AC Power - two circuits better than one?


Reorganizing my system starting from the wall receptacles (rewiring is not a possibility) but quickly ran into a conundrum. Is it better to source power for my audio system from several different circuits or one dedicated circuit?

More info: I have three possible options. Two 15 amp circuits (1 shared with a couple of lights the other with several wall receptacles including a pc) & one dedicated 20 amp circuit (but with only one single duplex outlet). I have mono blocks, power amp, preamps, digital & analog audio sources, & digital HT gear.

Should I distribute my system across these three circuits or try & source them all from the single dedicated 20 amp outlet? If distribute, what kind of break down makes sense?
salmonsc
The one thing to avoid is to use both legs of the incoming 240V. To check for this (if using two separate wires from the breaker box, is to measure the A/C voltage from BOTH of the hot wires from the two outlets.
So you would have either:
Checking all four wires against each other:
#1 with #2 120V ... #3 with #2 120V
#3 with #4 120V ... #1 with #4 120V
#1 with #3 zero voltage ... #2 with #4 zero voltage
OR you might have one pair measuring 240V even though all the other measurements are 120 or zero.
IF you have a 240V in there with a possible combination.. That is bad. Most likely nothing will happen, BUT if one of you components develops a short, or is miswired, you could have a 240 volt surge through your stuff, both ruining a big pile of equipment, and hurting yourself.
So avoid two different legs of the incoming A/C.
Using an outlet with NO other stuff on it is the best. The 20 amp could be better if you have enough of a load that you are usingg a lot of a 15 amp curcuit. (If the A/C cord at the wall is HOT, you need a better cord, or bigger capacity wall amperage.
I have a ton of stuff on a 15 curcuit, and find it is OK. I used to use a 20 amp one, but that entailed running a ten guage extension cord 100 ft, and I decided to just stop using that.
With two monoblocks, I would use the 20 amp single..
(Another problem that could arise from using multiple outlets is hum from a differential in the grounding of the two outlets.)
But, if you have two 15 amps on the same leg, then try both ways and see.
(When I say the same leg, I do not mean the same wires from the breaker box, it is two separate sets of wires from the breaker, just avoid using two that are on different legs of the incoming 240 volts)
IF you do not have a voltmeter, you can cheat (but be careful!) wiring up a small 25 watt light bulb. if you have a 240v the light will burn out rather spectacularly with a big flash when it is connected to the 240 V.
If you are on the same leg, the bulb may light, or just not do so.
Thanks for the advice Elizabeth, but I still am not quite sure how to check that the circuits are on different legs. I should be checking that the voltage on any two of the circuits doesn't total 240V? I'm a little confused by how I would actually do that - measure one at a time or two simultaneously?
Salmonsc,

If the circuits are fed from the same leg you will measure zero volts from the hot slot contact of one branch circuit receptacle to the hot slot contact of another branch circuit receptacle. If you measure 240V between the two measured branch circuit hots, they are fed from opposite legs.

I doubt you will find that all 3 branch circuits are fed from the same leg. Might be though.... Good chance 2 will be. Use the dedicated 20 amp branch circuit as the starting reference point. Measure from the hot of the 20 amp dedicated circuit to each hot of the two convenience 15 amp branch circuits.

You can use a drop cord to extend one lead of the volt meter. Note the smaller length slot of the two slots is the hot conductor. You can verify by measuring from the smaller slot (hot) to the equipment ground (round hole) contact. You should measure 120V.
.
Jea48 said it MUCH better than I did.
(sorry)
Many thanks Elizabeth & Jea48, I will check this out tomorrow. Assuming I can find a second branch circuit fed from the same leg as the 20 amp circuit, I will likely connect the monoblocks (& possibly the power amp) to the 20 amp circuit & the sources to a 15 amp circuit. Does this make sense?
As predicted, apparently not all 3 branch circuits are on the same leg. Unfortunately, the configuration of outlets in the room on the same leg isn't exactly convenient. Hence my next question: If I keep all the audio components on a single leg (20amp & 15 amp), is it a major problem to have video equip (TV & DVR) on another leg - the only connection between the two systems is via HDMI routed through the preamp. I understand this isn't ideal but if they are attached to separate surge protection is it workable?
If this was me and rewiring is not an option, I would look into getting a power distribution center such as a PS Audio Premier and plugging into the one 20-A outlet and seeing if all my gear can be accommodated. It is always better, IMO, to limit the number of audio outlets to as few as practical to reduce ground loops and EMI/RFI.

If one power center isn't enough (monoblock amp draw, e.g.) then I would look to get another power center or an A/V grade power strip and plug it into the outlet without computers or motors on the circuit.

The advantage here is that you don't have to worry about phase leg anomalies (etc) because the power generators will scrub the power input.

But if rewiring is not an option due to cost, then my suggestion makes no economic sense because you can rewire for a lot less than the cost of one PS Audio Premier, let alone two.
Usually it is not problem to have video equipment on the same outlet, as most folks are not using both at the same time.
(Though I watch some Sunday football games with the sound off while listening to my stereo)
I have a huge pile of stuff on one 15 amp outlet, and do not have a problem.
IF I were you, I would put ALL the amplifiers/preamp/ receiver? on the 20. and everything else on the 15 and skip the last out of phase outlet.
I have all my amps/pre/receiver/Plasma from a Furman REF20i, and all my other stuff (digital) from a Monster 7000SS signature
Thanks again for your input folks! I will endeavor to load as much as I can onto the 20amp outlet & the remainder onto the 15amp outlet. The difficulty is just physical connection - too many things for too few outlets (in the wrong places!). At a certain point daisy-chaining power strips - & running long power cords - starts to get problematic. That's why I was considering connecting the TV & DVR into the out of phase 15amp outlet.

I was planning on connecting the audio gear via a Monster AV2000 SS & the HT gear via a Monster HD3650. I would prefer to connect the mono blocks & power amp directly to the 20amp circuit via PS Audio duets to avoid the power limitation problems of surge protection/conditioning...
Unfortunately, the configuration of outlets in the room on the same leg isn't exactly convenient.
12-12-10: Salmonsc

You could hire an electrician to move the circuit/s to a breaker space/s in the electrical panel so they would be on the same leg.

Cost?
It won't take an hour but that is usually the minimum charge.
Actually, I had an electrician in on Friday - but as I wrote in my original post, rewiring is not a possibility. It's a very old house & not mine.
You should use the 15 amp circuits for all your gear with no problem.The 20 amp cicuit was used for something that draws higher current most likely A/C,clothes dryer,etc.A 15 amp circuit is about 1700 watts,no way does your gear come close to that much.
Salmonsc: Thanks for this thread - I never realized this issue could arise. Without taking over your thread I would like to ask your respondents to comment on my situation - similar to yours.

I have 4 dedicated 20 amp circuits for the equipment including a pair of monos and an APC Power Conditioner for all the rest of the stuff. Circuits #1 and #3 are on one leg of the circuit breaker box and Circuits #2 and #4 are on the other leg of the circuit breaker box. The power conditioner is on Circuit #1 while the monos are on circuits #2 and #4 respectively. Have I created a potential problem for myself? Perhaps the monos should be both plugged into circuit #3?
Circuits #1 and #3 are on one leg of the circuit breaker box and Circuits #2 and #4 are on the other leg of the circuit breaker box.
12-13-10: Puerto

Puerto,

Most if not all electrical panels made in, at least, the last 25 years have the odd number breaker space on the left hand side of the panel and the even numbers on the right hand side.

If that is the case for your panel then 1 & 2 are connected to Line 1 (leg). 3 & 4 are connected to Line 2.
You can verify at the receptacles with a volt meter. (See above post.)

Line 1 and line 2 alternate down each side of the panel.

Are you sure you have (4) dedicated branch circuits an not (4) separate circuits?

Dedicated branch circuits have their own hot, neutral, and equipment grounding conductor.

Where as for a single phase electrical panel found in most houses two separate branch circuits can share a neutral and equipment ground. In this case the two hot conductors must be install on opposite Lines, (legs).

Did you install the 4 circuits or did you hire an electrician? Were 4 dedicated branch circuits installed?

Example, four 12-2 W/ground Romex (NM-B) or two 12-3 W/grd Romex?
Actually, I had an electrician in on Friday - but as I wrote in my original post, rewiring is not a possibility. It's a very old house & not mine.
12-12-10: Salmonsc

Salmonsc,

It really would not technically be considered rewiring. All that would be done would be to move a wire from one breaker space in the electrical panel to another space.

12-12-10: Elizabeth
Usually it is not problem to have video equipment on the same outlet, as most folks are not using both at the same time.
(Though I watch some Sunday football games with the sound off while listening to my stereo)
I have a huge pile of stuff on one 15 amp outlet, and do not have a problem.
IF I were you, I would put ALL the amplifiers/preamp/ receiver? on the 20. and everything else on the 15 and skip the last out of phase outlet.

Sounds like a good idea...... No doubt the 20 amp dedicated circuit will supply the best clean power possible. The 15 amp convenience outlet circuit the least....
Jea48 Actually I have 4 separate circuits (not dedicated branch circuits as you described). I live in Mexico and had an electrician do the work. I would assume that circuits 1 & 3 would be on leg 1 because they are odd numbers while circuits 2 & 4 would be on leg 2. Here they use multi-strand wire, not romex so I had them pull three 12 gauge multi-strand wires from each respective breaker to the corresponding receptacle. The three lines were for hot/neutral/ground. The ground is grounded directly to the (USA) standard 200 amp panel which, in turn, is grounded to 8' of copper rod with #8 gauge wire.
I would assume that circuits 1 & 3 would be on leg 1 because they are odd numbers while circuits 2 & 4 would be on leg 2.
12-13-10: Puerto

Is the power that feeds your home 120/240Vac?
If yes do you have any equipment or appliances that use 240V? If yes check your panel you should see 2 pole breakers for the 240V equipment. (2 pole breaker takes two spaces.)

If that is the case then every other space down each side of the panel is the other Line, leg.

Line
L1 (1)......(2) L1
L2 (3)......(4) L2
L1 (5)......(6) L1
L2 (7)......(8) L2
ect.

Note: Twin breakers (slim) changes the ball game for the above example.
>>>>>>>>

What's the weather like?
COLD and snowy here in the Midwest!

.
Jea48 Thanks, I don't want to get into the details but it's not possible - the outlet that's most convenient is part of a circuit that extends upstairs. In any event, it's not my house so reorganizing circuits on the breaker just isn't an option. I am going to load up the 20amp circuit as much as possible & divert the remainder to the cleanest 15amp circuit.
Jea48: We do have 120/240 servicing the house. Our A/C units use 240V with 2 pole breakers. Thank you for that input, now I can figure out how to get the pair of monos and the APC power conditioner/battery back-up on the same leg.

Weather here is chilly at night in the low 60's and gets into the mid 80's during the day! It is definitely "sweater weather" once the sun gets low in the sky.

Thanks again to Salmonsc for the informative thread. I hope others can benefit from the comments above.
Jea48: As a follow-up, you are correct, I checked voltages and circuits 1 & 2 are one one leg while circuits 3 & 4 are on the other leg. The question now is what is the best configuration for plugging in. I have three power cords (pair of monos and the APC) that must be plugged in. Right now I have the monos on circuits 3 & 4 (same leg) and the APC on circuit 1 (other leg). Is there a better way? I figure that the APC is so incredibly sensitive that having it on the opposite leg would probably be OK. Each circuit is 20 amp with only one receptacle.
salmonsc: FWIW, I took the advice of Jea48 and switched the wires on one pair of breakers in the main panel box and that action put all of my equipment on one leg of the incoming power. It took about 10 minutes. You only have to switch the hot leads, not the neutral or ground wires because they are secured to common bars within your box.

Thanks for your thread and thanks to Elizabeth and Jea48 for their useful input.

Just thought you should know that switching circuits is not all that difficult. Just be sure to turn the WHOLE BOX OFF before making any changes.
I took the advice of Jea48 and switched the wires on one pair of breakers in the main panel box and that action put all of my equipment on one leg of the incoming power.
12-17-10:Puerto

Puerto,

Not sure exactly what you did..... With a 3 wire multi conductor circuit, (2 hot conductors, 1 neutral conductor), you cannot put both hot conductors on the same leg. They have to be on opposite legs.

With a multi conductor branch circuit only the unbalanced load returns to the source on the neutral conductor.

Example: If two identical loads were connected to each hot to neutral of, say, 5 amps each zero amps would return on the neutral conductor. The two loads would be in series with one another.

Example: If the two loads were 15 amps each, again zero amps would return on the neutral conductor to the source.
But if both hots are connected to the same leg, (two 20 amp breakers), 30 amps would return on the neutral.... That's a no no......

http://openbookproject.net//electricCircuits/AC/AC_10.html#xtocid139960
Now you have me worried. I simply switched the hot lead from one breaker on Leg 2 to a breaker on Leg 1 ( and vice versa). The breakers only have one wire each connected to them so the "living room" circuit (formerly on leg 1) is now on leg 2 and the "stereo circuit" (formerly on leg 2) is now on leg 1 where the "living room" circuit used to be. It was a two wire operation. I left the neutral and ground wires where they were. There was no other place to move them to. Everything seems to be working just fine. So have I screwed up? These circuits have three wires each - Hot, Neutral and Ground. I am not following what you mean by two hot conductors on each circuit.
What you did is correct. That is 2 wire with ground not 3 wire with ground!
Yogiboy: Whew! Thanks - I thought as much but began to doubt myself after reading Jea48s post. He is obviously much more versed in this stuff than I am. You probably are too!
These circuits have three wires each - Hot, Neutral and Ground.
12-18-10: Puerto

Puerto,

If that is the case then you have 4 dedicated circuits.....
Each circuit has its own hot, neutral, and equipment ground.

Each of the (4) duplex receptacle has its own hot, neutral, and equipment ground conductors.

Total numbers of wires from the electrical panel to the audio equipment receptacles:
(4) hot conductors
(4) neutral conductors
(4) equipment grounding conductors

Correct?
.
Yep, that's correct on all counts!
I was actually just discussing this issue with my local audio store. I'm in the middle of building my home theatre. 3 mc 501's in the front. The dealer recommended i run three seperate 15amp lines from the box using 10 guage wire. He added that this would reduce noise pollution and create better over all sound to my 501's. He also said that i should run a seperate 15amp circuit with the 10 guage wire for the rest of the gear rack which is placed in back of the room. Can anyone help me,, will i really b safe and happy doing this?
Louislovesemy,

Sounds good except use 20 amp breakers instead of 15 amp.
Most audio grade receptacles are 20 amp. (NEMA 5-20R). Technically per NEC code a 20 amp receptacle can not be installed on a 15 amp branch circuit.
I don't know if I will go so far as to say MOST audio grade receptacles are 20A. :-) The only 20A receptacle Oyaide makes is the R-1. All their other models are 15A. Isoclean only makes 15A receptacles. The other manufacturers, PS Audio, Wattgate, Furutech, Acme, etc. make 15A and 20A receptacles in more or less equal quantities.
Gbart,

If you ran #10 awg wire would you terminate the wire on a 15 amp breaker? If so why?

If Louislovesemy uses 20 amp breakers, as you are aware, he can install 15 or 20 amp duplex recepts on the branch circuit. Why not install the max allowed branch circuit overcurrent device for two or more 15 amp recepts or a 20 amp recept/s.