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BANGKOK 19 July 2019 22:03
myjawe

Electrical problem, socket not grounded/earthed, house not grounded/earthed, no electric wire to put on a nail behind the washing machine ?

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Posted (edited)
6 hours ago, RocketDog said:

In the end, a ground rod is a ground rod. Rebar inside concrete posts is just that since nobody ever makes an effort to ensure that the rebar is in proper contact with earth

It would seem that you do not understand what a Ufer earth is.

 

The rebar is not in contact with the Earth, the concrete with enough rebar inside a sufficient amount of concrete is a good earth. Concrete is not a good electrical insulator.

 

If your all your foundation rebar is connected and your foundations are big enough for a Ufer earth and the soil structure/moisture conditions are correct  a ground rod is just icing on the cake.

Edited by sometimewoodworker

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6 hours ago, Parsve said:

And do not listen to those who say that you should connect it to the structure steel they do not know what they are talking about.

Structural steel can be use an earth please check the work of Herbert G. Ufer and the US electrical code that in some states require a Ufer ground.

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20 hours ago, Parsve said:

I have never talked about putting the rod on the roof, could you please explain as you cite my comment. And ground and zero is for sure the same. If you look in your switchboard you will see they are connected.

Attention all readers of my post:

 

PARSVE never mentioned lightning rods in his post. That was entirely my comment.

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14 hours ago, sometimewoodworker said:

Structural steel can be use an earth please check the work of Herbert G. Ufer and the US electrical code that in some states require a Ufer ground.

Maybe so, but I've never personally lived in or seen a house in the USA that used structural steel. I guess it's a question of the income class I'm in! Most homes in the USA are 'stick built', meaning wood.

 

I'll investigate Ufer grounds next time I build a steel house though.

 

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14 hours ago, sometimewoodworker said:

It would seem that you do not understand what a Ufer earth is.

 

The rebar is not in contact with the Earth, the concrete with enough rebar inside a sufficient amount of concrete is a good earth. Concrete is not a good electrical insulator.

 

If your all your foundation rebar is connected and your foundations are big enough for a Ufer earth and the soil structure/moisture conditions are correct  a ground rod is just icing on the cake.

I can buy a copper rod and a piece of wire at any hardware store. The path to ground is as long as the wire. No concrete or rebar needed.

 

To imply that concrete is as conductive as soil is simply disengenous. I'm not saying Ufer systems don't serve, but I am saying concrete and dirt are different things, and earth is highly ionic and much more conductive than concrete. Copper is more conductive than iron. These are indisputable facts.

 

You can have the last word. I'm bored with the conversation.

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Just to throw my input into the mix. Our home is concrete and steel, we also have the requisite 2.4m copper-clad-steel rod (there's no way you would drive a pure copper rod this long, copper is just far too soft [and expensive]).

 

Whilst the re-bar was not designed to be electrically continuous there is so much of it and there are many (many) wired crossings. The actual integrity was demonstrated by the chaps welding the roof steel, the welder return was attached to a bit of rebar at ground level, only one wire needed up to the torch.

 

Using an earth resistance tester (yes, a proper one) the roof steel actually provides a rather better ground than the driven rod 🙂

 

Both linked (the rod keeps the PEA inspector happy) and we have a more than solid earth.

 

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And some more for the mix . .

 

Back in WW2 the Yanks were having problems with lighting blowing up bomb storage units and needed a way to dump natures huge electrical pulses before they got into the TNT.

 

Herbert Ufer observed that the high PH of concrete would provide a ready supply of ions and in turn provide a better electrical ground than almost any type of soil. Ufer also found that the soil around the concrete became doped and the rise in pH caused the overall impedance of the soil itself to be reduced. The concrete enclosures also increases the surface area of the connection between the grounding conductor and the surrounding soil further helping to reduce overall impedance of the connection.

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1 hour ago, RocketDog said:

To imply that concrete is as conductive as soil is simply disengenous. I'm not saying Ufer systems don't serve, but I am saying concrete and dirt are different things, and earth is highly ionic and much more conductive than concrete. Copper is more conductive than iron. These are indisputable facts.

I don't imply that a US army consultant found that 

 

Quote

In 1942, Herbert G. Ufer a consultant working for the U.S. Army. He discovered that concrete had better conductivity than most types of dry soil.

 

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1 hour ago, RocketDog said:

Maybe so, but I've never personally lived in or seen a house in the USA that used structural steel. I guess it's a question of the income class I'm in! Most homes in the USA are 'stick built', meaning wood.

So none of the houses you have seen have reinforced concrete  foundations? You must have had blinkers on whenever you have looked at a building site. 

 

The steel in the foundations is the only steel that matters, unless you are talking about lightning protection, other steel just makes a convenient point to attach to. 

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1 hour ago, sometimewoodworker said:

So none of the houses you have seen have reinforced concrete  foundations? You must have had blinkers on whenever you have looked at a building site. 

 

The steel in the foundations is the only steel that matters, unless you are talking about lightning protection, other steel just makes a convenient point to attach to. 

So you've never seen houses in the south or locations with heavy clay or bentonite soil that sit on pier foundations. But wait, often the foundation support blocks are concrete, so I can bore a hole in them for a ground instead of just driving a rod in the ground like such houses normally do. It's just so intuitive. I love it. This could revolutionize the building industry. But wait, my house in America has a slab foundation but also features a metal ground rod immediately below the breaker box. Poor ignorant savages.

 

OK, I'll just bore holes in the concrete slab floor and find some rebar.

Or maybe just push some wire into the hole and patch over with more concrete.

 

So much easier than pounding a rod into the ground, and a great topic for party conversation.

 

Great idea. It just keeps getting better.

 

Next time I pour a house foundation I'll drop a wire in it.

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19 minutes ago, RocketDog said:

Next time I pour a house foundation I'll drop a wire in it.

For future reference :-

 

ground.jpg.9206fe58abe6d9889f9fb58ba0576c76.jpg

 

 

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Posted (edited)
3 hours ago, RocketDog said:

So you've never seen houses in the south or locations with heavy clay or bentonite soil that sit on pier foundations.

Something like this ?

IMG_0314.JPG.0a601cbef815bc592c7007ec9cfebbd2.JPG

This has a great enough area for an excellent Ufer earth.

 

3 hours ago, RocketDog said:

But wait, often the foundation support blocks are concrete, so I can bore a hole in them for a ground instead of just driving a rod in the ground like such houses normally do. It's just so intuitive.

Nobody has ever suggested that that will work. You have to connect to the rebar in the foundations for stick build and that needs to be done during construction.

Quote

A new exception was added to 250.50 in the 2005 NEC, which states that concrete-encased electrodes are not required for existing buildings or structures where the conductive steel reinforcing bars aren't accessible without disturbing the concrete.

 

3 hours ago, RocketDog said:

But wait, my house in America has a slab foundation but also features a metal ground rod immediately below the breaker box. Poor ignorant savages.

I agree completely with you and your characterising of your fellow countrymen. Who can't/don't read your own electrical codes.

 

3 hours ago, RocketDog said:

Next time I pour a house foundation I'll drop a wire in it.

Done correctly as @Fruit Trader has shown you it is code compliant and correct, further it isn't going to degrade as your earth spike will.

 

Just because you can't understand/can't be bothered to read the US electrical code and the abundance of information showing that concrete-encased electrodes (Ufer ground) works and is now required 

 

Quote

if a new building contains rebar in the footing or foundation, it must be used as a grounding electrode. This electrode would serve as the supplement water pipe electrode that is required by 250.53(D)(2).

 

Note: Ground rods will no longer be necessary for most new construction, since virtually all new construction uses concrete encased reinforcing bars or rods in the foundation. Since they exist, they must be bonded to and used as part of the grounding electrode system. 

This could mean that your information dates from the Jurassic 😉 or at a minimum before 1975.

 

Quote

The steel reinforcing bar concrete-encased electrode was first introduced in the 1975 NEC.

 

Edited by sometimewoodworker

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This is a diagram of a safe installation. The panel has a ground rod that grounds the earth bar and incoming neutral. All circuits have a separate ground wire that provides a low impedance path for fault currents, ensuring the breakers open and remove the voltage from the faulted appliance. Also, there is an earth leakage breaker before the main circuit breaker.

 

post-45135-0-23261900-1388647418.png

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And now, as seems to happen with most threads concerning earthing I'm going to close this. 

 

Our OP has his answer.

 

:mfr_closed1:

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