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 Post subject: Better earth grounds
PostPosted: April 29th, 2020, 3:47 pm 
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Joined: February 28th, 2013, 3:31 pm
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I was just speaking with a friend who is a HAM about good grounds. There are now materials called grounding enhancement materials (GEM) that you can use in the soil to greatly reduce resistivity without the corrosive effects of old methods using salts like copper sulfate. Here are a couple of links.

https://www.erico.com/category.asp?category=R2387

https://www.gordonelectricsupply.com/p/ ... gLsr_D_BwE


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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 4:31 pm 
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Location: Baltimore MD
Thanks, Tom
I was always curious about what happens to the earthing properties over time with a ground rod.
This came at a good time because I want to sink a new ground rod right out my sound room's window.
I know its code to bond all grounds together but since my I have a dedicated sound room on its own circuit I plan to use only the new ground


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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 6:22 pm 
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Joined: July 24th, 2015, 4:17 pm
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Location: Parkville, Maryland
Pelliott321 wrote:
Thanks, Tom
I was always curious about what happens to the earthing properties over time with a ground rod.
This came at a good time because I want to sink a new ground rod right out my sound room's window.
I know its code to bond all grounds together but since my I have a dedicated sound room on its own circuit I plan to use only the new ground


Actually you are not on a separate "circuit." You have one service entrance from a nearby transformer to your house that feeds through the billing meter to your main panel-board.

That "circuit" still comes off one of two 120-vac single-phase feeds with reference to neutral that is tied to the house ground from the 240-volt service . You may have a circuit-breaker protected feed from your panel-board but it is only just that -- a protected feed. To do what you wish you would have to have a separate dedicated service entrance to the house.

Computer facilities and hospitals have what is know as an isolated ground system. The specialized receptacles (orange color) have your typical hot and neutral feeds, but the ground bond goes straight back to the service entrance.

Pictures speak louder than words -- attached is an illustration. And -- to ad insult to injury -- you can created a ground loop causing your audio system to "hum" the words.


Attachments:
Isolated Ground Illustation.jpg.png
Isolated Ground Illustation.jpg.png [ 37.96 KiB | Viewed 9309 times ]

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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 7:23 pm 
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Walt is absolutely correct about running alternate grounds from a sub panel. That will cause the code people to have a fit. However, there is nothing to say that you can't run a separate ground from, for example, the ground on a turntable arm. As Walt says, you may cause more problems with ground loops depending on where the alternate grounds are in relation to the main service feed ground. Other than violating codes, there is no one solution for lowest noise. As I found when running a USB DAC off my laptop, the internal laptop noise filter shunted noise from the inside of the laptop to the power supply ground which then traveled down the house ground wires to the amplifier causing noise. There was enough impedance in the house ground wires to cause the grounded body of the input jacks on the amp to pick up the noise. Having a super ground somewhere near the service panel would have done no good because the noise occurred on the ground wiring itself in the house walls before it got to the ground point. Finding noise sources and correcting the problems is one of the most difficult things.


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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 8:15 pm 
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Location: Baltimore MD
In an old house such as mine, I question the quality of the house ground.
Actually there are two. One to a water pipe and another to a small ground rod through the wall and into the ground outside. I have cleaned and tightened these connections but I still am suspicious of quality


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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 10:10 pm 
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tomp wrote:
Walt is absolutely correct about running alternate grounds from a sub panel. That will cause the code people to have a fit. However, there is nothing to say that you can't run a separate ground from, for example, the ground on a turntable arm. As Walt says, you may cause more problems with ground loops depending on where the alternate grounds are in relation to the main service feed ground. Other than violating codes, there is no one solution for lowest noise. As I found when running a USB DAC off my laptop, the internal laptop noise filter shunted noise from the inside of the laptop to the power supply ground which then traveled down the house ground wires to the amplifier causing noise. There was enough impedance in the house ground wires to cause the grounded body of the input jacks on the amp to pick up the noise. Having a super ground somewhere near the service panel would have done no good because the noise occurred on the ground wiring itself in the house walls before it got to the ground point. Finding noise sources and correcting the problems is one of the most difficult things.


I can't begin to complain about the hum chasing I have done over these many years. Even with a relatively modern house with a sweet 10-foot ground rod tied to my service and water pipes. Luckily that was in the past -- I chased the hum and caught it. :obscene-drinkingcheers:

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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 10:20 pm 
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Location: Parkville, Maryland
Pelliott321 wrote:
In an old house such as mine, I question the quality of the house ground.
Actually there are two. One to a water pipe and another to a small ground rod through the wall and into the ground outside. I have cleaned and tightened these connections but I still am suspicious of quality


I expect that your water service is copper out to the billing meter. Your ground rod is considered the primary ground and the buried water-service copper the secondary ground with the two tied together.

The NEC states that the ground impedance cannot exceed 25-ohms. That's a recent change -- the earlier code requirement was that the ground resistance could not exceed 25-ohms. My vote is for resistance, but then that's just me.

I believe you are OK. Since your domestic water piping runs throughout your house you can tie to that for something more local to your audio area. That way it's a win-win. You meet code -- and you can possibly avoid a "hum job" (tee-hee).

With my house it's only the ground rod. My water service out to the billing meter is Polybutylene (another story).

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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 10:30 pm 
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My problem was that I was drawing power from separate circuits (breakers). Power amps ran on 220V and everything else on 120 V. This produced a lot of 60 Hz hum. I solved this with a star ground. I broke the 220 V ground and ran the amplifier ground wire to the 120 V outlet ground.


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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 10:33 pm 
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brombo wrote:
My problem was that I was drawing power from separate circuits (breakers). Power amps ran on 220V and everything else on 120 V. This produced a lot of 60 Hz hum. I solved this with a star ground. I broke the 220 V ground and ran the amplifier ground wire to the 120 V outlet ground.


It can be a damn frustrating Witch Hunt! :angry-banghead:

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 Post subject: Re: Better earth grounds
PostPosted: April 29th, 2020, 11:28 pm 
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8 foot ground rods should be considered supplemental only. Their impedance is ridiculously high; no matter how large the service (even 4000 amperes) the grounding electrode conductor to a driven rod never needs to exceed #6 AWG copper!!!!! The rod simply cannot conduct any more current.

Want a good ground besides the superb cold water ground? Use a Ufer ground. That is a foundation ground. If there isn't one in your house, the procedure is to dig a 20 foot long, two foot wide by two foot deep hole, install rebar, Cad weld the GEC to the rebar, and encase the assembly in concrete. That is a low impedance ground.

If you are going to drive a shitty ground rod and connect it to your stereo, consider this . Unless, you have a separately derived system (transformer coupled, galvanic isolation, no current path between primary and secondary windings) the ground you add is in parallel with the household grounding electrode system as well as the utility center tap of the transformer feeding the service.
So, if a ground fault occurs anywhere between the transformer and any branch circuit in the house, a portion of the fault current WILL flow through your stereo ground, perhaps right through your tonearm!

There are good reasons for the Code rules. Flout them at your own risk.

ALL GROUNDS IN A STRUCTURE NEED TO CONNECT TO THE GROUNDED CONDUCTOR (NEUTRAL) AT A SINGLE POINT UNLESS WORKING WITH A SEPARATELY DERIVED SYSTEM!


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