Electrical Panel Grounding

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

Thanks - you are correct. I will hire a real expert. Bill