Mains wiring question for the audiophile electricians

On3s&Z3r0s

A recent thread on dedicated circuits got me thinking I should be paying more attention to the circuit my 2-channel system is on. I live in a 60 year old house, and I gutted and re-wired the basement so there are dedicated circuits for the HT but my 2-channel rig is on original wiring in an upper story wired through the attic.

The convenient outlet up there is on a circuit shared by a bunch of other stuff, no motors (unless someone is using a vacuum cleaner) but a lot of lights. There's another circuit up there that is almost completely un-used. There are only two outlets on it. There used to be more when it was serving part of the kitchen too, but we remodeled the kitchen shortly after we bought and the contractors ran new circuits for that work.

So, I was thinking it would be pretty simple to get up into the attic and T a new run of cable into the circuit with 2 outlets to put another outlet convenient to the 2-channel rig. It seems pretty clear-cut up to that point, but the other issues with these circuits are: 1) they are ungrounded, and 2) they share a neutral.

I'm not too concerned about the grounding because I like to lift the ground on my amp anyway. For the other audio equipment I have a surge protector that uses the ground on the coax from the cable distribution system, and I have a pretty beefy whole-house surge protector so I feel like that's enough protection.

I don't really understand the implications of the shared neutral. My instinct is that the neutral shouldn't matter and the big win will come from getting the audio gear onto a circuit with less load/noise on the hot side. But if that's wrong and there's no real benefit if they still share a neutral then I guess I'm back to running an entirely new circuit. A completely new grounded circuit would obviously be ideal, but it wouldn't be easy to get the cable from the basement service panel to the attic, which is what has kept me from doing this so far.

If anyone has run into similar old wiring or has any other ideas it would be greatly appreciated, thanks!

michael1947

Best bet is to run a 12 ga. romex back to your service panel and run a 20 circuit...period. All else is just a band-aid and likely to land you in trouble. Talk to your municipal electrical inspector and get his/her opinion before you start.

On3s&Z3r0s

Thanks, and I do get that a new cable run is the right way to do it. But I'm not sure I could use the old 12/3 to pull two new 12/2's through to the attic without messing something up, but I think that would be what I would have to try because getting new cable in the walls would require a lot of blind drilling in a fairly compact space that is full of cable.

Also, I sure this will draw some fire, but I don't think I'd get an inspection just for adding an outlet. I did the full inspection thing when re-wiring the basement and went way above and beyond in following the NEC so I feel like I understand what they look for and would be concerned about. They're really good and accommodating here in Seattle, but that process is still a big headache just for adding an outlet. Mostly I'm curious about the implications of either option from an audio perspective as I feel pretty confident I could re-use the existing wiring without any danger to people or property. Again, the circuit I want to add to used to have several other kitchen outlets on it, which had to be upgraded to grounded wiring per code when that remodeling was done.

Speedskater

So the old cables are 12/3 and 12/2 Romex?(NM) but minus safety ground(EGC)?
Are you sure that they are copper and not aluminum?
Back then they did so strange things, like using a Neutral from one circuit and a Hot from another.
Why not borrow power from the home theater?

Systems

I know you probably already know, but it is not a dedicated line unless it is wired directly to the breaker box.
I do not completely understand from text on a page, (not the best idea to get electrical wiring advice on a forum), but you might consider "fishing" a new romex wire to the attic from an existing wire currently in wall (your current 2 ch receptacle).
Simply add a small rope to the fish bundle before you pull it, so you can pull the original wire back down.

Systems

Depending on how high your receptacles are from the floor, you can use a cheapo fishing rod (8 footer or so) to push wire to the attic, or from the attic also (with the eyelets removed).
I keep one on hand I bought at a garage sale for $5 for fishing speaker wires and such to the attic, the cheaper the pole the better (more flexible).:cheesygrin:
It all depends naturally if you interior walls are insulated (mine ARE for acoustic reasons).
I have pretty much completely gutted my house and put new everything in it (insulation, drywall, ect).
So I had the advantage of "planning" my HT and 2 ch. dedicated lines.

The cryoed 10 ga romex that VH Audio sells is very, very good, and I prefer it over my basic 12 ga dedicated line I use for the HT.
Pretty pricey but VERY good power wire, and worth every penny IMHO.

pdxfj

Not likely you would be able to use the old wire as a pull since it's usually stapled just above the receptacle box and near the top plate of the wall. You might be able to pull new wire through the staples if you used round romex but there's a chance to tear things on the staples.

My house is of a similar age and the original wiring is all copper. Most of it is 12awg, but is the old cloth covered wire.

Systems

pdxfj wrote: »

Not likely you would be able to use the old wire as a pull since it's usually stapled just above the receptacle box and near the top plate of the wall. You might be able to pull new wire through the staples if you used round romex but there's a chance to tear things on the staples.

My house is of a similar age and the original wiring is all copper. Most of it is 12awg, but is the old cloth covered wire.

If so, the fishing pole may come in handy.
You can fish down from the attic with the advantage of seeing where the original wire comes out in the attic.

I know what you are saying, and if there are cross members between studs for some reason, then you are screwed also.

Worth a try though, no NEC 60 years ago.:cheesygrin:

disneyjoe7

Is this old wiring Knot and Tube stuff? If not and used BX cabling the old metal flex stuff that is the ground.

SCompRacer

You got some good advice/concerns made.

The rule of a shared neutral is both legs of the 120 absolutely positively have to be on opposite buses. To break it down, you have two separate 120 lines/phases in the box. In order to share a neutral, you can't have both hots on the same leg/phase of 120 or the neutral will see the combined amperage of both circuits. Bad things can happen like that. You have to know your way around the breaker box to make sure you are not on the same bus with the hots when sharing a neutral.

Systems

I am just scared to give particular "wiring advice" to anyone about 120v stuff (it is deadly business, not to mention the fire hazard).
That said, you might do a search concerning the neutral wire sharing the ground (polarized 2 prong plugs), and that might answer some questions concerning the "ground wire".

SCompRacer

Just wanted to add some things. There are rules for electrical and for good reason. Pipe (conduit) has fill rules. You just can't stuff it full with any gauge wire you want so they share a neutral to meet those fill rules. Also there are box fill formulas for how many wires and devices can be in a box and you size the box accordingly. Maybe you can do the work yourself, but you should research how to do it the proper way. It's just not as simple as just running and connecting wires.

SCompRacer

pepster wrote: »

I am just scared to give particular "wiring advice" to anyone about 120v stuff ....

10-4. But this is info he can freely find on the internet. Now if I gave him the breaker rule of where is share, that would be TMI. IMO anyway.

And I would always run and connect a ground.

Systems

SCompRacer wrote: »

10-4. But this is info he can freely find on the internet. Now if I gave him the breaker rule of where is share, that would be TMI.

Having talked with you on several occasions and knowing your knowledge first hand, no doubt I would feel more comfortable with your advice.

That said, some of the "NOOBS" on this forum offering advice, not so much!:redface:
I basically would recommend to NOT take advice PERIOD when it comes to wiring advice, unless it is from a Certified electrician.
You might think it is expensive (to the OP), but it is some DAMN CHEAP INSURANCE in the long run!

SCompRacer

I like the trust like love needs to be reaffirmed rule myself. Get confirmation.

The thing is some folks will go ahead regardless of what you do and don't tell them. At least if you tell them the right way, and the why and what can happen if you don't, it may save them from going the wrong way.

Systems

SCompRacer wrote: »

I like the trust like love needs to be reaffirmed rule myself. Get confirmation.

The thing is some folks will go ahead regardless of what you do and don't tell them. At least if you tell them the right way, and the why and what can happen if you don't, it may save them from going the wrong way.

Very true!:cheesygrin:
Plus, if you wire a "true" dedicated line, it is safer, with less room for "error" than "T'ing off" an existing line.
Alot safer to run a single receptacle off a single run of wire directly to the breaker box, than it is to run off an existing "leg" with other "legs" involved.
Simple indeed, and the "audio" benefits will far out weigh the "splice" method.:cheesygrin:

SCompRacer

pepster wrote: »

Very true!:cheesygrin:
Plus, if you wire a "true" dedicated line, it is safer, with less room for "error" than "T'ing off" an existing line.
Alot safer to run a single receptacle off a single run of wire directly to the breaker box, than it is to run off an existing "leg" with other "legs" running off of it.
Simple indeed, and the "audio" benefits will far out weigh the "T" method.:cheesygrin:

Wait, you mean it ain't like water? I need water so I'll just tap into this pipe here and get it.:eek::cheesygrin:

Funny true story...well not to the wife anyway. Our first house, a post war home. Knob and tube with some BX here and there. Metal cabinets made in nearby Geneva hanging in the kitchen. The wife tells me she gets a bad shock if she touches the cabinets with her hands on the sink. I'm like oh, yeah, sure, so I stick my hand in the water and touch the cabinet. YOWSA! She ain't lyin. No ground to the outlet/light switch box, hot wire touching box from outlet, metal outlet cover touching metal cabinets.

Systems

michael1947 wrote: »

Best bet is to run a 12 ga. romex back to your service panel and run a 20 circuit...period. All else is just a band-aid and likely to land you in trouble. Talk to your municipal electrical inspector and get his/her opinion before you start.

+1:cheesygrin:

And I would always run and connect a ground.

+1 for sure, REGARDLESS!:cheesygrin:

On3s&Z3r0s

Wow... that provoked a bunch of discussion! To address some of the questions mentioned...

The cable from the service panel to the attic is a 12ga romex-type thing with a tarred woven cloth outer layer and three insulated conductors (red, black, and white, no ground wire). And they are definitely copper and there's no knob and tube in the house. The red and black hot wires are on opposite busses, so that should be ok. Apparently sharing a neutral like this was pretty common back in the day.

The basement's finished now so bringing anything else up through there is definitely not going to work. I should have run some extra circuits and tried to get them up to the upstairs living area, but I was zeroed in on the HT and was suffering from a bit of remodel fatigue. Oh well... hindsight. If I was going to pull new wire, I'd try to get new romex up through the existing staples from the basement service panel to the attic, but I am worried about tearing the insulation. If I try to go for a whole new run I'd have to put new holes in the framing top/bottom plates and get past the fiberglass insulation.

Once new cable is in the attic, I should be golden, but getting it there is the trick. Still it sounds like the consensus is anything short of a real dedicated circuit isn't worth the effort. Even if I take the other outlets off the circuit I want to use there will be at least the one splice and the shared neutral.

In all of this the thing that really makes me crazy is the fact that without buying an old crapshack and tearing out the walls there is almost no way to get good wiring in a house. Maybe it's just this market but my wife and I have been checking out some (for us) fairly pricey real estate and we still can't find anything with a decent media room and semi-decent high and low voltage wiring. Apparently now even home builders want everyone just to consume all their audio and video on their iPads.