AudioNervosa
Electro Stimulation Ward => Signals and Noise => Power Cables => Topic started by: mfsoa on December 14, 2013, 12:57:14 PM
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As we need to have a window AC put on its own circuit, we are getting a sub-panel installed in the basement - system is on the first floor.
It just so happens that I should be able to position the panel directly below the system, making it easy to run multiple dedicated lines of maybe 4-8' each.
I was planning on running several lines, maybe 4 x 10A, but I read in one other thread here to just run a single 20A line to reduce possible ground problems.
Any thoughts? What would you run, 2 x 20A? 1 x 20A and 2 x 10A? My power requirements are typical of a wannabe audiophile.
-Mike
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Mike,
I ran 2 - 20A circuits when I finished the basement but I am only using a single circuit right now.
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Hi Mike! 2 x 20A would be my preference. You want to do 20A runs for audio because you get thicker wire inside the walls, that lowers wire resistance for lower impedance to the amps, allowing better damping on amps with undersized transformers. You can use 20A hospital grade outlets. But most electricians will only stock the single plug outlets for a 20A circuit, but you can replace it with a 20A Hubbell duplex on your own.
There's no such thing as 10A circuit, minimum now is 15A as a standard circuit. This would probably be enough for anything you would throw at it, but you don't get the 12ga thicker romex in the walls, you only get the 14ga standard wire. Since the labor is most of your cost, installing the thicker wire is worth it.
You can gang a couple duplexes together in a longer box if you want more outlets on each circuit, but mark which outlet comes first, you'll want to put your power amps on that one. :thumb:
The AC will put some noise on the audio circuits.
Ask the electrician to put both of your audio circuits on the same leg, the opposite leg of the AC circuit. 240V service is made from 2 legs of 120V running in opposing phases to create the 240 when added together. Audio system only needs 120V, so only one phase is needed. It will still work if some audio components are on one phase while other audio components are on the other phase, but [the internet] says that the sound is better when all audio components are on the same phase. The phase, or leg is determined by where the breakers are physically installed in the panel. The phase alternates with the vertical spaces in a column of the panel, and left/right side spaces are opposite phase.
Like this:
X O
O X
X O
O X
So you would put all of your audio circuit breakers on either all Os or all Xs. Put the AC circuit on the other phase.
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You can use 20A hospital grade outlets.
Yeah, forgot to mention that I ran hospital grade outlets all over the basement including the 15A circuits. I think I used Leviton ones though.
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I ran 2x 20A lines and used hospital-grade outlets but in the end, I'm only using a single plug from each so I could probably have gotten away with just a single line. I'm running 10 pc of equipment and the most draw is coming from the SET mono amps (I'm going by the heat put out). If I were using high watt, big draw amps or subs, the other line would most likely be needed - better to have the extra capacity in case my audio plans change.
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I think hospital grade duplex are rated for 20A. Most regular duplexes are only rated for 15A. So when you order a 20A line, if the electrician doesn't have a 20A rated duplex on his truck they will install a single plug outlet which is rated for 20A.
20A duplex has the T-Slot hole to accept a horizontal neutral blade designating 20A.
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You can install 15A receptacles on a 20A line, but there must be more than one... if there is only one receptacle then it must be 20A... you can get hospital grade receptacles in either 15 or 20A, from what I can tell the only difference is the t-slot cutout for the rotated plug on a 20A appliance.
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Yes, you are right Dave. It's counter intuitive to put a 15A outlet on 20A line, but the lack of a T-slot is what prevents a 15A outlet from supplying a 20A appliance which requires a 20A plug with horizontal neutral blade. Thanks.
Why must you put two 15s? Is it just because why else would you need a 20A breaker?
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Rich, That's just following code, and probably for the reason you stated.
If you were bringing in 2 dedicated lines, and the receptacles were relatively close to one another, you could alleviate the grounding issue by running a ground wire from the receptacle of one line to the other... I haven't tried this, don't know if it's up to code or not, but it would solve the issue of the grounds having to go all the way back to the panel before they are joined together and should reduce impedance of the grounds between one line and the other by quite a bit.
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You can install 15A receptacles on a 20A line, but there must be more than one... if there is only one receptacle then it must be 20A... you can get hospital grade receptacles in either 15 or 20A, from what I can tell the only difference is the t-slot cutout for the rotated plug on a 20A appliance.
Not sure what Dave is saying here, but some readers can take away the wrong idea that it is 'ok' to use a 15A outlet on a line with a 20A breaker...No, it is a code violation. THe line will have to be serviced with a 15A breaker to use 15A outlets.
It is ok to use 12Ga. wire with 15A breaker and outlets. And in fact most electricians use 12Ga. as the stock wiring for both 15A and 20A line circuits.
Edit. Sorry Guys, I was wrong, That's what you get from mixing solder lead vapor with the skunk in the bubble :lol:
crosswired brain cells.
As for the duel, I choose swords, nice and slow dead from 100 cuts. :D
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Rich, That's just following code, and probably for the reason you stated.
If you were bringing in 2 dedicated lines, and the receptacles were relatively close to one another, you could alleviate the grounding issue by running a ground wire from the receptacle of one line to the other... I haven't tried this, don't know if it's up to code or not, but it would solve the issue of the grounds having to go all the way back to the panel before they are joined together and should reduce impedance of the grounds between one line and the other by quite a bit.
Per Code: The safety ground cannot be jumpered between circuits at the receptacle end; the only place they can meet is at the main breaker box.
Per Code: A 20 amp circuit can be terminated with a single duplex 15 amp outlet, as one duplex outlet has 2 receptacles.
FWIW
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Acidjazz,
This means WAR! Safety Ground wires at 20 paces! :-P
-Paul
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pmkap, thanks for clarifying. :thumb:
I want a vid of the duel :)
edit: also, what that would mean to me is that more than one dedicated line isn't a good idea because of the grounding. One thing that might be possible is to run a larger wire/breaker and fuse down to 15 or 20A at the receptacle?
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If I was doing this I would use at least 2 - 15 amp circuits for regular stereo. I would put another 15 amp outlet in for mono blocks. Think about where the amps would go and put one behind each amp. This keeps power cord lengths shorter. So 3 maybe 4. All 10 gauge from the fuse box.
I am using a 240 balanced line and a 15 amp circuit atm.
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.....
edit: also, what that would mean to me is that more than one dedicated line isn't a good idea because of the grounding. One thing that might be possible is to run a larger wire/breaker and fuse down to 15 or 20A at the receptacle?
Personally, I'd put my money on Martin (AcidJazz). I've got him on bulk, but he's got me on speed....
The only way I know of for minimizing the potential for ground loops when using multiple lines/circuits that are a goodly distance from your main panel is to use a Main Lug / Sub-panel.
For example, one could run a 50amp circuit, with its own breaker, from your main breaker panel box to a sub-panel located adjacent to your audio room (or in a closet). From the sub-panel one would then put in 2 (or more, depending on the feeder circuit) 20 amp dedicated lines from the sub-panel to your close by outlets. This minimizes the round trip ground loop as however many dedicated circuits connect their safety ground together at the local sub-panel. Whether you would need a disconnect at the sub-panel or if the feeding breaker at the main panel would suffice, depends on local codes. [also note that if you're doing it yourself, not recommended, that the connection between safety ground and neutral, if its there in the sub-panel, must be removed, as you can only bond ground and neutral at the main panel, in almost all circumstances.]
FWIW
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Opps, I sometimes suffer from foot-in-mouth disEase. :lol:
YOu guys are right.
I blame my miscue on too much solder lead vapor.
Carry on!
PMK I choose swords...on guard! :lol:
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THe line will have to be serviced with a 15A breaker to use 15A outlets.
Edit. Sorry Guys, I was wrong,
I thought the same thing Martin! It is so unintuitive! Should put it in the "Strange, but True!" section... :)
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If anyone needs something a bit more substantial than average for your system, just let me know :lol: Thread reminded me of it for some reason...
250A 240V 5 zone computer controlled receptacle bank (custom greenhouse job I did some years ago)
(http://i99.photobucket.com/albums/l318/davec113/BlueFlowersBR/BUDSHOTS/The%20Build/DSC00760.jpg) (http://s99.photobucket.com/user/davec113/media/BlueFlowersBR/BUDSHOTS/The%20Build/DSC00760.jpg.html)
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Thanks for the tips, fellas.
The electrician would prefer to put the subpanel closest to the main panel but this is is at the far end of the basement from where the system lives above. I would prefer to have the subpanel under the system, requiring a long (60-70') run of the 240 V (or is it 220V?) line from the main panel to the subpanel.
For such long run, what gauge wire should I use? I assume copper only. The really fat copper gets pricey tho.
A long run to the subpanel = short runs to the system, which I'd prefer. I could then perhaps spring for the JPS in-wall.
Thanks again,
-Mike
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The subpanel under your system is preferable in minimizing potential ground loop issues. Are you planning on using both legs of the 240 (120vac-120vac) from the subpanel?, perhaps one leg for your AV equipment and the other leg for other uses to keep external noise out of your audio. If you're only going to use the one leg, just for powering your system, if within code, you could save by only running 1 of the 2 120vac legs and be sure to have the subpanel labeled as such so the next electrician dealing with it isn't totally flummoxed. 6 gauge solid core is indeed expensive. Lastly, I run my system off a single 20 amp circuit. No subpanels required, minimal potential for loops. But I also use multiple filter power conditioning that isolates components from each other.
I'm looking forward to your report(s) on how this investment in resources effect your system.
Regards,
Paul
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Excellent advice Paul. Good to see you posting and helping here.
charles
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Excellent advice Paul. Good to see you posting and helping here.
charles
Charles,
Are you implicitly chastising me for being a total prick on the other board? :rofl: If so, I admire your perceptiveness.
Have a great holiday!
Paul