Circuit Breaker to Outlet AC Wiring and Ground

[Johnseye]

I'm bringing an electrician in to run dedicated AC wiring from my breaker box to outlets. My powered 2 channel equipment is different from surround except for the sub (when I listen to 2.1}.  I'm look for advice from those who have done this or are electricians.

 

The current plan is 2 dedicated 20 amp circuits with 10 gauge wiring including a wired ground going back to the breaker box. There will be a grounding strip in the box, but there isn't one now. I have a grounding bar in the ground outside which is connected by a 4 gauge cable to the ComEd electricity meter. That's how my house gets its ground. I have my own  well and septic so ground is not tied to any public water pipes or my well. One breaker will be for the surround equipment and the other for 2 channel. 

 

My biggest question at this point is whether I'll have a ground loop from the sub when it's being used by the surround system. The sub will be plugged in to the 2 channel circuit. 

 

Not sure if I'm missing anything. 

[bobfa]

 

 

I assume that all of the equipment is near each other and you will have two outlets. Make sure SURE that they are on the same Phase!  You still make make a ground loop.  There are several references on the internet on this stuff.

 

Here is one example :

 

http://www.goodwinshighend.com/room_design/electrical.htm

 

 

[Speedskater]

I would have the electrician run a heavy 120V feeder (say 40 to 60 Amp) to the music room. With a small 6 breaker box in/near the room.

That way everything can be connected to the same Safety Ground in that box.

 

Let the electrician worry about the connection to Planet Earth. It's called the GEC (Grounding Electrode Conductor). What you have now is probably all you need.

[WuNgUn]

40 or 60 amp may be overkill... But I'd run a feeder as well. I'd probably do 240V 30A (two 30A breakers) and use both "phases". When you run a sub box (2 breaker boxes) only the main box should be connected to ground, but the sub box is still bonded to ground. 

From a technical perspective, there is only ever one ground... And every thing else is bonded to it. 

I wouldn't connect your sub to both components at the same time. It's probably fine with just one running, but if you accidentally power up both, you'll be in for a surprise! 

 

[WuNgUn]

Also, if you're using isolated ground recepticles, you must run a dedicated, insulated ground conductor back to the panel box for each recepticle. 

However, I'm unsure if these conductors have to go back to the main box or not, which wouldn't very practical.... Likely fine to the sub box. 

[Ralf11]

one thought - be sure they use metal conduit, not plastic

[Speedskater]

I was writing about 40 to 60 Amps for a 120V circuit or 20 to 30 Amps for a 240V circuit.

 

One of the main reasons for the breaker box in the room is so that you only need one heavy Safety Ground/Protective Earth back to the main panel.

The shorter the S.G.s are from hi-fi component to component the better.

Nothing wrong with plastic conduit or real Romex® for that matter.

And if you use plastic conduit or  Romex®, you don't need Isolated Ground receptacles.

[Ralf11]

I'm thinking metal will help with any RFI, hence the conduit comment

[Johnseye]

Pipe conduit is code. No Romex for me. The two circuits will have their own ground back to the box. No safety ground. 

 

I don't see the need for a breakout box.  The main breaker isnt far from the room. 

[One and a half]

The one issue that may cause some worry is that with dedicated lines, the risk of the Ground to Neutral voltage starts to climb. With mostly reactive loads in audio circuits, the voltage will increase. If the neutral to ground is more than 2V at the main panel, it will be worse at the sub panel in the music room. There's a white paper attached for further reading on elevated neutral to grond voltages.

 

One way around this, is an isolation transformer in the music room, which has the output neutral tied to ground on the secondary. The problem then is find a home for such a beast. Advantages of the transformer are common mode noise is just about gone, plus surge suppression....there's a thread on it.

 

To think further on the loss of neutral for a split 240V system would severely damage any component, therefore not recommended. A single 120V feeder would be a better option, unless of course there's protection devices that detect loss of neutral and cut off the supply for the 240V feeder.

wp202.pdf

[Speedskater]

14 hours ago, Ralf11 said:

I'm thinking metal will help with any RFI, hence the conduit comment

True for both low frequency EMI and high frequency RFI.

But there are often other trade-offs.

Note that some jurisdictions require metal conduit.

[Ralf11]

yes, and his does

 

I wonder if any of the big high-end dealers there can recommend an electrician???

 

in a Metro area that large I'm sure others have done this and talked to dealers

 

or an audio club/society?

 

despite the well, you aren't really out in the sticks...

[One and a half]

It is possible to obtain EMP proof flexible metal conduit @ $250/foot. Most metal conduits aren't up to this quality, derating of cables apply. Metal conduit is mainly for protection against driving nails into electrical pathways.

[Speedskater]

The PowerVar "Neutral to Ground Voltage Causes and Cures"paper is not very helpful for residential power systems.

 

The frequently referenced Bill Whitlock, Jim Brown and Middle Atlantic papers are much better.

[Johnseye]

2 hours ago, Ralf11 said:

yes, and his does

 

I wonder if any of the big high-end dealers there can recommend an electrician???

 

in a Metro area that large I'm sure others have done this and talked to dealers

 

or an audio club/society?

 

despite the well, you aren't really out in the sticks...

 

I've asked and got a reference.  Most electricians I've spoken with claim to have experience in this area.  I've had 2 come by for quotes with one more coming this week.

 

I'm not going to spend $250/ft. on conduit.  I'd rather put the money elsewhere.  Good to know it exists though.

 

I was reading an article which stated the wiring should be "One with hot on one side of neutral.  The other on the other."  I don't know what this means exactly and it 2 electricians couldn't make sense of it.

 

Another recommendation was 4 wire cable with ground wire.  Why 4 wires plus ground?  How do the 4 wires get connected?

 

A couple other thoughts were: put power amps on their own circuit and separate heavy duty motors and compressors on a different phase from the audio equipment.

 

[Speedskater]

58 minutes ago, Johnseye said:

Another recommendation was 4 wire cable with ground wire.  Why 4 wires plus ground?  How do the 4 wires get connected?

Just like a Star-Quad microphone cable. But the NEC won't permit it for the size wires that we use in a home.

[Speedskater]

1 hour ago, Johnseye said:

A couple other thoughts were: put power amps on their own circuit and separate heavy duty motors and compressors on a different phase from the audio equipment.

Actually it would be a different leg or pole as US residential power is center tapped single phase.

Anyway, yes it's a good idea to put separate heavy duty motors and compressors on a different leg from the audio equipment.

But smaller power amps should be on the same circuit as the rest of the audio equipment.

[KingRex]

 I'm an electrician and have done a lot of experimenting on the best way to get power from my panel to my rack.  It's easy to create a ground Loop, but it's also very easy to avoid. Grounding is a very key element in the equation. An old ground rod attached to your panel may not drain as effectively as you want it to.  Utilizing dielectric potting material or a ufer ground in your foundation will greatly reduce unwanted noise.  

 

 There are also ways to approach this with materials such as cord that are not necessarily code legal but do a far better job than pipe or Romex.  Isolation from vibration of the Romex is also important.  Spacing from any other electrical circuits is also important.  

 

The type of box you put in the wall and the receptacles you install in that box are very important.

 

By far the best sound I got out of my system was a 10 gauge OFC cord from my panel directly into a distribution power strip. No receptacle in the wall, no cord from the wall to the distribution strip, just a direct feed into the distribution strip.  Cord can not pass through a floor, but hey, I want the best sound, and it can be done safely.   All my gear is fed from that one power strip. I have 2x135 watt monoblock amplifiers, a tube preamp, a DAC, a phono stage and computer server all fed from it. This was by far the most quiet and resolving installation I found.  Dynamics are very high and noise has been greatly reduced. Some of that noise being physical mechanical vibration you hear such as Toroids in your power amp humming.  

 

If you're going to go the all code legal route 2 x 10 gauge runs of romex will work fine.  Not all Romex is created equal. Cheap Home Depot Romex sourced from China run through high-speed dies is full of crystals and impurities. Slow drawn American-made copper is better.  It takes time and effort to find a distributor that carries that copper. It is available.  Very high Purity copper wire pulled through PVC and twisted during the pull is also an excellent installation.  $250 per foot is high, but your in NY.  I bill $640 per day.  You have maybe 2 days of work if you rebuild your panel and ground your system right.  

 

If you don't have Furutec receptacle, buy Albert Porter's, Porter ports.  Do not purchase isolated ground receptacles. They do nothing for you and actually have an inferior ground compared to a regular outlet.

 

Do not run 4 wire circuits. You do not want to share a neutral between the two circuits. Run two separate 3 wire runs.

 

Once again, ground ground ground. You want the best ground possible attached to your panel.  You want your new circuits grounds connected right onto that new ground bus in your panel. You want that ground bus connected directly to your new ground rod or ufer ground. You don't want it running through the case of your panel from the neutral bonding point to the Ground Bar.  If  the ground is landed on the neutral bonding point you want a 6 gauge jumper from there onto your Ground Bar.

[Speedskater]

1 hour ago, Johnseye said:

I was reading an article which stated the wiring should be "One with hot on one side of neutral.  The other on the other."  I don't know what this means exactly and it 2 electricians couldn't make sense of it.

Maybe it had something to do with that leg/pole thing. On leg is on one side of Neutral and  the other leg is on the other side.

So it's 240V from one Hot to the other.

On ther other hand it could mean something else.

[Speedskater]

4 minutes ago, KingRex said:

I'm an electrician and have done a lot of experimenting on the best way to get power from my panel to my rack.  It's easy to create a ground Loop, but it's also very easy to avoid. Grounding is a very key element in the equation. An old ground rod attached to your panel may not drain as effectively as you want it to.  Utilizing dielectric potting material or a ufer ground in your foundation will greatly reduce unwanted noise.  

While the Safety Ground connection to the Neutral is an important part of the AC power system, the connection to Planet Earth does not enter into the day-to-day operation equation. It's only there for safety during thunderstorms, high voltage failures and to keep the Neutral near the potential of the soil.

[Speedskater]

The only real Romex® is made by SouthWire. Everything else is Non-Metallic (NM) cable.

[KingRex]

45 minutes ago, Speedskater said:

Maybe it had something to do with that leg/pole thing. On leg is on one side of Neutral and  the other leg is on the other side.

So it's 240V from one Hot to the other.

On ther other hand it could mean something else.

What they are saying is use the same phase.  Always A or B phase.  There can be small differences in voltage between A and B phase.  That small voltage difference can cause voltage differential to ride on the ground casing humming.  

[KingRex]

40 minutes ago, Speedskater said:

While the Safety Ground connection to the Neutral is an important part of the AC power system, the connection to Planet Earth does not enter into the day-to-day operation equation. It's only there for safety during thunderstorms, high voltage failures and to keep the Neutral near the potential of the soil.

True but untrue.  It matters and will affect the SQ of your system.

[Ralf11]

2 hours ago, Johnseye said:

 

I'm not going to spend $250/ft. on conduit. 

 

 

 

I will bet that a stereo that can survive an electromagnetic pulse weapon is not high on your list.

 

power amps on their own circuit is good from the standpoint of power supply, but may create a ground loop...

 

how much does the Benchmark draw?

[fas42]

1 hour ago, KingRex said:

 I'm an electrician and have done a lot of experimenting on the best way to get power from my panel to my rack.  It's easy to create a ground Loop, but it's also very easy to avoid. Grounding is a very key element in the equation. An old ground rod attached to your panel may not drain as effectively as you want it to.  Utilizing dielectric potting material or a ufer ground in your foundation will greatly reduce unwanted noise. 

 

...

 

I like what you have described here - it's all about experimenting, and I've been down many paths, without actually doing something like what you have mentioned here. Once you know the quality you're after, it becomes straightforward to work out a configuration that gives something close to an ideal setup, for the equipment being used - purely via experimentation.