Service entrance conductors - grounding conductor

C

cppoly

Senior Member
Location
New York
Is there a code section that indicates a grounding conductor is not needed with service entrance conductors?

For a 120/208V, 3 phase, 4 wire service, there would only be 3 ungrounded conductors, 1 grounded conductor (neutral), and no grounding conductor right?
 
Yes only 4 conductors would be used
No EGC is required (or permitted in parallel with the neutral) to be run with service conductors because and EGC does not exist until after the point where the MBJ is installed. All bonding of metal parts ahead of the service disconnect is connected directly to the neutral.
 
Right. There is no EGC ahead of the service disconnect. All metallic enclosures and equipment are bonded by and to the neutral.
 
Thanks.

The utility transformer is pad mounted outside. These secondary conductors go into a meter (service point) and then into a disconnect switch, which are both right near the transformer outside. From the disconnect, conductors go underground into a building's main electrical panel. Would the conductors from outside disconnect to the main electrical panel require a grounding conductor?
 
For years the answer would be a simple "yes" and that is still the case other than for an "emergency disconnect" as required for dwellings per 230.85.
If the disconnect you reference is a "service disconnect" the an EGC is required on the load side.
IF it is a "emergency disconnect" (230.85) or a "meter disconnect" (230.82) then the EGC is not necessary until after the service disconnect
 
So I would just need to confirm if the disconnect by the transformer secondary is:

1) A service disconnect: (EGC would be required on the load side)
2) Emergency disconnect (EGC not required on load side)
3) Meter disconnect (EGC not required on load side)
 
I got my answer from the utility and they said the service point begins at the transformer secondary...... so then if there's a existing disconnect that is at the transformer secondary that was installed maybe 20+ years ago, this must be a service disconnect since an emergency disconnect is fairly new to the code cycle right??
 
cppoly said:
so then if there's a existing disconnect that is at the transformer secondary that was installed maybe 20+ years ago, this must be a service disconnect since an emergency disconnect is fairly new to the code cycle right??
Click to expand...
I would agree. The EM disconnect thing is from the 2020 NEC.
 
A Disconnect at a Transformers Secondary does not give us enough information as to whether or not an EGC is required with the conductors on the load side of that disconnect.

The determining factor for the requirement of the EGC would be if that disconnect also has the first means of overcurrent protection and where the grounding and bonding takes place deeming the conductors that are going into the building as a "Feeder" which would require an EGC whereas "Service Conductors" would not.

Jap>
 
jap said:
A Disconnect at a Transformers Secondary does not give us enough information as to whether or not an EGC is required with the conductors on the load side of that disconnect.

The determining factor for the requirement of the EGC would be if that disconnect also has the first means of overcurrent protection and where the grounding and bonding takes place deeming the conductors that are going into the building as a "Feeder" which would require an EGC whereas "Service Conductors" would not.

Jap>
Click to expand...

Jap thanks!

Do you have code section(s) to reference? I'm having a hard time finding service entrance conductors not requiring a grounding conductor.

So if this disconnect does not have OCPD then it is not a service disconnect? Then what is it?

If it's not a service disconnect and there's no OCPD, then would the neutral still be required to be bonded to case or would this not be allowed?
 
cppoly said:
Jap thanks!

Do you have code section(s) to reference? I'm having a hard time finding service entrance conductors not requiring a grounding conductor.

So if this disconnect does not have OCPD then it is not a service disconnect? Then what is it?

If it's not a service disconnect and there's no OCPD, then would the neutral still be required to be bonded to case or would this not be allowed?
Click to expand...

I'd have write a book just to try and explain the above. Lol!!!

Jokes aside, I would probably start with 250.186

Jap>
 
Equipment grounding conductors start at the location of the main bonding jumper. They do not exist on the line side of the main bonding jumper location.
 
cppoly said:
Jap thanks!

Do you have code section(s) to reference? I'm having a hard time finding service entrance conductors not requiring a grounding conductor.

So if this disconnect does not have OCPD then it is not a service disconnect? Then what is it?

If it's not a service disconnect and there's no OCPD, then would the neutral still be required to be bonded to case or would this not be allowed?
Click to expand...

So if this disconnect does not have OCPD then it is not a service disconnect? Then what is it?

A disconnect that disconnects Service Conductors.


If it's not a service disconnect and there's no OCPD, then would the neutral still be required to be bonded to case or would this not be allowed?

If the case wasn't bonded to the neutral at this point there would be no way to clear a fault since there would be no return path to the utility Xfmr.

Jap>
 
@jap , slightly confused now!

First, thank you for 250.186. Lol go figure the section I need is all the way at the END of article 250.

In Option 1, if the disconnect doesn't have an OCPD and it's not called a "service disconnect" but you indicate that neutral is bonded to the case - wouldn't bonding the neutral to the case be a main bonding jumper connection ? Then to @don_resqcapt19 point, if it has a main bonding jumper then it's a service disconnect??

Here's a quick sketch.

For option 1 (no OCPD):

1) Would the disconnect have a neutral?
2) You mentioned neutral is bonded to case
3) Just a disconnect switch, not a service disconnect switch
4) Main bonding jumper Y/N??
 

Attachments

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cppoly said:
@jap , slightly confused now!

First, thank you for 250.186. Lol go figure the section I need is all the way at the END of article 250.

In Option 1, if the disconnect doesn't have an OCPD and it's not called a "service disconnect" but you indicate that neutral is bonded to the case - wouldn't bonding the neutral to the case be a main bonding jumper connection ? Then to @don_resqcapt19 point, if it has a main bonding jumper then it's a service disconnect??

Here's a quick sketch.

For option 1 (no OCPD):

1) Would the disconnect have a neutral?
2) You mentioned neutral is bonded to case
3) Just a disconnect switch, not a service disconnect switch
4) Main bonding jumper Y/N??
Click to expand...
250.186 is in Part X, Grounding and bonding of systems and circuits over 1000 volts. Is your system over 1000 volts, if not, nothing in Part X of Article 250 applies to your installation.
 
I think it would be better for to decide whether you want three (service) conductors or four (feeder) conductors, then ask us the best way to go about it.
 
Sorry bout the wrong section, but, it's much the same concept.

Regardless, I'll generally choose where I want my Service Conductors to end and where I want my Feeder (which will include the EGC) to begin.

Sometimes I'll pull Service Conductors all the way to the structure and do my grounding and bonding there, and, sometimes I'll do my grounding, bonding and overcurrent protection out in the yard and pull a Feeder with an EGC to the structure.

Depends on the install.

Jap>
 
cppoly said:
Is there a code section that indicates a grounding conductor is not needed with service entrance conductors?

For a 120/208V, 3 phase, 4 wire service, there would only be 3 ungrounded conductors, 1 grounded conductor (neutral), and no grounding conductor right?
Click to expand...

cppoly said:
I got my answer from the utility and they said the service point begins at the transformer secondary...... so then if there's a existing disconnect that is at the transformer secondary that was installed maybe 20+ years ago, this must be a service disconnect since an emergency disconnect is fairly new to the code cycle right??
Click to expand...

I agree. You got your answer. Poco told you your service point begins at the transformer secondary. Done. So your disconnect switch must have Overcurrent protection outside where it originates at the transfer and must have a grounding conductor (or satisfy 250.118)
 
jap said:
A Disconnect at a Transformers Secondary does not give us enough information as to whether or not an EGC is required with the conductors on the load side of that disconnect.

The determining factor for the requirement of the EGC would be if that disconnect also has the first means of overcurrent protection and where the grounding and bonding takes place deeming the conductors that are going into the building as a "Feeder" which would require an EGC whereas "Service Conductors" would not.

Jap>
Click to expand...
That would not be correct. See 250.24(A)(5) and 250.142(B). It is the service disconnect that after which one needs an isolated grounded conductor. Note also the service OCPD must be 'immediately
jap said:
So if this disconnect does not have OCPD then it is not a service disconnect? Then what is it?

A disconnect that disconnects Service Conductors.
Click to expand...

Note if you have a disconnect, it typically MUST BE your service disconnect. Your only other option is to call it something that is listed in 230.82. Also if its a dwelling, and we are talking 2020 or 2023 code, it may be able to be called an emergency disconnect.
 
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