Question two outside feeders

Are you simply trying to avoid synchronizing of the Gensets? 250.30 allows for multiple genset as long as they are run in parallel, thus giving multiple feeders.
2017 NEC 250.30
........Multiple separately derived systems that are connected in parallel shall be installed in accordance with 250.30.

As long as your gen sets are set up as SDS you can have 2 3 or more run in parallel so long as the parallel feeders terminate in the singular transfer or a singular parallel bus setup

also note 250.30(A)(1)
Exception no. 2
If a building or structure is supplied by a feeder from an outdoor separately derived system, a system bonding jumper at both the source and the first disconnecting means shall be permitted if doing so does not establish a parallel path for the grounded conductor. If a grounded conductor is used in this manner, it shall not be smaller than the size specified for the system bonding jumper but shall not be required to be larger than the ungrounded conductor(s). For the purposes of this exception, connection through the earth shall not be considered as providing a parallel path.
 
Fred B said:
Are you simply trying to avoid synchronizing of the Gensets? 250.30 allows for multiple genset as long as they are run in parallel, thus giving multiple feeders.
2017 NEC 250.30
........Multiple separately derived systems that are connected in parallel shall be installed in accordance with 250.30.

As long as your gen sets are set up as SDS you can have 2 3 or more run in parallel so long as the parallel feeders terminate in the singular transfer or a singular parallel bus setup

also note 250.30(A)(1)
Exception no. 2
If a building or structure is supplied by a feeder from an outdoor separately derived system, a system bonding jumper at both the source and the first disconnecting means shall be permitted if doing so does not establish a parallel path for the grounded conductor. If a grounded conductor is used in this manner, it shall not be smaller than the size specified for the system bonding jumper but shall not be required to be larger than the ungrounded conductor(s). For the purposes of this exception, connection through the earth shall not be considered as providing a parallel path.
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They are not in parallel and do not require synchronizing as they feed two independent switchgear lineups
 
don_resqcapt19 said:
the system is a grounded system and grounding electrodes and EGC will be required. Again what are you seeing as a problem...the drawing is not clear enough to see any details.
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In the 600A fused disconnect which are placed right where feeders from gensets enter the building you would have to have grounding electrode conductor from ground bus to the grounding electrode system per NEC 2017 Article 250.32(A)(B)?
 
hhsting said:
In the 600A fused disconnect which are placed right where feeders from gensets enter the building you would have to have grounding electrode conductor from ground bus to the grounding electrode system per NEC 2017 Article 250.32(A)(B)?
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If it is my project, I would be using the existing building grounding electrode system for this application. I would use a supply side bonding jumper between the generator and the disconnects, install the system bonding jumper in the disconnects, and run a GEC from the building grounding electrode system to the system bonding jumper. The feeder from the disconnect would include an EGC.
I don't see a choice as to using the existing building grounding electrode system as those electrodes exist as 250.50 is in Part III and that requires the use of all grounding electrodes that exist at the building. 250.32(A) references Part III of Article 250.
 
don_resqcapt19 said:
If it is my project, I would be using the existing building grounding electrode system for this application. I would use a supply side bonding jumper between the generator and the disconnects, install the system bonding jumper in the disconnects, and run a GEC from the building grounding electrode system to the system bonding jumper. The feeder from the disconnect would include an EGC.
I don't see a choice as to using the existing building grounding electrode system as those electrodes exist as 250.50 is in Part III and that requires the use of all grounding electrodes that exist at the building. 250.32(A) references Part III of Article 250.
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How? Generator would need main breaker for protection of conductors from genset to 600A disconnect. Your first secondary overcurrent protection would end in the generators. So their is no system bonding jumper load side of stand alone gensets its equipment grounding conductor. What am I missing here?

But then you bring outside feeder into building where first disconnect right where conductors enter you would need to re ground them in accordance with NEC 2017 Article 250.32?
 
hhsting said:
How? Generator would need main breaker for protection of conductors from genset to 600A disconnect. Your first secondary overcurrent protection would end in the generators. So their is no system bonding jumper load side of stand alone gensets its equipment grounding conductor. What am I missing here?

But then you bring outside feeder into building where first disconnect right where conductors enter you would need to re ground them in accordance with NEC 2017 Article 250.32?
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I would apply 240.21(B)(5).

There is always a system bonding jumper on a separately derived system and these generators are separately derived systems.

My system bonding jumper would be in the 600 amp disconnects. The GEC connection would also be at that location and I am used the existing building grounding electrode system.

The code does not provide prescriptive installation rules for all applications. Sometimes you just have to make it safe and make it work.
 
don_resqcapt19 said:
I would apply 240.21(B)(5).

There is always a system bonding jumper on a separately derived system and these generators are separately derived systems.

My system bonding jumper would be in the 600 amp disconnects. The GEC connection would also be at that location and I am used the existing building grounding electrode system.

The code does not provide prescriptive installation rules for all applications. Sometimes you just have to make it safe and make it work.
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Applying 240.21(B)(5) feeder taps means their is overcurrent protection upstream of fused disconnect switch its just big and cable amapcity small.

Any sort of upstream overcurrent protection above fused disconnect would imply you cannot do system bonding jumper at 600A disconnect it would not be first secondary overcurrent protection.

I don’t see how this would apply at all

I am not the designer and designer has provided overcurrent protection in gensets. So

So with that said he would be supply system bonding jumper in genset not 600A disconnect.

So now he would have to reground at 600A fused disconnect in compliance with NEC 2017 Article 250.32(A)(B). Correct?
 
hhsting said:
Applying 240.21(B)(5) feeder taps means their is overcurrent protection upstream of fused disconnect switch its just big and cable amapcity small.

Any sort of upstream overcurrent protection above fused disconnect would imply you cannot do system bonding jumper at 600A disconnect it would not be first secondary overcurrent protection.

I don’t see how this would apply at all

I am not the designer and designer has provided overcurrent protection in gensets. So

So with that said he would be supply system bonding jumper in genset not 600A disconnect.

So now he would have to reground at 600A fused disconnect in compliance with NEC 2017 Article 250.32(A)(B). Correct?
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The definition of feeder includes conductors from a separately derived system.

I am going to apply the outside feeder tap rule and I am not going use an OCPD at the generator, even if the generator is supplied with built in OCPD.

Since I am not using the OCPD at the generator, I will install the system bonding jumper at the 600 amp disconnect.

Not sure what you mean by "reground" as my understanding of that term is a second connection between the neutral and the earth which is not permitted.


If you would use the OCPD at the generator, then you would install the system bonding jumper at that point, and have to provide a grounding electrode system at the generator and connect the GEC at the generator. You would then run 3 ungrounded conductors, a grounded conductor, and equipment grounding conductor to the 600 amp disconnect. At that point you would connect the EGC to be building grounding electrode system and run the 3 ungrounded conductors, a grounded conductor, and equipment grounding conductor to the switch gear. Just not how I would make this installation, but that would also be code compliant.
 
don_resqcapt19 said:
The definition of feeder includes conductors from a separately derived system.

I am going to apply the outside feeder tap rule and I am not going use an OCPD at the generator, even if the generator is supplied with built in OCPD.

Since I am not using the OCPD at the generator, I will install the system bonding jumper at the 600 amp disconnect.

Not sure what you mean by "reground" as my understanding of that term is a second connection between the neutral and the earth which is not permitted.


If you would use the OCPD at the generator, then you would install the system bonding jumper at that point, and have to provide a grounding electrode system at the generator and connect the GEC at the generator. You would then run 3 ungrounded conductors, a grounded conductor, and equipment grounding conductor to the 600 amp disconnect. At that point you would connect the EGC to be building grounding electrode system and run the 3 ungrounded conductors, a grounded conductor, and equipment grounding conductor to the switch gear. Just not how I would make this installation, but that would also be code compliant.
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don_resqcapt19 said:
The definition of feeder includes conductors from a separately derived system.

I am going to apply the outside feeder tap rule and I am not going use an OCPD at the generator, even if the generator is supplied with built in OCPD.

Since I am not using the OCPD at the generator, I will install the system bonding jumper at the 600 amp disconnect.

Not sure what you mean by "reground" as my understanding of that term is a second connection between the neutral and the earth which is not permitted.


If you would use the OCPD at the generator, then you would install the system bonding jumper at that point, and have to provide a grounding electrode system at the generator and connect the GEC at the generator. You would then run 3 ungrounded conductors, a grounded conductor, and equipment grounding conductor to the 600 amp disconnect. At that point you would connect the EGC to be building grounding electrode system and run the 3 ungrounded conductors, a grounded conductor, and equipment grounding conductor to the switch gear. Just not how I would make this installation, but that would also be code compliant.
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By re-grounding i mean providing grounding electrode conductor to building grounding electrode system from 600A disconnect ground bus.

I agree that conductors between genset and 600A disconnect are feeder but NEC 2017 Article 240.21(B)(5) is feeder taps. Feeder taps imply their is overcurrent protection at main feeder. If you are not using overcurrent protection in genset then feeder taps NEC 2017 Article 240.21(B)(5) would not apply at all and you cant use that because it wouldn’t be feeder taps. Taps. If you use overcurrent protection in genset then you cant do system bonding jumper in 600A disconnect not first secondary overcurrent protection. I dont see how what you are saying works??
 
hhsting said:
By re-grounding i mean providing grounding electrode conductor to building grounding electrode system from 600A disconnect ground bus.

I agree that conductors between genset and 600A disconnect are feeder but NEC 2017 Article 240.21(B)(5) is feeder taps. Feeder taps imply their is overcurrent protection at main feeder. If you are not using overcurrent protection in genset then feeder taps NEC 2017 Article 240.21(B)(5) would not apply at all and you cant use that because it wouldn’t be feeder taps. Taps. If you use overcurrent protection in genset then you cant do system bonding jumper in 600A disconnect not first secondary overcurrent protection. I dont see how what you are saying works??
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Where does the code say that?
...Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder...
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The output terminal of the generator is a feeder.

I gave you a second option with the OCPD in the generator. In my opinion both would be code compliant and I would approve either one, but if it is my choice, there would be no OCPD at the generator.
 
don_resqcapt19 said:
Where does the code say that? The output terminal of the generator is a feeder.

I gave you a second option with the OCPD in the generator. In my opinion both would be code compliant and I would approve either one, but if it is my choice, there would be no OCPD at the generator.
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I have no question on second option but the first option is questionable.

I think the paragraph you quoted permitted to be tap without over current protection has to do with point where the tap is made you dont need overcurrent protection but upstream of that point is different story


There has to definition of tap conductors or definition of feeder taps in NEC 2017 somewhere. If there is then that should clear things up about your outside feeder tap cannot be used and not consider tap conductors.
 
hhsting said:
I have no question on second option but the first option is questionable.

I think the paragraph you quoted permitted to be tap without over current protection has to do with point where the tap is made you dont need overcurrent protection but upstream of that point is different story


There has to definition of tap conductors or definition of feeder taps in NEC 2017 somewhere. If there is then that should clear things up about your outside feeder tap cannot be used and not consider tap conductors.
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Since the definition of feeder says:
Feeder.
All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device.
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There is no upstream OCPD when the separately derived system is a generator.

You can read the code however you want to...I have told you how I read the code.
We are done, have a good day.
 
don_resqcapt19 said:
Since the definition of feeder says:

There is no upstream OCPD when the separately derived system is a generator.

You can read the code however you want to...I have told you how I read the code.
We are done, have a good day.
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c5966b47f2c1b3bd8a16111249353d3a.jpg


Please see above definition of tap conductors NEC 2017 Article 240.2.


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