AC Power - two circuits better than one?

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.
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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.

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...

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?

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!

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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?
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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.