2. misc-audio
  3. 151779-122613

Dedicated Power Line Project

I’m going to be adding a dedicated AC line to feed my audio system. Currently, the system is fed by a 75 foot run of 14 gauge romex that is likely daisy chained a few times in the wall between outlets. Needless to say when I turn the volume up, dynamics suffer and the overall sound quality is much less than I know my system is capable of. At louder volumes, bass notes will make the lamps dim and if I go louder, it seems like the system struggles and the bass notes get rounded off or sound “fuzzy.” My calculations tell me that with 75 feet of 14g romex, the voltage at the end of the line could be dropping by 5-10 volts, maybe more, during transient peaks. What I think is happening is that the power amps’ power supply caps are draining and there isn’t enough current to recharge them quickly enough and the amps start to draw directly from the AC line which causes a large voltage drop. 

Initially I was looking at a 10 gauge or 12 gauge line with a 20 amp breaker. After running the numbers, even a 10 gauge run could see some significant voltage sag at 75 feet during transients. At that point I considered 8 gauge, but the problem with that is that no electrical outlets will accept anything larger than 10 gauge, so I’ll have to do something fancy like place a junction box and step down to 10 gauge at the breaker panel and just before the outlet. Then I thought if I’m going to that much trouble with an 8 gauge, why not run 6 gauge? My calcs tell me 6 gauge could have a volt or two less variance than an 8 gauge and it wouldn’t be much more cost. So as of now, the plan is to run a 6/2 solid core romex line and run all the equipment of that. (I could run another line for the front end in the future but that isn’t the plan right now).  I have a few questions if anyone would be so kind to reply:

1) Are there any foreseeable issues with running “too large” a power line? I’m not sure if it’s accurate, but I’ve heard that large gauge is good for bass and small gauge is good for treble. Since I’ll be running everything (including the low current draw components like sources, preamps, etc) off this one line, is there any chance I’ll change the sound signature in a negative way?

2) What is better? In-wall romex or THHN inside a grounded conduit? I’m leaning towards romex because my gut tells me having the wire surrounded by something could hinder transients or hurt clarity but I’m not sure that’s accurate - that may just be from my personal experience with low level signal cables where too much insulation can be a bad thing. 
3) Are there any other “gotchas” that you can think of?

I’ve read the MSB Technology article and I’m subscribing to that theory which is this in a nutshell:

“It is the subject and goal of this paper. The gauge of the wire is FAR MORE IMPORTANT than the fact that the line is “dedicated”. The subject of this paper works on the theory that the varying musical demands of your amplifier are actually modulating the incoming power line, divorced from the utility (power company) by some resistance (12 or 14 gauge wall wiring at some length from the breaker panel has too much resistance for audio purposes).”

Thank you and wish me luck!
128x128mkgus
roberttcan
248 posts
 
Had a discussion about this on another thread, talking about any code / electrician issues.  When I had my runs put in, I had a tandem breaker that allowed two breakers on the same phase with a handle-tie. Not sure those exist any more. I went looking last night. I could not find anything. I found youtube videos of people installing that way (and not a switched/un-switched) but two separate feeds. Typically for a kitchen it is split phase -- two live, 1 neutral with a dual breaker.

If you can't get a dual breaker, single phase, with a handle tie, so that you can turn both of them off at the same time, they you are probably better off having two outlets really close to each other and tie the grounds together between them. Your code likely requires that if you have multiple live conductors into the same j-box, then they must be able to be turned off all at once.

Had a good laugh about the wires nest you are dealing with. I once had a house built in the early 60's when babies were still a booming and housing was needed and quick. There was no GFI in the powder room so I added one, assuming the wire that continued was for the ceiling light. Popped the GFI once. Bathroom light stayed on. Kitchen light went out. Garage light went out. Outdoor outlet went out ... you get the picture :-)
Post removed 
emailists
923 posts
 
I want to do a single run of 10 gauge from my breaker and instead of terminating in an outlet, i’d like it to be a 20 amp IEC I can plug directly into my Niagara power conditioner.

i know this may not be up to code. Any thoughts? This would eliminate some connections. With the Niagara it’s suggested to only have 1 AC line.

Too bad someone doesn’t make a high grade breaker switch. I’d like to try some contact enhancement on the breaker blades before inserting.

Any thoughts about which 10 gauge might be best? I know there’s is at least 1 in wall cable on the market for many years.


jea48
4,408 posts
 
@emailists

I assume you live in the US. My post only applies if you live in the US.

If you use Romex, (Romex is a Trade Name for NM sheathed cable), it is not designed or manufactured, or UL Listed, for use as you would like to do as basically a power cord extending from the wall electrical box. I only point that out so you know what most likely the electrical governing body in your area allows. (The AHJ, Authority Having Jurisdiction.)

With that out of the way.

Solid core #10 copper wire is pretty stiff and resists bending. Care would need to be taken when/if there is any bending at the IEC female connector. Any movements can, will, cause the tightness of the #10 solid wire to the mechanical lug terminations of the IEC connector to loosen. (It’s just the nature of a solid wire terminated in a mechanical lug). The only way to maintain a tight secure connection would be to solder the wire to the mechanical lug connection after mechanically tightening the connection first.

IF you want to meet electrical safety codes in your area you could cut/remove the plug off a good quality after market power cord and hard wire the conductors from the cord to the #10 solid copper branch circuit wires in the electrical wall box. Use spring wire electrical connectors. Nothing in the NEC Prohibits it providing the conductors in the power cord are rated for the ampacity of the branch circuit breaker.

You would need to install an extension box to the flush electrical wall box. You would need to install an approved strain relief cord connector to connect the power cord to the extension box.

Last but not least I would highly recommend you hire an electrician to do the job. He/she will know what is required/allowed by the AHJ in your area.

Example of a spring wire electrical connector.
https://www.homedepot.com/p/Ideal-Twister-Wire-Connectors-341-Tan-100-Per-Package-30-341P/202894284?...


Post removed 
More to discover