Grounding Metal Outlet Boxes and Isolated Ground Receptacles

LOL, believe it or not tests have been done using non breakable nylon duplex cover plates. I for one tried the nylon plate after Albert Porter posted he was using the P&S plates. Of course Albert’s post was back around 2005. I think the important thing about the P&S nylon plate, and the Leviton plate as well, is the backside construction bracing. Also the nylon plate does not ring like a plain hard plastic plate does. The nylon plate basically is just covering the wall duplex outlet while adding some dampening.

Stay away from any duplex cover that has ferrous materials in it. Steel is the worst. Low grade stainless steel will have ferrous materials in the plate. Always check the plate using a magnet. Steel can/will suck the air out of the music.

Brass plates are not as bad as steel but can still can have an impact on the SQ of the audio equipment.

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Here are a couple of links on the subject..

http://www.audioasylum.com/audio/tweaks/messages/127995.html

Posted by Al Sekela (A) on February 10, 2006 at 09:53:28

I just finished a five-way comparison of outlet cover plates (on 2-gang metal box):

1. no outlet plate (old standard);
2. magnetic SS outlet plate with Nylon screws (verified not grounded with ohmmeter);
3. same, but with one steel screw to ground it;
4. same as 3. with magnets stuck to outside of plate;
5. High-abuse Nylon plate with Nylon screws. Also tested with both 2-gang boxes covered with Nylon plates.

Test CD was Shirley Horn, _You Won’t Forget Me_, Verve 847 482-2.

Numbers 1 and 5 were so close I decided to leave the Nylon plates in place.

Number 2 gave an added sense of air and resonance, which led me to test the SS plate for acoustic ringing.

It rings like a bell with a pure, sweet, high sustained tone, and a lot of atonal immediate crash like a cymbal. With this thing vibrating near the outlet and not grounded, it is acting like a dynamo and converting acoustic vibration into electrical noise within the power circuit and/or safety earth.

Numbers 3 and 4 dulled the sound compared to number 1: not in the sense of lost treble, but in a lack of midrange presence. With my system tuned up, I can hear Shirley smile as she sings, "...should there be eyes like [:)]yours..." near the beginning of track 12, "You Stepped Out of a Dream." This sense of a smile was diminished with treatments 3 and 4. The piano tone was also less appealing in general.

Her voice seemed less cohesive over her range.Thus, my results are similar to yours with respect to grounded versus floating plates, but I believe the apparent improvement with the ungrounded plate is due to euphonic coloration rather than increased detail retrieval. You can confirm this by listening carefully with the ungrounded plate in place, and then with it removed. Other inmates have observed improved performance with no plate at all on the outlet, but clearly this is not safe for most people and violates code. In my case, anyone who approached the uncovered outlets would probably have died from tripping over the equipment and cables before reaching the outlets, so I was not concerned about the safety aspect. The Nylon plates’ appearance matches the other outlets in the room, so I will leave them on.

Al Sekela

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http://db.audioasylum.com/cgi/m.mpl?forum=tweaks&n=79013&highlight=oyaide+outlet+cover+plate...=

Posted by rcrump ( M ) on March 21, 2003 at 01:28:05
In Reply to: Genuine insanity: What kind of cover plate do I need? posted by rhizomatic on March 20, 2003 at 09:10:15:

I made some power strips probably fifteen years ago using some black plastic boxes and ordered some really beautiful cast brass plates for the fourplex boxes only to find that the solid brass made the sound just bright as the devil....A couple of nylon screws and some tape on the backside of the plate took care of the problem....Aluminum doesn’t have that sort of problem BTW....

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I am still using the P&S nylon duplex plates.

bflowers said:

System incorporates isolated grounds and IG outlets.

Is the branch circuit wiring installed in metal conduit? Steel or aluminum?

IF yes, does each dedicated branch circuit have its’ own dedicated conduit? A true dedicated branch circuit should never occupy the same raceway, conduit, with other branch circuit wiring.

What is the type of branch circuit wiring the electrician installed?

Example:

Metal conduit with wires installed inside the conduit/s after the conduit was installed?

>

MC or AC armored cable?

http://www.southwire.com/commercial/metalCladCables.htm

Aluminum or steel armor? Solid or stranded conductors?

>

NM-B sheathed cable? (Romex is a trade name)

>

What size of conductors, wires?

Approximate length of the dedicated branch circuit runs from the electrical panel to the wall outlets?

Number of dedicated branch circuits?

Are all the branch circuits, that feed audio equipment connected together by wire interconnects, fed from the same line, leg, in the electrical panel? All from Line 1 or all from Line 2? Not from both L1 and L2.

The advantage I have is that I know how my system should should because I only changed one piece of equipment from my old to new room.

How about the branch circuit wiring in the old room? Was the same type wiring used in the new room? How about the wall rough-in outlet boxes used in the new room compared to the old room. Same? Steel or plastic/fiber boxes?

How about the duplex receptacles. Same as the old room? Duplex cover plates. Same as the old room?

What manufacture, series, style, IG (Isolated Ground) type duplex receptacles did the electrician install? Duplex cover plates installed?

Room acoustics are a bit different,

.....

Jim