Supplementary Grounding Electrodes

[anbm]

1. If the building grounding electrode system already has water metal pipe, building steel, UFER, one ground rod - all bond together....
the second ground rod (Supplementary Grounding Electrode) is not required, correct? Because the first ground rod is no longer the sole grounding electrode.

2. How or what tool will be used to meter ground resistance?

 

[infinity]

1) The single ground rod is supplemented by the CEE so it's qualifies as an electrode. Since there is a CEE the ground rod is not required.
2) There are a few different types of testers from a hand held to a 3 pole fall of potential tester.

Fall-of-Potential Measurement

The Fall-of-Potential test method is used to measure the ability of an earth ground system or an individual electrode to dissipate energy from a site.

www.fluke.com

 

[anbm]

1) The single ground rod is supplemented by the CEE so it's qualifies as an electrode. Since there is a CEE the ground rod is not required.
2) There are a few different types of testers from a hand held to a 3 pole fall of potential tester.

Fall-of-Potential Measurement

The Fall-of-Potential test method is used to measure the ability of an earth ground system or an individual electrode to dissipate energy from a site.

www.fluke.com

Thanks, what is CEE?

 

[Strathead]

Thanks, what is CEE?

Concrete encased electrode. Many of us call it a UFER named after the person who "discovered" it.

 

[infinity]

Thanks, what is CEE?

The proper name for a Ufer is a Concrete Encased Electrode (CEE).

 

[anbm]

The proper name for a Ufer is a Concrete Encased Electrode (CEE).

So without CEE, we need second ground rod?

 

[infinity]

So without CEE, we need second ground rod?

If the building steel electrode qualifies under 250.52(A)(2) it can supplement the single rod.

 

[Dennis Alwon]

So without CEE, we need second ground rod?

It gets a bit confusing so I will try and complicate it some more.

If you only have a metallic water line that is in the ground for 10' of more then you need to supplement it. There are many choices but some electricians just drive 2 rods and they are done with it.

If you are able to get a concrete encased electrode installed then you don't need any rods and if there is a metallic water line you would still need that to be a part of the grounding electrode system. So in a sense you have used the water line as an electrode and that must be supplemented and it could be supplemented by a concrete encased electrode or 2 rods, or a few other methods.

 

[anbm]

It gets a bit confusing so I will try and complicate it some more.

If you only have a metallic water line that is in the ground for 8' of more then you need to supplement it. There are many choices but some electricians just drive 2 rods and they are done with it.

If you are able to get a concrete encased electrode installed then you don't need any rods and if there is a metallic water line you would still need that to be a part of the grounding electrode system. So in a sense you have used the water line as an electrode and that must be supplemented and it could be supplemented by a concrete encased electrode or 2 rods, or a few other methods.

If the building has metallic water pipe, concrete encased electrode, why we need (2) additional ground rods? not one or none?

 

[Dennis Alwon]

If the building has metallic water pipe, concrete encased electrode, why we need (2) additional ground rods? not one or none?

You don't. The concrete encased electrode will be the supplement for the water pipe. Think of it this way-- the water pipe is a good electrode however it is often replaced or parts of it replace to where the pipe may no longer be an electrode. This is why the water pipe needs to be supplemented by any of the other electrode choices. Rods are usually the easiest when dealing with existing buildings.

 

[Dennis Alwon]

If there is no metal water pipe then we would only need a concrete encased electrode, assuming there are no other electrodes available.

 

[Strathead]

The if-then logic diagram for article 250 would exceed the capability of many computers!