Service Disconnects - Common GEC Connection Location (250.64)

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xguard

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Baton Rouge, LA
I have a panel that is fed by service entrance conductors, the panel is inside a building. The meter and CT's are mounted directly opposite on the outside of this same wall. Within the panel a circuit for a chiller chiller is connected to the service entrance conductors. They are connected using insulation piercing connectors. These unprotected conductors exit the panel and go outside to the chiller disconnect.

According to 250.64 (D)(3) the grounding electrode conductor for the two service disconnects, one the panel and the other the chiller disconnect, can be connected to each grounded conductor in a common location. Currently they are connected in the panel. The mentioned section specifies "...in a wireway or other accessible enclosure on the supply side of the disconnecting means....".

by supply side is the connection okay to be made in the panel as long as it's prior to being the grounded conductor being connected to the panel? Or does it need to be a separate enclosure ahead of both the panel and the chiller disconnect?

Thanks for any feedback.
 
In agree with don.
One solution would be to "tap" your service conductor outside at the meter for CTs and run them to a service disconnect at the chiller, load permitting .
 
augie47 said:
In agree with don.
One solution would be to "tap" your service conductor outside at the meter for CTs and run them to a service disconnect at the chiller, load permitting .
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If I "tap" the service conductors outside of the building then those conductors can go to an outside service disconnect and then feed the chiller that is also outdoors?
 
electrofelon said:
Augie, perhaps I am mis understanding but you would still have non grouped disconnects.
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Point taken. I may have read something into the post based on experience. I assumed the chiller is free standing and not a part of the main structure in which case I think the plan would be valid. If the chiller is not a separate entity set away from the building (a common practice locally) then I would say grouping was necessary.
 
augie47 said:
Point taken. I may have read something into the post based on experience. I assumed the chiller is free standing and not a part of the main structure in which case I think the plan would be valid. If the chiller is not a separate entity set away from the building (a common practice locally) then I would say grouping was necessary.
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The chiller is free standing and not part of the building. It's about 50 feet away from the building, just for visualization purposes.
 
xguard said:
The chiller is free standing and not part of the building. It's about 50 feet away from the building, just for visualization purposes.
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IMO, the installation I mentioned would be Code compliant. It would not be much different from having POCO bring a separate service to the chiller. Obviously that is an opinion and I would definitely run it by your AHJ.

Ethan: I light of the chiller being distant, do you still feel it would be a violation ?
 
augie47 said:
IMO, the installation I mentioned would be Code compliant. It would not be much different from having POCO bring a separate service to the chiller. Obviously that is an opinion and I would definitely run it by your AHJ.

Ethan: I light of the chiller being distant, do you still feel it would be a violation ?
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Hmmm ok, that is a tricky one. If you look at 230.40, I dont see the situation covered by any of the exceptions. What we would need is something like exception #3 but without the "single family dwelling" qualifier. One could take the philsophical stance that the NEC has no business telling us how many services can be supplied by one drop or lateral, since whats ahead of the service point is theoretically invisible to the NEC......
 
xguard said:
These unprotected conductors exit the panel and go outside to the chiller disconnect.
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Not completely related to your question. Do these unprotected conductors fall under the outside taps of unlimited length rule?

I realize this isn't a feeder. I'm just trying to understand which rule allowed the original installers to make that tap on the service conductors in the interior panel.

Is the reason that panel does not have an exterior disconnect due to the age, or location of the building?

Sent from my SM-G950U using Tapatalk
 
WarrMann said:
Not completely related to your question. Do these unprotected conductors fall under the outside taps of unlimited length rule?

I realize this isn't a feeder. I'm just trying to understand which rule allowed the original installers to make that tap on the service conductors in the interior panel.

Is the reason that panel does not have an exterior disconnect due to the age, or location of the building?

Sent from my SM-G950U using Tapatalk
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"Tap rules" for service conductors are basically in 230.40. Other rules that may come into play are grouping of disconects, and length of SEC inside allowed by AHJ.
 
electrofelon said:
"Tap rules" for service conductors are basically in 230.40. Other rules that may come into play are grouping of disconects, and length of SEC inside allowed by AHJ.
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How does 230.40, or any of 230 allow us to tap an unprotected service conductor with a smaller conductor (I'm assuming here) inside a panel that's inside a building. Then run that tapped, unprotected conductor back outside the building to what could be an indefinite length?

I don't mean to argue if that's how it sounds. Im thrown off by this one. Is this something you have seen often?

In this situation couldn't the problem be solved by taking the chiller wires and putting them in a breaker? Then we're not even talking service disconnects. Just a disconnect


Then the ground would just be out into the panels ground bar
Sent from my SM-G950U using Tapatalk
 
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WarrMann said:
How does 230.40, or any of 230 allow us to tap an unprotected service conductor with a smaller conductor (I'm assuming here) inside a panel that's inside a building. Then run that tapped, unprotected conductor back outside the building to what could be an indefinite length?

I don't mean to argue if that's how it sounds. Im thrown off by this one. Is this something you have seen often?

In this situation couldn't the problem be solved by taking the chiller wires and putting them in a breaker? Then we're not even talking service disconnects. Just a disconnect


Then the ground would just be out into the panels ground bar
Sent from my SM-G950U using Tapatalk
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This chiller was installed in 2000. It needed a 700 amp ocpd. The largest the panels could accept was 350. I'm not saying they did it right but from what I can tell based on old plans and looking at it that was the reasoning.
 
electrofelon said:
Hmmm ok, that is a tricky one. If you look at 230.40, I dont see the situation covered by any of the exceptions. What we would need is something like exception #3 but without the "single family dwelling" qualifier. One could take the philsophical stance that the NEC has no business telling us how many services can be supplied by one drop or lateral, since whats ahead of the service point is theoretically invisible to the NEC......
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"Each service drop, set of overhead service conductors, set of underground service conductors, or service lateral shall supply only one set of service-entrance conductors"

It includes more than just what is on the supply side of the service point. May need a little work on wording but I think the intent was to mean one utility supply conductor method is to supply one set of service entrance conductors. I believe this wording is still same or nearly the same as it was before they introduced the "service point" definition.

I see no problem with this section if a separate lateral/underground service conductor were run from utility to the chiller though.

xguard said:
This chiller was installed in 2000. It needed a 700 amp ocpd. The largest the panels could accept was 350. I'm not saying they did it right but from what I can tell based on old plans and looking at it that was the reasoning.
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Does the service conductors have sufficient ampacity for everything they currently supply?
 
kwired said:
"Each service drop, set of overhead service conductors, set of underground service conductors, or service lateral shall supply only one set of service-entrance conductors"

It includes more than just what is on the supply side of the service point. May need a little work on wording but I think the intent was to mean one utility supply conductor method is to supply one set of service entrance conductors. I believe this wording is still same or nearly the same as it was before they introduced the "service point" definition.

I see no problem with this section if a separate lateral/underground service conductor were run from utility to the chiller though.

Does the service conductors have sufficient ampacity for everything they currently supply?
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Yea. The one large chiller replaced two smaller chillers that were each on their own breaker. The total load is the same.
 
WarrMann said:
How does 230.40, or any of 230 allow us to tap an unprotected service conductor with a smaller conductor (I'm assuming here) inside a panel that's inside a building....
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230.33 and 230.40 exceptions.


.....Then run that tapped, unprotected conductor back outside the building to what could be an indefinite length?

I don't mean to argue if that's how it sounds. Im thrown off by this one. Is this something you have seen often?

In this situation couldn't the problem be solved by taking the chiller wires and putting them in a breaker? Then we're not even talking service disconnects. Just a disconnect
Click to expand...

That is not allowed because of 230.72.
 
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