Grounding Metal Outlet Boxes and Isolated Ground Receptacles

First, I assume cdrc’s comments are directed at stickman451.

Second I believe the electrician stickman451 hired is a licensed electrician. I determined that to be the case by the posts of the OP when describing the wiring methods and materials used for the installation. From this side of the monitor reading the OP’s posts I do not know the quality of workmanship of the install. I assume it is fine.

cdrc said:

I don’t know if it is a bad idea but I do not think it is good. I also would doubt what you outlined is within code not knowing which state you live in.

The wiring method and materials used in stickman451 posts, for the installation, meets NEC.

What amperage breakers are you using?

I believe stickman said the branch circuit breakers are 20 amp. NEC code, for a NEMA 20 amp rated receptacle says a 20 amp branch circuit breaker must be used. Minimum size branch circuit wire used is #12awg. NEC code is bare minimum. NEC code is not intended to be used as a design manual.

I would DEFINATELY run a separate wire to bond your metal boxes and emt raceway.

At the time of his posting of this thread he has a box ground. He actually at the time of his posting had 2 equipment ground wires at each metal outlet box. One for the box ground and the other for, what stickman451 thought at the time, the IG (Isolated Ground) terminal of his duplex receptacles. Go back and read my responses to him on the subject.

For your Furutech receptacle ground wires I would braid them as you see in my sub panel pic. This will firthur reduce your noise floor a great amount from this simple trick.

That is not a braid. The green equipment grounding conductors are twisted together in a spiral. They are not braided, weaved together with one another.

To braid, simply install one end of your ground wires in a drill chuck, tighten the chuck and run the drill. Get a nice tight braid, the difference will be magical.

You might get that pass an electrical inspector beings they are equipment grounding conductors, but I would be willing to bet he would red flag the job if you used that method twisting the HOT and Neutral conductors together that way.

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Here are a few things I found looking at your pictures where I believe you could improve the SQ, sound quality, of your audio system.

* Get rid of the steel ferrous EMT conduit and steel boxes.

* For exposed work use MC cable with an outer aluminum armor instead, if possible. Solid core wire only! Stranded wire will smear the sound. Boxes could be malleable aluminum boxes.

(In your case, from looking at your pictures, you could have built a box out below the surface mount electrical panel. The box out could have a removable cover if you thought you needed access for future installs or changes. With this method you could of used NM-B sheathed cable, (Romex is a Trade Name). Plastic boxes, for your branch circuit outlets receptacles. Providing NM cable is approved by the AHJ in your area.) The installation would meet NEC.

* Avoid STEEL ferrous receptacle cover plates! Even low grade stainless steel cover plates will have ferrous impurities in the stainless steel. Use a strong magnet to check for ferrous materials. A steel receptacle cover plate kills the SQ of an audio system. See my post above on the subject. By the way the late Al Sekela was an EE.

In your case you could pull the raised 1900 duplex receptacle cover plates and replace them with a 1900 raised device cover plate. Fasten the cover to the 1900 box. Support the back strap of the duplex receptacle to the device cover. Install a P&S non-breakable nylon cover on the duplex receptacle.

Example of:

http://www.homedepot.com/p/4-in-Square-Single-Device-Mud-Ring-Raised-1-2-in-50-Pack-8772/202056884

] http://www.homedepot.com/p/4-in-Square-Box-Cover-2-Devices-Case-of-25-52C17-25R/202595756 [

* Technically a true dedicated branch circuit never shares the same conduit with other branch circuits. Not only can a voltage be induced from the current carrying hot and neutral conductors to other circuits sharing the same conduit but also the AC noise of the current carrying conductors.

* At least for audio equipment if conduit is used, twist the hot and neutral conductors together in a slightly to moderate spiral twist the entire length of the branch circuit wiring. Just install the equipment grounding conductor straight along side the hot and neutral twisted pair.

* For 120V audio equipment that is connected together by wire interconnects all audio equipment should be fed from the same Line, leg, in the electrical panel. ALL from L1 or all from L2. NOT from both.

Jim

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EDIT:

* For 120V audio equipment that is connected together by wire interconnects all audio equipment should be fed from the same Line, leg, in the electrical panel. ALL from L1 or all from L2. NOT from both.

This may not be practical, electrically a good practice, in all cases. Especially where big 120V fed mono amps are used in an audio system. A good example might be a pair of Krell 600 mono amps.

Putting both power hungry mono amps on the same Hot Line, leg, to neutral without trying to balance the load across the two Lines, legs, in the main electrical service panel could stress the electrical service panel bus and main breaker as well placing a large unbalanced load on the service neutral conductor and the power company’s utility power transformer.

It would be less of an issue if the electrical service is 200 amp or even less an issue if 400 amp. If the electrical service is 100 amp then the unbalanced 120V load could/would be a problem. If the house is old and the service might still be a 60 amp that would definitely put a strain on the electrical service.

Technically when fairly large 120V loads are know they should be balanced across the two Lines, legs, in the electrical panel. Only the imbalanced 120V load returns on the service neutral conductor to the utility power transformer. Example: IF all the 120V loads on L1, leg, equal 40 amps, and all the 120V loads on L2, leg, equal 40 amps then zero amps will return on the service neutral to the source. In this case the power company’s utility power transformer. In the case of a sub panel the same thing holds true. Only the imbalanced load returns on the feeder neutral to the main service electrical service neutral conductor.

The balanced 120V loads on L1 and L2 are in series with one another.

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