[rcag_ils]

We are going to build a new house. I specifically asked the builder to run one run of AC in every room that won't have appliance plugged into it.

Is that good enough, or I still missing something?

[ctviggen]

That's code, so naturally it will happen.  What is your goal?  You might have them run separate circuits to where you plan on having your equipment.  Other than this, I don't know what else you can do.

[gjs_cds]

I had our guy run a dedicated circuit to my main listening room.  The cost was minimal, and it's a good peace of mind.  There are also ways to try and get (decent) surge protection per-circuit as well.  (Although, if the lightning wants your gear, lightning gets your gear.)

[oneinthepipe]

I suggest two or three 20A dedicated circuits in your listening room.  This way, you will have separate circuits for your preamp and for your amp.  Then, you can plug any potentially noisy stuff, like a computer, into a completely different circuit, since you will also have another (third or fourth) circuit in the room.  The cost should be minimal.  You can also consider isolated ground circuits, although there is some debate about their effectiveness. 

Also, you might ask the electrician to install the "audio" circuits at the top of the panel and "noisy" air conditioner and kitchen appliance circuits in the bottom of the panel.  I don't know if this has any effect, but I read the suggestion somewhere else, and there is an opinion that circuits at the top of the panel are less noisy.  Regardless, it doesn't cost any more.  Also, I read that these dedicated circuits should be wired back to the main panel rather than to a sub-panel to minimize noise.  You can also use arc-fault breakers to protect equipment, although your local code might require this already.

With the new house, are you building a dedicated listening and/or HT room?     There is a lot of good info on the Acoustics Circle about room construction, and not just major stuff, like vibration resistant floors and walls, but also about room shape, doors, etc.

Anyway, congratulations on the new house.   

[rcag_ils]

That's code, so naturally it will happen.

I am not sure if it's code in a sense that they will have to install an "audio outlet" for you.

I have an that amp has hum in one AC outlet and not the others. I have vintage AM radio that pick up noise from my range stove when it cycles on/off.

I may just have them to install a dedicated AC run for appliance, then the rest of the power will be clean.

Also, you might ask the electrician to install the "audio" circuits at the top of the panel and "noisy" air conditioner and kitchen appliance circuits in the bottom of the panel.

I wonder if they will do two separate power panels, one for audio, one for appliance.

With the new house, are you building a dedicated listening and/or HT room?

No dedicated custom designed listening room.

But there will be separate rooms for everything. Like a room dedicated for kids playing. One big room upstair for entertainment. One living room downstair with fireplace. Two big bedrooms in case we decided to use them for something else other than bed room. These rooms I can try to have them to put isolation in the inside wall to cut down the noise, and put some acoustic wall stuff (don't know what) to improve the acoustic.

But no, I don't plan on having some guys over to run pink/white noise test.

[oneinthepipe]

Like a room dedicated for kids playing.

We have a "dedicated" playroom for the kids, but they aren't necessarily "dedicated" to playing there. 

[ctviggen]

I suggest two or three 20A dedicated circuits in your listening room.  This way, you will have separate circuits for your preamp and for your amp.  Then, you can plug any potentially noisy stuff, like a computer, into a completely different circuit, since you will also have another (third or fourth) circuit in the room.  The cost should be minimal.  You can also consider isolated ground circuits, although there is some debate about their effectiveness. 

Personally, I'm installing an isolated ground circuit (actually, two) using hospital-grade isolated ground outlets, which I may have cryogenically treated.  But I'm also running EMT from the panel to a metal box into which the two outlets will go.  This should provide effective shielding.  I think some question whether houses generate enough RF to require isolated ground circuits.  I figure it's not that expensive to do while the walls are open, so I might as well do it. 

[Wayner]

The first step in this process is to understand and identify the "usual suspect" appliances. These tend to be devices that have motors, or control relays. That makes a list of several appliances already and in no particular order are furnaces, washing machines, water softeners, refrigerators, freezers, stoves/ovens, garage door openers and air conditioning units.

Now the home has two 120 volt and 1 neutral lines that comes into the panel box, and there is a ground rod that goes directly from the box to earth ground. Obviously, we can't put all of the potential "noise makers" on just one side of the box. The electricians job is to balance the load. However, there may be some benefit to using the house wiring to try and distance a dedicated audio 120 volt line.

The obvious appliances that will come on at any random time are the refrigerator, freezer, air conditioner and furnace. The furnace is the real enemy. It has a nasty motor (if it's forced air) that will put a spike into the line. I would have the electrician make sure the dedicated outlets are on the other 120 volt leg from the furnace. Now, for the thought that the further down the box you go, the quieter it gets, perhaps is a bit optimistic. One side of the breaker snaps onto the power rail and the other gets connected to the neutral, which is shared by every outlet in the house, regardless of which side of the box they are on.

Some of this noise fear also comes from past bad experiences. However, strides have been made to make modern day appliances more noise free. AVA for example uses toroidal transformers which are a natural noise filter by design. That is the reason many device manufacturers turn to them rather then the old fashioned core and coil transformers of years gone by.

I do have a dedicated service to my main room, but the electrician put it on the same side as the furnace. I never hear the on/off spike from the motor. My studio has 2 dedicated circuits that are on each side of the breaker box. That has all ov the usual noise makers all scattered about too. There are no hints of any noise of any kind. I do have a dedicated "Monster" power box in the main room, but have no filtering in the studio, which is strictly vinyl in near field.

The only suggestions that I can make is (unlike me) keep the circuit for the furnace on the other side of the breaker box. And unless you plan on having 2 or more 550 amps in bi-amp mode, a 15 amp circuit is probably enough. If you want 2, go for it.

Isolated grounding receptacles depend on local codes. Some residential codes require conduit, some are fine with romex. All the isolated ground does is remove the ground strap on the outlet from grounding to a metallic box (as in hospitals) to prevent sparks in rooms that may have oxygen tanks which may cause a fire (burnt up patient, no good).

The better ounce of prevention in my book is to buy/install name brand appliances, make sure all wire to terminal connections are tight and if you are going to have low voltage lighting or dimming, keep those wires at 90 degrees to your dedicated wires to prevent noise.

Good luck to you and congrats on the new house.

Wayner 

[ctviggen]

Isolated grounding receptacles depend on local codes. Some residential codes require conduit, some are fine with romex. All the isolated ground does is remove the ground strap on the outlet from grounding to a metallic box (as in hospitals) to prevent sparks in rooms that may have oxygen tanks which may cause a fire (burnt up patient, no good).

This is not why a lot of people use isolated outlets and grounds.  Tons of non-hospitals use isolated grounds.  The facility I worked in two months ago (no longer there) had them everywhere.  The isolated ground creates a faraday shield around the conductors inside the metal channel, because the metal channel is grounded.  The body of the outlet is grounded to the metal channel/metal box.  There's still a "ground", a hot, and a neutral on the outlet. 

Thus, theoretically, you should have less RFI affecting the isolated ground.  The question is, how much RFI do you have in a typical house and is the isolated ground worth it to correct that amount of RFI?  I don't know the answer to that, but I'm going to install the isolated grounds anyway.  Also, these don't prevent trash that's already on the power from getting to the devices connected to the outlets.

[Wayner]

I didn't say there wasn't a ground. The strap that mounts the outlet to the (metal box) is not in the grounding scheme. The outlet was designed for hospitals initially. I don't know where the RFI notion comes from.

Wayner

[oneinthepipe]

Don't forget a couple of dozen of these: 

http://alanmaherdesigns.com/InfinityCBF.aspx

 

[Listens2tubes]

Don't forget a couple of dozen of these: 

http://alanmaherdesigns.com/InfinityCBF.aspx

 

Made with special sauce, just like the Whopper! 

[oneinthepipe]

Don't forget a couple of dozen of these: 

http://alanmaherdesigns.com/InfinityCBF.aspx

 

Made with special sauce, just like the Whopper! 

The Big Mac, too (although a Frozen Coke and Whooper Jr. is one of my favorite meals).

The special sauce name comes from McDonald's 1975 advertising campaign featuring a list of the Big Mac's ingredients: "Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun."    Wikipedia     

[rockadanny]

Wayner - thanks for the detailed explanation. 

[ctviggen]

I didn't say there wasn't a ground. The strap that mounts the outlet to the (metal box) is not in the grounding scheme. The outlet was designed for hospitals initially. I don't know where the RFI notion comes from.

Wayner

Here's a primer:

http://www.ruelsa.com/notas/tierras/pe30ig.html

"Clearly the conduits and raceways provide EMI/RFI shielding of the power and IG conductors contained within them. A more practical benefit, though IG wiring minimizes stray ground currents (see Figure 10)."

[rcag_ils]

When I installed equipment for work, we grounded the AC box to the earth ground, we grounded all the cable ladders and trays as well, I am not sure if they do it in residential wiring.

[ctviggen]

I'm not entirely sure what you mean, but if you use a raceway or the like, you would ground that also in house wiring.  For instance, I put a metal raceway in the garage and the raceway is also grounded. 

That's a little different, though, because the outlet's frame is connected to the metal box, which is connected to the raceway, which is connected to a ground wire at the beginning of the raceway.  In an isolated ground system, the outlet's frame is isolated from its ground wire.  The metal box and metal tubing are grounded back at the electrical panel (although some run an extra ground wire for the metal box) and there's no connection between the ground of the outlet and the ground of the metal tubing/box, except at one point -- the electrical panel.  Theoretically the grounding of the metal tubing/box terminates only at the electrical panel and is a "one way" ground.  That's why it rejects RFI, because the entire metal system should be grounded.  This is why it's used where sensitive equipment is used.

A separate issue is whether this really does any good in residential wiring, as how many sources of RFI will there be?

[Wayner]

Conduit for home wiring is not a universal code. That varies from town to town or state to state. Where I am at, romex wire is just fine.

Wayner

[FredT300B]

The most cost-effective wiring upgrade is one 20 amp dedicated circuit to your equipment. A 20 amp circuit is usually wired with 12ga romex (versus 14 ga for a 15 amp), but the receptacles will accommodate up to 10 ga, so that's the preferred choice. Anything beyond one dedicated circuit and receptacle is fine, but the one circuit accomplishes the main objectives of adequate current delivery and isolation from noisy appliances on other circuits.

[Anji12305]

If it doesn't cost more, a dedicated line for one room makes some sense.

It may not be entirely necessary - there are OneAC isolation transformers regularly available at auction as remediation.
The proviso - a large transformer can generate noise from vibration.

I think the idea of having a simple surge supressor may be sufficient (and cheaper).
There may be some sense to building in some protection, while roughing in the room.
http://www.panamax.com/Products/In-Wall/Default.aspx

I use an older, rackmount version of the product for my front end and it quietly protects me from power surges.