Grounding electrode system

[joeyww12000]

When building the grounding electrode system for a new construction service you must use all grounding electrodes available.....steel, ccee, groundrod, first 5ft of water pipe......You can either take one grounding electrode conductor to first electrode then bond each seperate electrode or take seperate grounding conductors to each electrode....my question is does the connection point at the service for your grounding electrode conductors have to be made at the grounded conductor bonding point of your service? Say you have a disconnect outside where your grounded conductor makes its bond and a system bonding jumper is ran inside to a MDP and terminated to the enclosure....can you make your terminations for your grounding electrode conductors in the MDP...? or must they all be taken outside to the service disconnect?

 

[chris kennedy]

Mornin Joey,

Did you read this?

250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).
(1) General. The grounding electrode conductor connection shall be made at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.

 

[joeyww12000]

so if multiple grounding electrode conductors are used then each must terminate at the service disconnecting means where the grounded conductor is bonded..... thanks....actually this would be the easiest place....as far as I can tell

 

[Smart $]

so if multiple grounding electrode conductors are used then each must terminate at the service disconnecting means where the grounded conductor is bonded...

Actually, NO.

GEC's can be "bonded and branched" at any point along their route. Only an individual-electrode GEC is permitted to be smaller than indicated in Table 250.66.

 

[joeyww12000]

Ok so, if I made a grounded/neutral conductor bond at my disconnect outside the building to a groundrod....my system bonding jumper going inside the building with my phase conductors to the MDP could terminate to the MDP can, then I could bring out seperate GEC's from that point? I understand I could bring a GEC out to say building steel, then from there daisy chain to other grounding electrodes.....is that what your saying? Im asking does my GEC always come from the grounded/neutral conductor bonding point at the first means of disconnect?

 

[raider1]

Im asking does my GEC always come from the grounded/neutral conductor bonding point at the first means of disconnect?

Did you read the code section that Chris posted?

Here it is again.

250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).
(1) General. The grounding electrode conductor connection shall be made at any accessible point from the load end of the service drop or service lateral to and including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means.

my system bonding jumper going inside the building with my phase conductors to the MDP could terminate to the MDP can,

You don't have a system bonding jumper running between the service disconnecting means and the MDP. What you have is an equipment grounding connductor.

A system bonding jumper is what is used to establish the neutral to ground connection for a separatetly derived system. Here is the definition of system bonding jumper from the NEC.

Bonding Jumper, System. The connection between the grounded circuit conductor and the equipment grounding conductor at a separately derived system.

Chris

 

[joeyww12000]

Thanks for making it clear about the difference between a system bonding jumper and a EGC....... OK now to my GEC connection point....I could not connect my GEC's to the MDP can since it's past the first point of disconnect, but anywhere in front of the disconnect past the load end of the service drop..?

 

[raider1]

Thanks for making it clear about the difference between a system bonding jumper and a EGC.......

Your welcome, it is important to know the correct terminology.

OK now to my GEC connection point....I could not connect my GEC's to the MDP can since it's past the first point of disconnect, but anywhere in front of the disconnect past the load end of the service drop..?

Correct, you can make your GEC connection to the grounded conductor at any accessible location at or ahead of the service disconnecting means. You are not permitted to install it after the service disconnecting means.

Chris

 

[joeyww12000]

the job im on the grounded/neutral conductor is bonded at the disconnect outside and in the mdp there is a grounding electrode conductor out to the building steel and waterpipe connected to the grounded/neutral conductor.... I study study study, then I get to work and men 15 to 20 years older than me are doing everything wrong and I second guess my knowledge...its getting old working with unprofessional people

 

[Smart $]

Correct, you can make your at any accessible location at or ahead of the service disconnecting means. You are not permitted to install it [GEC connection to the grounded conductor] after the service disconnecting means.

While that is correct, there is no prohibition to routing and bonding the GEC to downstream equipment while en route to the bonding point. The conductor is therefore a dual purpose GEC/EGC.

For example, a GEC routed from interrior electrodes—such as structural steel and water supply—can be routed through and bonded to the the MDP can/ground bus (but isolated from the grounded conductor), then run to the exterior service diconnect where it is bonded to the grounded conductor and exterior electrode's GEC.

 

[joeyww12000]

So are you saying you I could take loose the GEC from the grounded/neutral conductor in the MDP and connect it to the MDP can and it would be correct?

 

[raider1]

While that is correct, there is no prohibition to routing and bonding the GEC to downstream equipment while en route to the bonding point. The conductor is therefore a dual purpose GEC/EGC.

For example, a GEC routed from interrior electrodes?such as structural steel and water supply?can be routed through and bonded to the the MDP can/ground bus (but isolated from the grounded conductor), then run to the exterior service diconnect where it is bonded to the grounded conductor and exterior electrode's GEC.

Yes, you are correct.

I should have said it is not permitted to make the final connection of the GEC to the grounded conductor after the service disconnecting means.

Chris

 

[raider1]

So are you saying you I could take loose the GEC from the grounded/neutral conductor in the MDP and connect it to the MDP can and it would be correct?

The GEC must terminate to the grounded conductor at or ahead of the service disconnecting means. It can not just terminate to the MDP can after the service disconnecting means.

Chris

 

[joeyww12000]

Ok lets back up to make sure I got this here....I have a disconnect outside the building....from the grounded/neutral conductor bonding point inside the can there is a grounding electrode conductor out to a groundrod......going out of the disconnect there is a EGC from the grounded/neutral conductor bonding point going into the MDP and bonded to the enclosure.......from here are you saying you can go from the enclosure out to the steel and waterpipe with another ground....?

 

[raider1]

from here are you saying you can go from the enclosure out to the steel and waterpipe with another ground....?

No, you can't terminate the required grounding electrodes to the can of equipment downsteam from the service disconnecting means.

Chris

 

[joeyww12000]

Ok how about this.......If I were to do a service from scratch that contains a disconnect outside the building with a MDP inside I would do this......tell me if you agree or disagree...bare with me.....I would at the disconnect bond my grounded/neutral conductor by bonding to the enclosure and taking a GEC out to groundrod. I would then take an EGC that is connected to the grounded/neutral conductor bonding point out to my MDP along with the grounded neutral conductor keeping them seperated at the MDP. I would by whatever means need to get all other GEC's into the disconnect to terminate there.

 

[Smart $]

No, you can't terminate the required grounding electrodes to the can of equipment downsteam from the service disconnecting means.

Chris

You can if you run a GEC sized to 250.66 from the service disconnect to the MDP can. Note one or more other GECs coming into the can from additional electrodes must either bond directly to the GEC from the disconnect (i.e. you can't use the can as a bus), or all must terminate on a grounding bus with a cross-sectional area equal to or greater than that required for the GEC or the equivalent if of a different material (i.e. cu vs. al).

Also note running a GEC from the service disconnect to the MDP also serves the purpose of bonding equipment. Therefore a separate EGC is not necessary.

I just got done saying this in my last post and you agreed... and turned right around and contradicted yourself. Granted, joey used the term EGC... but many times you just have to "read" a poster's intentions, because they are trying to ask something about which they are uncertain... similar to trying to find the meaning of a word in the dictionary but uncertain of its spelling :smile:

 

[raider1]

Ok how about this.......If I were to do a service from scratch that contains a disconnect outside the building with a MDP inside I would do this......tell me if you agree or disagree...bare with me.....I would at the disconnect bond my grounded/neutral conductor by bonding to the enclosure and taking a GEC out to groundrod. I would then take an EGC that is connected to the grounded/neutral conductor bonding point out to my MDP along with the grounded neutral conductor keeping them seperated at the MDP. I would by whatever means need to get all other GEC's into the disconnect to terminate there.

Sounds good to me.

Chris

 

[raider1]

You can if you run a GEC sized to 250.66 from the service disconnect to the MDP can. Note one or more other GECs coming into the can from additional electrodes must either bond directly to the GEC from the disconnect (i.e. you can't use the can as a bus), or all must terminate on a grounding bus with a cross-sectional area equal to or greater than that required for the GEC or the equivalent if of a different material (i.e. cu vs. al).

Also note running a GEC from the service disconnect to the MDP also serves the purpose of bonding equipment. Therefore a separate EGC is not necessary.

I just got done saying this in my last post and you agreed... and turned right around and contradicted yourself. Granted, joey used the term EGC... but many times you just have to "read" a poster's intentions, because they are trying to ask something about which they are uncertain... similar to trying to find the meaning of a word in the dictionary but uncertain of its spelling :smile:

You can pass a GEC through the MDP and connect it to the can, but the GEC must ultimatly terminate to the grounded conductor at or ahead of the service disconnecting means.

When I said you can't terminate (end) the GEC at the MDP I meant that that could not be the final connection point of the GEC.

Chris

 

[buddhakii]

Thanks guys. I have been wondering for awhile know if a conductor can serve as both a gec and a egc. This question came up on a job a couple years ago and I never did get a definate answer. Should've came sraight here.