Dedicated circuits

I used 30 amp breakers because a few people said they give more headroom.

...another audiophile myth.

Most audiophiles don’t realize that standard (non AFCI or GFCI) circuit breakers are mainly there for short circuits, and won’t trip on in-rush current (or momentary speaker amp demands of high current). 15 amp breakers will easily intermittently pass peaks of 30 and 40 amps (and more if needed), because that’s what a typical refrigerator or air conditioner pulls when it starts up (it’s called in-rush current). A 20 amp breaker with 10 or 12 AWG wiring (14 AWG with a 15 amp breaker will be fine too), with a decent wall outlet, is all that’s needed. An isolated or dedicated ground is an added plus.

@immatthewj 

did the work boxes in between them and the outlets degrade them and does it affect them that each as two other outlets that are not being used?

I know some audiophiles really like to dissect every morsel of an AC circuit for audio, but in your case, I wouldn't sweat it. IMO, they're still considered dedicated circuits. Some with golden ears may not agree with that, but that's my opinion. 

Posting this from another thread I contributed to, and I realize some won’t be able to technically grasp what I’m discussing here:

For decades I have read about how many audiophiles have wanted to establish dedicated large gauge wired circuits with hundred dollar wall outlets, or power conditioning, to provide every milliamp of power available from their AC service to their speaker amps. I’m all for that, as I do the same. I get that. What I have a hard time understanding is that, IMO, it’s most times already there, without spending thousands of dollars on power conditioning and heavy gauge wiring. As I continue on, feel free to tell me what I’m missing here, and I’ll try to understand.

I think I know a little about AC for audio, so let me try to convey my thoughts here. First off, I hope everyone here is familiar with in-rush current. For those that aren’t, this is a momentary need for a large amount of current when an inductive device turns ON (for example, a refrigerator, dehumidifier, or air conditioner, etc.). Many times these in-rush values are in the 30-40 amp range, being pulled from non-dedicated 15 or 20 amp circuits (ie, there are other electrical devices on the same circuits). When this in-rush current takes place, not only are these spikes ignored by typical home circuit breakers, but the in-rush amps are almost always delivered on typical 15 and 20 amp wiring and circuits. If the wiring or circuit breaker wasn’t able to momentarily deliver this high current, your refrigerator, dehumidifier or air conditioner wouldn’t turn ON. IMO, momentary peak amplifier current draw could also be considered in-rush current.

I have an ammeter that is able to measure in-rush current (many ammeters aren’t capable of that). Since the conversation is revolving around improving home wiring for audio systems, I think this is the first time I ever placed my ammeter (set for measuring in-rush current) on my main audio system amplifier AC feed, while playing the passage of cannons on Telarc’s Tchaikovsky 1812 Overture CD (where they warn you that speaker damage can occur if you’re not careful when playing that passage in the song).

The ammeter was clamped on to the AC feed that provides power to my three Crown Com-Tech 400 Amplifiers (which are rated at 220 watts per ch. into 8 ohms). This particular system (I have a few in my house) is a tri-amped system, with an active 3-way crossover. The ammeter was only attached to the amplifier power feed. The circuit for these amplifiers is a dedicated one, with a 10 AWG 15’ cable running from the circuit breaker box, connected to a 15 amp circuit breaker in the load center. The 10 AWG terminates (with correctly torqued AlumiConn wire connectors/nuts) to a Tripp Lite Isobar Ultra surge protector. To soften the in-rush to the amplifiers during turn-on, I also employ a 10 amp rated variable autotransformer (aka variac), fed from the Tripp Lite Isobar Ultra.

So what I found was that when I initially turn ON the power switch on the autotransformer (without applying power to the power amps), an in-rush of 10. 3 amps occurred (that value is not always consistent, depending upon how recently the autotransormer was powered up, as it stores energy for a short period of time). After clearing that figure, I applied 120 volts to the amplifiers. As all three amplifiers sensed this voltage, they turned ON. The total in-rush current of these three amplifiers turning ON was 15.32 amps. Clearing the ammeter reading, I then played the cannons passage on the Telarc CD. I’m not sure if you’ve ever heard this CD (Telarc 80041), but when the LP came out (I have that too), it was monumental, as it was one of the few recordings that was able to record these extremely loud cannons, and transfer it to vinyl (later to CD). If my amplifiers were ever going to draw peak power, it would definitely be while playing these cannons. So with my speakers blaring, the peak power consumed by all 3 amplifiers during this passage was only 1.85 amps. I admit, I expected a value that was going to be higher, for the amount of bass that my 15" bass drivers produced.

So from my POV, your home circuits are already able to deliver lots of peak amperage when needed. Improving on that I get, but I’m not sure there really is a need for some, when peak power is probably already there when needed.

Recording of October 1979: The Telarc 1812 Overture

What is resistive load appliance? What is inductive load appliance?

@bigtwin 

Thank you for verification of my comments. Sadly it won't make much difference on this forum.

I realize that, but sometimes I like to give it another try. It's also all about educating one on the subject too. I'm still learning myself, but like to sometimes pass along what I have learned.

@mesch

Does anyone know of an amplifier that would require greater than a 15 amp curcuit? By this I mean one that even for a mil sec would draw 15 amps?

Only an in-rush current ammeter will provide this true information. If you don’t own one, you’ll never know for sure, even by reading the ratings specs of the amplifier itself. The amperage draw of an amplifier under question will vary depending on a) voltage available to the amplifier (in the US, 120 volts should be the goal) b) minimum current requirement of the amplifier c) amplifier operating with load (speakers being used) d) material being played through amplifier e) at what volume level amplifier is driven.

@immatthewj

Isn’t one of the selling points of a dedicated circuits that other loads are eliminated which would dirty up the power to your audio components? Not necessarily that you have more current available, but "better" current?

There’s plenty of arguments and discussions to go around. Power conditioners aside, the basic requirement or need is the ability to provide a path of least resistance for AC power transfer from your circuit breaker box to your amplifier(s). How you accomplish that is up to you or your electrician. It is most times accomplished via dedicated AC circuits, with no other appliances or devices on them. That keeps them "clean" and able to deliver the maximum amount of current and voltage needed. Over-sizing can increase this capability.

Not so for audio equipment power transformers. If voltage drops so does current as well as wattage, (VA)...  In the case of a power amplifier lower wattage, lower power...

Thank you.

@8th-note

You’re definitely on the right track, and probably more knowledgeable than most. When planning for audio AC circuits, it’s best when you can calculate your amperage capacity needs (in advance if possible). When it comes to audio needs, metering definitely helps in this area, with a knowledge of electricity as well. Establishing four dedicated 20 amp circuits for one’s audio system may be considered overkill for some, but may be a requirement for others. Yes, when lights are dimming when playing your system, there is some kind of starvation taking place, and in need of an inspection, improvement and probably upgrading.

I don’t claim to know everything, but I’m at least very familiar with grounding (for lightning especially), bonding, and wiring current capacity. I would agree with you on voltage drop for long distances of wiring. Those voltage-drop tables can easily be found on the internet, but probably not necessary in the home environment. Many audio-enthusiasts tend to favor delivering AC to their amplifiers via 10 AWG (as I too do the same, and have implemented it as well), but many electricians may not want to provide that for you, as I believe it doesn’t typically pass code (10 AWG on a 15 or 20 amp circuit breaker). I think someday someone needs to update the code for this application, as they have in the past with/for balanced AC power. It’s very easy to go to extremes when providing AC power for audio systems, but sometimes it’s simply not always necessary.

Do We Need Hospital-Grade Receptacles?

What exactly does "Hospital Grade" mean?

One topic that doesn’t get discussed much is available voltage. The rule of thumb is that what voltage can’t accomplish, current will (I know I’m probably getting a bit technical here). So let’s take that USA goal of providing 120 volts at an AC outlet, and you are measuring or only providing 115 volts (this can sometimes take place during hot air conditioning days in your neighborhood or building). Your amplifier could in reality pull more amps on peaks (compared to providing it 120 volts), due to the fact that you’re providing a lower AC voltage to it. This is when voltage drop becomes part of the equation. I guarantee that in most situations this won’t ever be a problem, but it is something to consider, especially with longer runs of AC wiring to the outlet from the circuit breaker box (technically called load centers). Again, this is normally not a big concern in almost all installations, except for some, but at the same time, it is worth noting. Here are a few examples of voltage drop charts:

Cerrowire Voltage Drop Chart

Voltage Drop Chart

@bigtwin

If a train leaves New York travelling at 60 MPH, and a Hot Air Balloon can accend at a rate of 5 feet per second when the ambient air temp is 78.3 degrees, can I still hear any difference between a 12 gauge 15 amp line and a 10 gauge 20 amp line, when playing side two of Zappa’s Burnt Weeney Sandwich LP?

Depends on if you’re sitting in the sweet spot or not, when the last time you cleaned your stylus was, and if you're listening to the Japanese pressing or not. 😎

Thankfully I can also have a sense of humor about this stuff.

Current doesn’t always go up when voltage goes down, it’s a little more complicated than that.

I agree with your statement, and my explanation of it probably wasn’t as specific as it could have been, but I didn’t want to get too crazy with theories, formulas and examples. Anyone is free to supply some if they wish.

Looking at the Crown Studio Reference 1 manual, I’ve never seen an amplifier with a damping factor of over 20,000! Wow!! That's a 30 amp plug alright. Thanks for bringing that to our attention.

@bigtwin 

Wow!! That's a 30 amp plug alright.   I'm confused by your comment. 

I've never seen an audio amplifier with a 30 amp plug on it before.