Electrical Panel Grounding

I have learned to appreciate the need for the one point of neutral tie in at the service panel and the tie to ground for lightening. And why the grounds must be tied together for safety,

One theory that lurks is; if all electric power seeks to return to the source, what is that source for the harmonic distortion and noise created by say a neighbors refrigerator or a faulty relay. And what about the energy used in powering a motor. That energy is not returning to the source. And why does the power get so quiet when it is really wet (rain) outside? These are my questions with my thinking that ground may have some influence as the "sump" theory goes. My local friend advocates a ground field of a half-dozen copper clad rods, each with a separate ground wire tie back to the main panel to lower ground resistance. He is a satellite engineer for the railroad, and is personally working on some changes to basic sigma-delta class D technology, so I do have some respect for his opinions.  

My outlets are PS Audio Blaun (sp?) that replace normal outlets with a double box, and have a machined aluminum face plate. They feed into twin PS Audio power regeneration units (one on the front-end and one for the power amps). The feed is not currently from the existing sub-panel and the sub-panel only feeds a set of outdoor receptacles powering the pond and water features that I can completely turn off during listening. So the plan is in formulation. And the sub-panel may need to be redone altogether.  I would only use lager gauge copper wire to create a dedicated audio feed. And historically, I used a metal (wound style) shield for the wiring from the sub-panel to the outlets, I bought my home with the existing wiring in place.

One oddity, at least to me, is that the existing sub-panel has the power take-off from the main panel by using two 20A breakers in the main panel. Both the main and sub-panel are less than 20' from the audio outlets.I always thought you just came off the main bus for sub-panel power.

I look forward to hearing your input.

wgutz,

The lower the Grounding Electrode, ( example, ground rod), to soil resistance the better. IEEE recommends 5 ohms or less, preferably 2 ohms or less.

It’s not the number of ground rods driven into the earth that will necessarily yield a 2 ohm soil resistance. A lot depends on the content/type of soil and soil moisture. Where you live can make a difference. The 4 seasons can greatly impact soil moisture. It is possible a single 5/8" X 20ft driven ground rod will have a lower ground resistance than 6 individual 5/8" X 8ft driven ground rods.

When multiple ground rods are driven into the earth they should all be tied/connected together with a single wire extended and connected to the electrical service entrance neutral conductor. The multiple ground rods then become a single Grounding Electrode.

Harmonics? The earth will not reduce harmonics.

The majority of harmonic noise found on the AC mains in a home are caused by electronic devices found in the home. Seldom will those produced in the neighbor’s house end up adding to the harmonic noise found in your house.


A refrigerator motor does not produce harmonic noise. Now the micro processor that controls the features on the refrigerator can.

Nonlinear loads produce harmonic noise back on the AC mains.
Examples of,

Switch mode power supplies
Light dimmers
Hair dryers
Computers
Variable frequency drive units found on many of the furnaces built today. (Controls blower motor speed)
Dual wattage portable electric space heaters.
CFL and LED lights
Electronic ballasts

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PS Audio power regeneration units.

Curious, have you ever checked if the outputs of the two units are in phase with one another? If you have a multi meter measure the voltage from the hot contact from one of the output receptacles on one units to the hot contact of an output receptacle on the other unit. If the outputs of the two units are in phase you should measure zero volts nominal. If out of phase you will measure 240Vac nominal.

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Sub Panel.

Don’t use it to feed your audio equipment. The wire feeding the panel is too small. Use the main electrical panel.

http://www.p3-inc.com/images/grounding_for_pq_wp2016_p3.pdf
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Testing soil resistivity

http://www.fluke.com/fluke/iden/solutions/earthground/soil-resistivity-method

Thanks for the info. I'll test the phase of my PS units when I have them close enough for my test leads.  

I have thought of pouring a concrete pier say 6' deep and 12" diameter mixing the concrete with an additive for conductivity. Do you know if graphite would work? I once knew but have since forgotten the correct additive.

There was an electrical testing facility here that dug out the entire parking lot about 12' deep and put in a conductive 4' thick conductive concrete pad full of rebar all tied together with what looked like bronze or copper clamps. It was at least 300' by 300' in size. I guess they wanted a low resistance ground.

Bill

I have thought of pouring a concrete pier say 6’ deep and 12" diameter mixing the concrete with an additive for conductivity.

I assume inside the concrete you would install at least #4 re-bar, copper wire/s, or a ground rod.

6ft is not very deep. Bare minimum for a ground rod per NEC code is 8ft. Again bare minimum. As a rule a single 8ft rod will not achieve a 5 ohm or less ground resistance even in good fertile farm soil.

What is the make up of soil like in Denver? How about on your property? Is it rocky and sandy? What is the average yearly moisture content in the soil? What is the resistivity of the soil?

How about the summer months. How much rain fall is there? How moist will the soil be from the surface of the earth to 6ft down? What will be the soil resistance of the soil all the way around your concrete encased grounding electrode? How many feet out in all directions around the grounding electrode? If the resistance is high, say above 5 ohms what good were all your efforts? It is possible the soil resistance could be 100 ohms more or less.

Is the soil corrosive? If yes that can determine what metal is used for an electrode.

If you are serious about supplementing the electrical grounding electrode system of the electrical service of your house I would suggest you hire a power quality expert from Denver that can test the soil resistance. He will be the best qualified to recommend best practices for your area. You may have to first start with a commercial/industrial electrical contractor.

It is possible the grounding electrode system you have now is adequate. It may need to be inspected for loose and or corroded connections. Do not do this yourself. Hire a qualified licensed electrical contractor.

Here is some more reading reading material for you.

https://www.engineereducators.com/docs/groundingandbonding2-2.pdf

http://www.cpccorp.com/deep.htm

I ran across this picture several years ago. I still get a laugh seeing it.
http://i.imgur.com/rbAo0Vc.jpg