Pipe Electrode was Water Pipe Electrode GEC

[W@ttson]

Hello,

So 250.66 says that if you have a pipe electrode then the size of the GEC does not need to be >6AWG (similar to ground rod). However, I have seen that people require a #4AWG to a water pipe for a 200A service. Is a water pipe a special type of pipe that needs to be sized to the full size of 250.66? If you do have a number #4AWG to a water pipe, I assume you can connect a rebar #4AWG to it as a location for its boding jumper to terminate as permitted by 250.68( C ) (1)?

 

[augie47]

Hello,

So 250.66 says that if you have a pipe electrode then the size of the GEC does not need to be >6AWG (similar to ground rod). However, I have seen that people require a #4AWG to a water pipe for a 200A service. Is a water pipe a special type of pipe that needs to be sized to the full size of 250.66?

Our POCO require #4 (no idea why)

If you do have a number #4AWG to a water pipe, I assume you can connect a rebar #4AWG to it as a location for its boding jumper to terminate as permitted by 250.68( C ) (1)?

Yes

 

[infinity]

You're asking about two different types of electrodes, a pipe or rod electrode (one type) and a water pipe electrode (other type). The pipe or rod only requires a maximum of a #6, the water pipe can require a GEC up to #3/0 based on 250.66.

 

[petersonra]

I never quite got why an UG water pipe needs such a huge wire while the same size pipe electrode w/o water can get by with a #6.

I also don't get why a long piece of rigid conduit UG is not an acceptable GE, while a similar UG water pipe is.

There must be something really special about water pipe.

And why a pipe electrode has to be driven to qualify as a GE, but an UG water pipe does not.

 

[don_resqcapt19]

The use of a full sized GEC to the metal under ground water pipe electrode is based on the fact that in the past, that was a complete metal system. There is a solid physical path via your GEC, and your neighbors GEC back to the utility neutral.
In areas that have the all metal water piping system is common you don't even notice any electrical issues where your service neutral is open.

Now, even where the water service to the building is metallic, it is unlikely that the water main is, so that physical metal path does not exist on new installations.

 

[W@ttson]

You're asking about two different types of electrodes, a pipe or rod electrode (one type) and a water pipe electrode (other type). The pipe or rod only requires a maximum of a #6, the water pipe can require a GEC up to #3/0 based on 250.66.

Wow, this right here totally cleared it up, and it was so obvious! 250.52 (A) (1) vs 250.52 (A) (5). Thank you!

 

[infinity]

Wow, this right here totally cleared it up, and it was so obvious! 250.52 (A) (1) vs 250.52 (A) (5). Thank you!

You're welcome. I agree when taken separately pipe electrode and water pipe electrode sounds like the same thing.

 

[kwired]

I never quite got why an UG water pipe needs such a huge wire while the same size pipe electrode w/o water can get by with a #6.

I also don't get why a long piece of rigid conduit UG is not an acceptable GE, while a similar UG water pipe is.

There must be something really special about water pipe.

And why a pipe electrode has to be driven to qualify as a GE, but an UG water pipe does not.

If it is only 10 feet of pipe in the earth, it may not be any more effective than a "pipe electrode".

Often it is more than 10 feet and years ago could even been a huge network of piping with miles of pipe all connected together - that has potential of being pretty low resistance to earth compared to just 10 feet of pipe.