grounding electrode conductor

[Dennis Alwon]

Based on this thread https://forums.mikeholt.com/threads/gas-and-water-pipe-bonding.2575283/#post-2848700 it got me thinking. If I were to be responsible for the service lateral to the meter base and I sized it for voltage drop (500kcm conductors) and then used my standard size (4/0 conductors) from the meter to the panel, I then size my grounding electrode conductor based on????? the 500kcm or the 4/0... My guess is the 500kcm

 

[augie47]

By letter of the law I would agree, the 500. (I never enforced it that way).

 

[retirede]

My guess is the 4/0. But I don’t have any code reference.

 

[LarryFine]

Depends on what the GEC sizing is specifically based on.

 

[don_resqcapt19]

Based on the notes to Table 250.66, the sizing is based on the size of the service entrance conductors. In this application the service entrance conductors start at the load end of the service lateral conductors (utility owned) or underground service conductors (customer owned).

 

[Dennis Alwon]

Based on the notes to Table 250.66, the sizing is based on the size of the service entrance conductors. In this application the service entrance conductors start at the load end of the service lateral conductors (utility owned) or underground service conductors (customer owned).

It seems like you are saying that the lateral in this case is not service conductors. If so that would mean the service laterals (customer owned) are not service conductors.

I don't see any info in the Notes that will verify what you stated. The service conductors IMO, include the underground conductors. The power company conductors are always smaller so the table will always look at the largest.

 

[rojay]

Looking at the definitions, it seems that there is a distinction made between underground service conductors (or service lateral if utility owned) and service entrance conductors, underground system.
I’ve had a similar dilemma with the GEC sizing on a 400 amp service with twin 200’s.

 

[Dennis Alwon]

Looking at the definitions, it seems that there is a distinction made between underground service conductors (or service lateral if utility owned) and service entrance conductors, underground system.
I’ve had a similar dilemma with the GEC sizing on a 400 amp service with twin 200’s.

If you use 2 panels with 4/0 aluminum or 3/0 copper than a #2 grounding electrode conductor is needed based on note 1 of the table

 

[don_resqcapt19]

It seems like you are saying that the lateral in this case is not service conductors. If so that would mean the service laterals (customer owned) are not service conductors.

I don't see any info in the Notes that will verify what you stated. The service conductors IMO, include the underground conductors. The power company conductors are always smaller so the table will always look at the largest.

The notes all refer to "service entrance conductors" and those start at load end of the underground conductors. I am saying that the rule applies to service entrance conductors and not the more generic service conductors that would included the underground service conductors.

Service-Entrance Conductors, Underground System.
The service conductors between the terminals of the service equipment and the point of connection to the service lateral or underground service conductors. (CMP-4)

These are the notes I am talking about from Table 250.66.

Notes:
1. If multiple sets of service-entrance conductors connect directly to a service drop, set of overhead service conductors, set of underground service conductors, or service lateral, the equivalent size of the largest service-entrance conductor shall be determined by the largest sum of the areas of the corresponding conductors of each set.
2. Where there are no service-entrance conductors, the grounding electrode conductor size shall be determined by the equivalent size of the largest service-entrance conductor required for the load to be served.

Based on that, it is my opinion that you size the GEC based on the size of the service entrance conductors. In your case, that would be the conductors between the meter and the service equipment.
However the code language is not clear on what conductors are used to size the GEC.

 

[rojay]

If you use 2 panels with 4/0 aluminum or 3/0 copper than a #2 grounding electrode conductor is needed based on note 1 of the table

Agreed. Sometimes when I think 400 amp service, I get stuck in the default 1/0 AWG GEC mode based on using 500 or 600’s.

 

[rojay]

The notes all refer to "service entrance conductors" and those start at load end of the underground conductors. I am saying that the rule applies to service entrance conductors and not the more generic service conductors that would included the underground service conductors.

These are the notes I am talking about from Table 250.66.

Based on that, it is my opinion that you size the GEC based on the size of the service entrance conductors. In your case, that would be the conductors between the meter and the service equipment.
However the code language is not clear on what conductors are used to size the GEC.

Don,
Let’s say this was a 400 amp service w/ 2-200 disconnects. From the load side of the utility meter we run 600’s into a trough where we tap off with 3/0’s for each 200 amp panel. Since we aren’t directly connected to our underground service lateral per note 1 of Table 250.66, would you agree that a common GEC would need to be sized based on the 600’s?

 

[don_resqcapt19]

Don,
Let’s say this was a 400 amp service w/ 2-200 disconnects. From the load side of the utility meter we run 600’s into a trough where we tap off with 3/0’s for each 200 amp panel. Since we aren’t directly connected to our underground service lateral per note 1 of Table 250.66, would you agree that a common GEC would need to be sized based on the 600’s?

Yes, the 600s are service entrance conductors.

 

[Engser18]

Based on this thread https://forums.mikeholt.com/threads/gas-and-water-pipe-bonding.2575283/#post-2848700 it got me thinking. If I were to be responsible for the service lateral to the meter base and I sized it for voltage drop (500kcm conductors) and then used my standard size (4/0 conductors) from the meter to the panel, I then size my grounding electrode conductor based on????? the 500kcm or the 4/0... My guess is the 500kcm

Since you are saying GEC, then where is your GEC connected to? if it is rod/pipe/plate then it is based on 250.66 (A). (hint #6)

 

[rojay]

Yes, the 600s are service entrance conductors.

While I agree with your interpretation, I’d say by definition the 3/0 AWG tap conductors are service entrance conductors too. Do you have any insight as to why the sizing of the GEC is different based on if the 3/0 AWG tap conductors are directly connected to the service lateral in a meter can vs. spliced in a trough?

 

[don_resqcapt19]

While I agree with your interpretation, I’d say by definition the 3/0 AWG tap conductors are service entrance conductors too. Do you have any insight as to why the sizing of the GEC is different based on if the 3/0 AWG tap conductors are directly connected to the service lateral in a meter can vs. spliced in a trough?

Because it is based on the largest service entrance conductor and where you have a tap, the main conductor is the largest service entrance conductor. If you have two sets of conductors connected at the meter, the GEC would be based on the sum of the areas of the conductors connected in parallel.
The service lateral conductors or underground service conductors do not enter into to this as they do not meet the definition of service entrance conductors. The service entrance conductors, by definition, originate at the load end of those conductors.

 

[rojay]

Thanks for the clarification, much appreciated!

 

[Sberry]

I see someone asked about the electrode, rod or uffer. The head man in this state says he enforces this on cross section of service entrance conductor, poco looks like they connect a number 2 to this overhead. Not sure how much difference there is between a 4 and a 6 to a water pipe?

 

[don_resqcapt19]

I see someone asked about the electrode, rod or uffer. The head man in this state says he enforces this on cross section of service entrance conductor, poco looks like they connect a number 2 to this overhead. Not sure how much difference there is between a 4 and a 6 to a water pipe?

That is what the code requires.