EMI don’t really have much effect on it. It’s the smaller signal wires you really need to shield.

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It’s the problem with interference induced onto the ground, I think.
It’s gonna contaminate everything if there’s junk on the ground.

Then you should consider star grounding.

https://resources.pcb.cadence.com/blog/2020-what-is-a-star-ground-layout-and-why-do-you-need-it

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You mean without regards to the actual safety grounding of the house nor the dedicated line?
I somewhat understand star grounding on the basis of components.
Just to clarify - isn’t this something I would do (if necessary) at the “small scale” that concerns individual pieces of gear?
If there’s a macro-scale (so to say…) version of star grounding that deals with the power line, I can’t say I’ve heard of it nor understand it.

Anyway, an update - I’m going with the 9AWG line with the relatively shallow copper mesh, which would be connected at the panel. All the talk of constricted sounding power cables due to the shielding too near - I believe it and the reason in simple terms is clear to me - EM wave constriction in too thin a waveguide. (Waveguide the correct term here? It sure guides waves…)
I doubt however that a kinda shallow braid over such a thick bundle of conductors could do harm. Might do some good though.

Anyone know to say if a good old ceramic fuse is better at the panel than one of those switch type ones?

I don’t know if having a metal sheath around a power cable helps or not, but I do have 2 Acoustic Zen Gargantua II’s where one has a shield and one don’t. I tested with a voltage tester to confirm. One beeps and lights up, the other doesn’t. I hear no difference between the 2 power cords. Some Hi End power cords have shields, some don’t like Kimber. Either kind sounds excellent with no problems.

I think it’s more important to keep noise out of the power cords is to separate the digital and analog circuits as computers and digital components can generate a lot of noise and feed back to the other components. And run dedicated ground wires to the panel board for each circuits.

I don’t know if a ceramic fuse would sound any better than a circuit breaker, but my thinking is it wouldn’t because of the resistance of the wire in the fuse, as a circuit breaker uses heat only to separate the contacts. And a circuit breaker is much easier to reset than finding a replacement fuse if the circuit blows.

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Thanks for the input.
When it comes to whether a shield helps, I’m sure it does when implemented properly.
There was this short paper on the measured noise rejection efficacy of having an L-N twisted pair with the GND running alonside, versus the ordinary bundle.
If I recall correctly, the twisted pair was up to several hundred times better at preventing unwanted induction.
It’s noteworthy that the conclusion was that all wiring in the house should be twisted like such for it to have proper benefit in practice - thus why I chose the lightweight braid shield.
If it was heavy shield, as in not really even see-through, I would lose sleep, haha.
The flow of mains electricity has (or more precisely is propagated by?) a fairly hefty EM field so I’m with Paul in that it needs sufficient space in the dielectric…
If we think of a power cord as an extension of the primary… Well, I wouldn’t go putting a conductive shield too close there. A high permeability shield for sure.

Have I learned anything?

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I think obsessed is more the word. :laughing:

Is the cable to your home shielded? Is it overhead or underground from the utility transformer? Normally any overhead secondary cable from the transformer is not shielded (and it’s not copper!) so it will act as a long antenna. If you share the transformer with your neighbours, noise from their 120/240 volt (approx) cabling and electric loads will come into your electrical system. To shield a portion of the wiring does not seem practical to me.

The nearest utility transformer is about 500m (0.3miles) away, wih overhead lines.
It’s shared by… Hm. Let’s say 10 other residences at the very most. I’d say less most of the year.
Unfortunately ours is the last home from that transformer. There’s one that’s closer, with certainly less usage but it feeds the wrong direction…
Utility transformers have a direction… Right?

There is no “direction” from a utility transformer. It provides a nominal voltage (+/-) based on the windings ratio, transformed from the higher primary voltage (perhaps 7.2 kV or 14.4 kV). The nominal voltage at your home varies/drops depending on the overall electric load of all the homes (which varies all the time), and depending on the wire size. Hence, the voltage at the transformer could be 125 volts and drop to 115 or 110 volts at your electric panel. I share a transformer with 2 other homes and years ago when my water pump turned on, I measured under 100 volts for a moment due to the current inrush. That did not meet the electric service standard so the utility had to install a larger transformer. If you want great sounding audio system, a power regenerator will provide a stable 120 volts with a high current capacity. When I finally could afford one, I was amazed at the improvement in the musical dynamics, the extra bass and so on.

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A regen for sure, when capital allows.

Until then… Isn’t it better to have thicker copper from the utility dashboard to the house panel, than the dedicated line’s thickness? It’s a 50m run of 9AWG atm, wouldn’t this already bottleneck the 9AWG line at such extra length length?