20 years in construction taught me to wire up switches, duplexes, even live strings of lighting, but where I live, electrical work is done by pro's and inspected. I watched close when my standby generator was installed (why I don't use UPS) and didn't see any deviation from how I'd have done it, but I don't do any wiring here beyond replacing outdoor light fixtures.
 
Lets me sleep at night.
 
I told the bidders I wanted two 20 amp home runs for good power for audio equipment (and an outdoor circuit)  and got comparable prices with standard residential installs. I suspect bids would have been much higher if I'd uttered the words "recording studio". I picked from the middle of the pack, largely because they also service my generator.
 
The new audio power circuits are quiet as a mouse, tho I do have problems where equipment in split between new and old, but that may go away when I re-route those supplies.
 
The biggest question I had has been answered, here and in practice, I wanted to know how the two new circuits were likely to interact, ground and noise wise, and I have the impression the work was done as suggested here, because the system that now splits the two new outlets is quiet to max gain, and the only remaining issues are equipment on the old circuits.
 
I greatly appreciate the expertise offered here, and hope this will come up in searches for other people who might benefit down the road.
 
Thanks guys!

so this may be going a bit far afield for a forum post, apologies if that's the case!

There are two ways to address electrical noise problems in a studio setting - you can deal with it at the source, or at the destination<G>. Noise is a given, and it is only going to get worse!

Noise is not, however, the problem... noise entering audio circuits is the problem!

I would never EVER suggest that you should not start with the quietest possible power system... that's just plain common sense. Less noise means it is easier to suppress it!

BUT, not everyone can start with a clean power and grounding system, so it is important to understand how noise gets in. And how you can mitigate it.

The first problem is single-ended interfaces. I don't want to sound like a snob, but single-ended inputs are a huge problem waiting to happen. Single-ended outputs pose less of a problem, but ANY TIME you share one conductor for signal return and shield you are starting out at a disadvantage.

Sadly, many manufacturers have forgotten the lessons of the past, and connect the shield in a balanced input to the circuit board. This is referred to as the "Pin-1 Problem", and it has been covered in great detail since 1995. If you search for "Pin-1 Problem", and Bill Whitlock or Neil Muncy or Jim Brown you'll find lots of material. The short version is that the shield should always be connected to the enclosure, and never to the circuit board.

Back in the 1990s I rebuilt an old analog console. One of the things I did was install a large copper buss bar, and I connected ALL the shields to that buss bar. At the time I assumed that the buss bar was responsible for the remarkable improvement in S/N ratio. Now I'm not so sure, I think it probably had more to do with removing the shields from the motherboard. One of these days I will test this hypothesis and report back.

What all of this points out is that a balanced interface is ideal, and that proper interconnection between a balanced source and a balanced input, including keeping the shield outside of the enclosures, and using cable with a braided or  Reussen shield instead of a foil shield, and no drain wire, and a tight, uniform twist. All of these things matter.

If you don't have balanced outputs then you can get the same noise suppression by wiring the connection as it it were balanced. There are lots of how-to documents, I recommend Rane App Note #110. Bill Whitlock has also written about how a single-ended source need not degrade performance of a differential input.

If you are dealing with single-ended inputs there is little you can do, other than balancing them. You can use transformers (use an input transformer, there is a difference) or you can build a transformerles input, the easiest way is to use the THAT InGenius(tm) chips. It isn't as expensive as it sounds if you only have a couple of inputs.

And putting to rest a myth that just won't go away... cable shields do next to nothing for typical noise problems. Twisted pairs and differential inputs do most of the heavy lifting. Shielding is only effective at radio frequencies, at power line frequencies the twist is the magic.

Speaking of which, if you are installing new power circuits consider using twisted wire from panel to outlet. It is available, it isn't horribly expensive, and it meets code. There is even a version that is shielded, and if you do have a lot of RF hash on your power lines it is quite effective.

That's probably enough general stuff for now... feel free to ask questions!

In the meantime for Jay Tee - for your equipment that is on the old power circuits...

Can you confirm that this gear is the only gear that is acting up, and if so does it act up when connected to gear on the new power, or stand-alone, or both? There are a number of potentially (pun unavoidable) inexpensive solutions that might help.
 

A few points:
 
Not saying it wasn't done in the past, but, kitchen and bathroom circuits are not supposed to supply any other rooms besides those rooms...period. Code requirement now says "thou shalt not". Kitchen circuits, however, are permitted to supply dining room outlets.
 
A circuit breaker is not designed to save your life from electrocution. It is sized and designed to protect the wire insulation and prevent the wire from overheating and melting or damaging the insulation on it, thereby causing a fire from an overloaded condition.  A 20a circuit breaker (CB) will trip very close to, and generally slightly above the 20amp load level but that depends too on the duration of the load being applied. Commercial circuits are designed to run either continuous or intermittent. A continuous load should not exceed 80% of the branch circuit rating by code. Example of a continuous load being a lighting circuit in a store that will run for more then 3 hrs continuously. For a 20A CB that equates to a maximum full continuous load of 16a drawn from the circuit.
 
GFCI protection (ground fault circuit interrupter) is actually designed to prevent electrocution under CERTAIN circumstances, but not all. When the GFCI senses 7ma of current "leaking" from the circuit back through ground, it is designed to trip. If no current is leaking it will trip like any other CB at it's normal factory current rating.  There is no safety advantage to using them in any other places so, use them only where the code requires which is generally where they are close to water (kitchens and bathrooms) and outdoors and in basements and garages. The reason they are not "safer" in other "dry" locations is that often there is no path to ground for that "leaking" current to allow them to work properly.  The current in those cases, is not "leaking" from the circuit... it might be completing the circuit through your chest, going from the hot wire back to the neutral, but if it's not leaking out to ground, the GFCI is not going to trip. The GFCI sees that current flow as normal since it's not leaving the circuit and so it does not trip.
 
AFCI protection (arc fault circuit interrupter) is designed to "see" the signature of an electrical arc and shut down the circuit. Code now requires these in the USA in circuits feeding outlets and devices in sleeping areas. I'm not sure, but they may also be required now in other areas of dwellings as well. I don't actively work in the electrical construction side of things so I don't keep totally up to date on code changes that don't affect my day to day operations.
 
The amount or level of current that will kill a human varies from person to person and depends on many external factors such as health, level of voltage present, and probably most important, the conductivity of the skin which also varies throughout the day and with our activities.
 
We can generally feel 1ma under the right conditions as a tingle. 10ma gets into the area of pain and muscle contractions.  Somewhere along that upward level, the contractions are strong enough that the person is unable to "let go" of the energized object on their own. Depending on health of the person, 30ma to 60ma is the threshold for fibrillation.  Sustained contact results in tissue damage from the current, which produces heat in the tissue. Just like a shorted wire heats up, the tissue heats up and damage occurs at relatively low temperatures.
 
Ohms law applies.
 
Anyway..... thought you might like to know.  class dismissed

Good stuff wst3. 
What popped into my head while you were explaining the pin 1 issue , is how many folks have issues with usb buss powered audio interfaces. Personally I don't recommend using buss power for audio interfaces. 
I owned a buss powered Fast Track pro that I gave up on because of a hi pitched noise. Later reading many posts by others with this issue I realized that this was a common issue with all buss powered interfaces. A special USB cable will solve the problem,, but to me that's not acceptable. 
 
My studio was wired by a guy who wires hospitals and even though we opted out on the orange outlets ( $$$) he used  isolated grounding. 
 
The main reason my friend advised keeping motor loads off your studio circuits was more for load draws that happen when they kick in. I have a friend who's lights go dim for a second every time his pump cuts in. Of course this all goes back to how a home was wired. People tend to go with the minimum. My gang likes to overbuild. Where the code allows for the 12 outlets, we use 8 to 10. My friend with the pump issue used #12 wire and the run is 200'. He will be replacing his burned out pump as a result. My pump has #10 wire @ 150' My lights don't go dim. 
 
Which brings us back to wire size/ breaker size. This is for Canada /USA. 
I'm just quoting from what I understand and not from a professional view so bash me if wrong. 
In a workshop we need heavy duty outlets for power tools and motor loads. 
In a house, all appliances will never exceed the need for a standard 15 amp breaker. 
Therefore household circuits are standardized to handle the potential requirements of each room. It is also standard practice to balance the rooms with the circuit sharing lighting and outlets. Last time I looked this was 12 per circuit. It seems to change. 
#14 wire is also standard as that matches the current requirements of 110v/ 15 Amps. 
If you were to use #12 wire this would absorb more heat from an overload and the breaker might not trip as expected. 
So as far as I understand you match the wire to the breaker. 
#14 = 15 amp 110V
#12=  20 Amp 110V 
Sizes beyond that are then usually 220V . Reason being of course is as the voltage this doubles the available watts without requiring larger wire or breakers. 
Example, most electric baseboard circuits are#12 wire and 20Amp breakers. 
 
Anyhow ,around here nobody will have 20 Amp Household circuits in living rooms and bedrooms. They would be considered dangerous. 
 

not being a registered electrician, I think I miss stated my previous about one recepticle on a 20 amp circuit.  I was trying to say I THINK on 20 amp recepticle (the round ones, that look like a regular two slotted w/ground) per circuit.  Always open to be told wrong.

Cactus Music
 #12 wire and the run is 200'. He will be replacing his burned out pump as a result. My pump has #10 wire @ 150' My lights don't go dim. 
 
Which brings us back to wire size/ breaker size. This is for Canada /USA. 
 Last time I looked this was 12 per circuit. It seems to change. 
#14 wire is also standard as that matches the current requirements of 110v/ 15 Amps. 
If you were to use #12 wire this would absorb more heat from an overload and the breaker might not trip as expected. 
 
Anyhow ,around here nobody will have 20 Amp Household circuits in living rooms and bedrooms. They would be considered dangerous. 
 

 
Wire length with a fixed resistance per foot, times the current of the load, equals a voltage drop across the wire distance. If the voltage at the load is too low, the device will not function, and may burn up due to overheating as it tries to run on a lower voltage. This will burn up a pump. A larger wire will display a lower resistance per foot, allowing the voltage to be higher at the load. I deal with this all the time when installing fire alarm signaling circuits and the horn strobes we place on those circuits.  the larger the gauge of wire, the less voltage drop across the wire. Bigger is better, but bigger costs more, so many folks will use the smaller size wire on circuits when cost is a factor, like in house living room and bedroom circuits. Loads tend to be smaller so it's often not a big problem.
 
Using ohms law E over IR  and power ohms law P over IE, you can calculate the voltage drop and the power dissipated as heat in the wire. Resistance per foot is obtained from the NEC tables and appendix or google it.
 
I believe it is a common calculation to use 180va for an outlet in factoring the maximum number permitted on a circuit based on CB size. So 12 on a 20a CB would seem about right as the max number. Less is OK too. I try to limit them to 7 or 8 depending on the circumstances when I am wiring something new.
 
#14 ga cu wire is correct for a 15a CB.  Using a #12 cu wire would be OK too. The larger wire does not "absorb" more heat. The CB will still trip at the correct level of overcurrent. The CB's trip based on 2 things.... one is heat build up over time in the circuit breaker (not the wire) .... this is the reason a circuit for continuous duty (3 hrs or more non-stop) is derated to 80% or 16 amps on a 20amp CB. The other reason it trips is due to the magnetic field created by the current. Some CB's are designed to be used in motor applications and will hold 2 to 3 times their rated current for a very limited time. These breakers have a special marking to indicate this. Usually about one and a half seconds is all they will hold depending too on the level of the current. This is to allow a motor or a compressor to start properly. I have metered 50+amps on a 20a CB on motor start and the CB holds..... but not for long. In a locked rotor condition....click after 2 seconds or less.
 
A 20 amp circuit is no more dangerous than a 15 amp circuit. Size the wire and breakers correctly and they are both just as safe. I would prefer to have 20a circuits over 15a circuits because they can hold a larger load.
 
In my old house, some of the wiring is certainly not up to today's code requirements. It's not dangerous, just that the bathroom circuit also feeds other rooms. So a few times, my wife would be using the blow dryer and the hot curlers and the TV was going and a few other things like some lights, when suddenly, the 15a circuit breaker tripped.

mixmkr
not being a registered electrician, I think I miss stated my previous about one recepticle on a 20 amp circuit.  I was trying to say I THINK on 20 amp recepticle (the round ones, that look like a regular two slotted w/ground) per circuit.  Always open to be told wrong.

It's imprinted in the outlet device's plastic so it can be identified in the field. Plus, the neutral slot looks like  "T" rather than a straight slot.

"Using ohms law E over IR  and power ohms law P over IE, you can calculate the voltage drop and the power dissipated as heat in the wire. Resistance per foot is obtained from the NEC tables and appendix or google it."
 
2KIL/CMA is the voltage drop formula. K= constant which is 12.9 for copper, I = amps of the required load, L= distance to the load in feet. Circular Mill Area ( CMA ) can be found in the chapter 9 of the NEC.
 

"A 20 amp circuit is no more dangerous than a 15 amp circuit. Size the wire and breakers correctly and they are both just as safe. I would prefer to have 20a circuits over 15a circuits because they can hold a larger load"
 
Absolutely... You won't find 15 amp branch circuits in commercial buildings. You would be pretty hard pressed to get a breaker to trip using your body as the load. GFI and ARC fault protection are much better at this.
 
It seems this thread has split into two separate topics: power quality and electrical safety.
 
Rocky

bluzdog
It seems this thread has split into two separate topics: power quality and electrical safety.

They aren't really separate topics, but it is wise to place safety first! It is really pretty easy to build a safe, and quiet technical power system.

Bill, I can't confirm specifics right now, but I will when I can. What I know at this point is three areas of noise, spread over four rooms of equipment. Guitar and bass I'm not worrying about at this point, if ever, leaving twoIissues.
 
In the control room, interfaces, pres and processers are on the new circuit, while both PCs are on house wiring. I get hum when both interface outputs are into the small mixer. Either by itself, no prob. First move there is to get the PCs onto the new circuit and see whats what. Theres a nest of surge protectors involved, which allow the WAN demarc, firewall, and switch to remain up fulltime, ISP requirement, and another switch that goes up and down w the PCs, pkus a third layer to allow me to power off the  video monitors while the PCs stay up. Ima have to move that carefully to preserve that functionality, hence the delay.
 
The other issue is in the listening room, where feeds from a laptop DAW for remote recording, come together w feeds from the tracking room, thru a mixer into flown stage monitors above a large LCD. TR is on a new circuit, laptop and monitors are on house wiring. 
 
Tougher to get them off the house circuit but may not have to. Part of the current upgrade is to connect tracking, control, listening/laptop, and an iso room together. Backbone is ADAT via lightpipe thru an Optiplex +. There's an excellent chance the noise issue will disappear when the balanced audio runs are replaced w fiber, since selective unplugging negates it now.
 
More as I have it, and thanks! Much help!