NMB with Isolated ground ?

[Speedskater]

On ground loops:

In systems with unbalanced interconnect cables (Audio, Video, Instrumentation or Control) ground loops are a fact of life. AC power leakage currents will use all possible paths to return to their source. So the best plan is to reduce the resistance (or impedance) of all these paths so that the leakage current voltage drop is reduced.
Reduce the length of the Safety Ground (EGC) wires from unit to unit. This is why those power conditioners that the hi-fi people like are sometimes effective, they connect all the Safety Ground plugs together.
Chose unbalanced interconnects with a heavy braided shield/return. For longer runs a shield equivalent to 14AWG is good.

When all else fails try this:

 

[ritelec]

Kevin..............Thanks for all that info :thumbsup:

By the way..........do you have any literature that tells you how to write a hit song?





Thanks again,
Rich

 

[kwired]

On ground loops:

In systems with unbalanced interconnect cables (Audio, Video, Instrumentation or Control) ground loops are a fact of life. AC power leakage currents will use all possible paths to return to their source. So the best plan is to reduce the resistance (or impedance) of all these paths so that the leakage current voltage drop is reduced.
Reduce the length of the Safety Ground (EGC) wires from unit to unit. This is why those power conditioners that the hi-fi people like are sometimes effective, they connect all the Safety Ground plugs together.
Chose unbalanced interconnects with a heavy braided shield/return. For longer runs a shield equivalent to 14AWG is good.

When all else fails try this:

View attachment 6521

Like I said that is a problem related to amplifier output more so than premesis wiring.

Plugging the two devices shown in the picture to the same receptacle - even if isolated ground type supplied by NM cable should electrically be the same as not having a isolated ground receptacle. The added bonding wire is not part of premesis wiring and solves no premesis wiring problems - it solves problems related to amplifier output.

If you have objectionable current flowing on equipment ground that is a premesis wiring problem - likely neutral - ground bond where it does not belong. The jumper could mask that problem but does not make it go away.

 

[ritelec]

Assuming premises wiring is correct.....why the noise, hums, clicks, and buzzes when dimmers are turned on or washers or other motor loads are turned on.......


So we have correct premises wiring, and no shorts to ground in the audio equipment..............why the noise?


I'm agog.

 

[K8MHZ]

Assuming premises wiring is correct.....why the noise, hums, clicks, and buzzes when dimmers are turned on or washers or other motor loads are turned on.......


So we have correct premises wiring, and no shorts to ground in the audio equipment..............why the noise?


I'm agog.

It's because your home's electrical system was not designed to operate noise free. Most homes are wired according to the NEC which is a publication based upon the safety of personnel and the premises, and is a bare minimum at that.

That system is supplying power to appliances not designed to be electrically quiet. Sensitive electronic equipment will pick up that noise unless mitigated in some manner.

At least you have control over the cause of the interference that plagues you. I am an amateur radio operator and have had to deal with interference sources not on my property. Just tracking them down can be a daunting task, getting a repair done may be next to impossible, since I don't own the offending device. Then, I do have the option of trying to get the FCC involved, which is no fun, and is like calling the federal cops on my neighbor.

Edit to add: The noise may not be traveling through your wiring. Get a cheap AM radio and tune it to a point where there is just static and as little of that as possible. Operate the devices that cause interference to your audio system while listening to the radio. If you hear the same noise, it's RF interference and may not have anything at all to do with the way things are wired, or just the opposite, the house wiring may be acting as an antenna. By moving the radio around the house, you should be able to tell the difference. If the wiring is not involved, the signal will weaken as you get farther from the device. If the wiring is involved the signal strength will be varied as you move around and not related to the distance between you and the device.

 

[Speedskater]

Like I wrote in post #39:
This thread seems to be going about a dozen different directions!

Like I said that is a problem related to amplifier output more so than premises wiring.

Actually it's related to power supply AC primary current leakage in each piece of equipment.

Plugging the two devices shown in the picture to the same receptacle - even if isolated ground type supplied by NM cable should electrically be the same as not having a isolated ground receptacle. The added bonding wire is not part of premesis wiring and solves no premesis wiring problems - it solves problems related to amplifier output.

Yes, the picture is about connecting several units together.
No, the picture is not about a premises wiring problem.
Most NM cable systems don't need an isolated ground.

If you have objectionable current flowing on equipment ground that is a premesis wiring problem - likely neutral - ground bond where it does not belong. The jumper could mask that problem but does not make it go away.

True, the picture can't correct premises wiring problems.

 

[ritelec]

Thanks Ray Jay.......or was that Mr. Johnson (K8MHZ).

Kevin...........where is that ground from the chassis going? Tell me it's stuck into the receptacle ground..........or is it going to a made electrode around the building?


Come here my little Furman balanced power conditioner..............he plays so nice nice.

 

[Speedskater]

The picture is from a paper on test equipment system grounding. It's by Audio Precision who manufacture very high end (and high price) audio test equipment.

http://ap.com/kb/show/151

They publish a "Notes from the test bench" paper like this almost every month.

 

[Speedskater]

Under the picture of two AP switchers, is the text:

Fasten the one end of the lug to the switcher with a large, truss head screw. Attach the other end to one of the ground posts on the front of the analyzer.

 

[Dennis Hamilton]

It's not an issue. It's just that hifi/audiophile home owners can be whacky with some of their electrical designs. It can be a place where engineering and folklore combine. Isolated grounds even when you are using non-metalic boxes is only the start.

Best things to do with these guys is to make sure the run NMB run to the hifi equipment is a home run to the panel with no other outlets downstream, or run a new one if you have to, than put in an Orange receptacle, and tell them they have an isolated ground. They would never know the difference.

 

[Dennis Hamilton]

This thread seems to be going about a dozen different directions!

For everything you need to know about AC power wiring to Audio/Video systems and for that matter instrument or control systems, the following papers total about 145 pages of good information.

The Bill Whitlock of Jensen Transformers Seminar paper
http://www.jensen-transformers.com/an/generic seminar.pdf

The Jim Brown of Audio Systems Group white paper
"Power and Grounding for Audio and Audio/Video Systems"
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf

"Power White Paper" from Middle Atlantic.com
http://www.middleatlantic.com/power.htm

or a different version of the same paper

"The TRUTH" from ExactPower of Middle Atlantic Products
http://www.exactpower.com/elite/wpapers.aspx


If that's not enough reading, try:

http://www.hottconsultants.com/
http://www.audiosystemsgroup.com/publish.htm
http://www.jensen-transformers.com/index.html

Some really great links... Thanks for putting them up.