GEC

[wwhitney]

So, what is the correct name for the grounding conductor that runs along with the service conductors?

Generally there isn't one, the grounded service conductor is used for bonding on the utility side of a service disconnect. For example, in the SEB, is grounded service conductor bonded to the box?

See 250.92.

Cheers, Wayne

 

[infinity]

The GEC is the grounding conductor ahead of the service disconnect. I think I was wrong about the GEC.

The GEC (grounding electrode conductor) is used to connect the system neutral to the grounding electrode system (GES). The GES is typically made up of interconnected electrodes like a metal water pipe, concrete encased electrode (CEE), ground rods, building steel, etc.

So, what is the correct name for the grounding conductor that runs along with the service conductors? Is it the EGC?

There is no conductors other than the ungrounded conductors and the neutral ahead of the service disconnect. At the servcie disconnect the MBJ is installed. All "ground wires" after that point are EGC's.

Can you tell me the code section about this? That is the answer i try to find out.

Look at 250.6. Also 310.10(G)(1) regarding parallel conductors.

 

[roger]

Can you tell me the code section about this? That is the answer i try to find out.

Here's a simple single phase illustration showing current in both the EGC and Neutral.


The simple fix is to just do away with the unneeded conductor.

 

[binwork91]

Look at 250.6. Also 310.10(G)(1) regarding parallel conductors.

250.6 is about objection current. i think it is apply to the load side of service switch.
it is the question I ask at #15

I’m a bit confused about the following two scenarios:

1. A tap section in the switchboard feeds a 400A service switch using one 600 MCM copper conductor per phase and neutral, along with a 1/0 copper ground conductor in a 4" conduit. The 1/0 Cu is connected to the ground bus inside the 4000A switchboard. You mention it is violation per 250.6 Objection current.

2. Similar to scenario 1, but there is no 1/0 copper grounding conductor in the 4" conduit. Instead, the 4" conduit is bonded to both the upstream switchboard and the 400A service disconnect. Both pieces of equipment have their ground, neutral, and enclosure bonded together. I think that is how it install for the equipment. if i am wrong, please let me know.

Does the bonded conduit serve the same function as the 1/0 copper grounding conductor in scenario 1?"

And 310.10(G)(1).
The question becomes how you name the grounding conductor. If you call it a 'neutral,' then it needs to be the same size as the other neutral conductors. But if it's an equipment grounding conductor (EGC), it can be a different size than the neutral.

 

[binwork91]

Here's a simple single phase illustration showing current in both the EGC and Neutral.

View attachment 2578287
The simple fix is to just do away with the unneeded conductor.

In your picture, there is an EGC with the service conductors.


I know it's easy to ask the contractor to remove an unnecessary conductor, but the question is: why should they remove it—especially if it's already been installed? I need to find a solid reason for that.

 

[infinity]

In your picture, there is an EGC with the service conductors.


I know it's easy to ask the contractor to remove an unnecessary conductor, but the question is: why should they remove it—especially if it's already been installed? I need to find a solid reason for that.

Rogers graphic is showing what happens when you put a conductor that shouldn't be there in parallel with the neutral. This is specifically prohibited and remedied by 250.6(B)(1).

 

[wwhitney]

The question becomes how you name the grounding conductor. If you call it a 'neutral,' then it needs to be the same size as the other neutral conductors.

Again, there isn't generally a separate grounding conductor on the utility side of a service disconnect. Absent parallel conductors, a single conductor performs the role of both service neutral/grounded conductor and bonding conductor.

In your picture, there is an EGC with the service conductors.

Yes, that picture illustrates the wrong way to do it, and why it is wrong. The pictured "EGC" is just in parallel with the service neutral, and thus will carry neutral current. That violates 250.6, and 200.2 (on the theory that as the "EGC" is carrying neutral current, it is a grounded conductor, and so 200.2 applies).

Cheers, Wayne

 

[binwork91]

Rogers graphic is showing what happens when you put a conductor that shouldn't be there in parallel with the neutral. This is specifically prohibited and remedied by 250.6(B)(1).

But if there is not a EGC, is the conduit work same as EGC, because it bond at service panel and meter enclosure?

 

[don_resqcapt19]

250.6 is about objection current. i think it is apply to the load side of service switch.
it is the question I ask at #15

I’m a bit confused about the following two scenarios:

1. A tap section in the switchboard feeds a 400A service switch using one 600 MCM copper conductor per phase and neutral, along with a 1/0 copper ground conductor in a 4" conduit. The 1/0 Cu is connected to the ground bus inside the 4000A switchboard. You mention it is violation per 250.6 Objection current.

2. Similar to scenario 1, but there is no 1/0 copper grounding conductor in the 4" conduit. Instead, the 4" conduit is bonded to both the upstream switchboard and the 400A service disconnect. Both pieces of equipment have their ground, neutral, and enclosure bonded together. I think that is how it install for the equipment. if i am wrong, please let me know.

Does the bonded conduit serve the same function as the 1/0 copper grounding conductor in scenario 1?"

And 310.10(G)(1).
The question becomes how you name the grounding conductor. If you call it a 'neutral,' then it needs to be the same size as the other neutral conductors. But if it's an equipment grounding conductor (EGC), it can be a different size than the neutral.

Objection current is any current outside of the circuit conductors and that can happen on either the line or load side of the service equipment.
1...you do not install any type of grounding conductor with the service conductors.
2...The 400 amp service disconnect needs a main bonding jumper and a connection to a grounding electrode system. The metal conduit is actually in parallel with the neutral by code rule and will carry current. While that is objectionable current, it happens on a code compliant installation where there is a metal raceway between the metering, or other equipment and the service disconnect.
There is no function for the copper grounding conductor in #1.
If the conductor is connected to the same points as the neutral at each end, it is in parallel with the neutral and a violation unless it is the same size as the neutral.

 

[don_resqcapt19]

But if there is not a EGC, is the conduit work same as EGC, because it bond at service panel and meter enclosure?

Equipment grounding conductors do not exist on the line side of a service disconnect. They only exist on the load side of the main bonding jumper.

 

[binwork91]

1...you do not install any type of grounding conductor with the service conductors.

Is there any code prohibit to install grounding conductor with service conductors?

2...The 400 amp service disconnect needs a main bonding jumper and a connection to a grounding electrode system. The metal conduit is actually in parallel with the neutral by code rule and will carry current. While that is objectionable current, it happens on a code compliant installation where there is a metal raceway between the metering, or other equipment and the service disconnect.
There is no function for the copper grounding conductor in #1.

It convinced me.

If the conductor is connected to the same points as the neutral at each end, it is in parallel with the neutral and a violation unless it is the same size as the neutral.

So, you think it is neutral. if it is neurtral, I agree with you.
But Is there any code prohibit to install grounding conductor with service conductors?




Sorry if I'm being annoying...

 

[binwork91]

If the conductor is connected to the same points as the neutral at each end, it is in parallel with the neutral and a violation unless it is the same size as the neutral.

Thank you. I think you are right. it will become a neutral conductor. per definitions:

Neutral Conductor. The conductor connected to the neutral
point of a system that is intended to carry current under
normal conditions.

So if it is neutral, it needs to be same as as other neurtal.

 

[binwork91]

Thank you all.

 

[don_resqcapt19]

Is there any code prohibit to install grounding conductor with service conductors?
....
Sorry if I'm being annoying...

Exactly what would it be connected to at each end?