Non-separately derived generator

[hhsting]

I have non seprately derived emergency generator. The generator has three breakers that feed three ATS downstream but no main breaker.

One of the ATS call it ATS-3 is fed from service switchboard feeder breaker. The service switchboard has main breaker and 6 feeder breakers.

Here is the thing the ATS-3 feeds 480V transformer primary which does not require neutral.

However neutral is not switched in ATS-3 and generator is not separately derived. How would one address this, neutral has to be brought to the ATS-3 from service switchboard feeder breaker and generator feeder breaker?

 

[augie47]

My first though would be since its not a SDS and you are dealing with a feeder, you don't need to have the neutral at the TS at all. Neutral-EGC bonding should have already been done at the service.

 

[hhsting]

My first though would be since its not a SDS and you are dealing with a feeder, you don't need to have the neutral at the TS at all. Neutral-EGC bonding should have already been done at the service.

For not separately derived generator neutral is not switched at ATS. Neutral goes back and ties to the normal side GE system.

If there is no neutral to bring since transformer primary is delta 480V then how does grounding and bonding work NEC 2014 250.30 generator?

 

[augie47]

If it is not a SDS, then your grounding is all through the equipment grounding conductors to the generator and other equipment . Neutrals would be handled per Art 200,and 215. 250.30 is for generators that are SDS/

 

[hhsting]

If it is not a SDS, then your grounding is all through the equipment grounding conductors to the generator and other equipment . Neutrals would be handled per Art 200,and 215. 250.30 is for generators that are SDS/

Which code section is for not SDS generator?

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[hhsting]

Not sure. 200A generator bkr to ATS in sketch. Attached sketch would be correct in terms of Generator grounding and bonding since Generator is NOT SDS and feeds 480V delta primary transformer via ATS which has no neutral brought to the ATS?

 

[hhsting]

Please anyone here have any experience regarding post #6. Is post #6 sketch NOT SDS generator considered to be ungrounded by code?

 

[publicgood]

I am going to restate some things I believe I understand/assume about the OP question:

• ATS-3 is not a service entrance ATS
• Bonding for the service is already done before it serves ATS-3
• The transformer downstream of ATS-3 is a 3-wire+G primary
  • Side note: You may reconsider if the transformer primary protection is allowed through the ATS
• Generator is non separately derived, i.e. - the N-G connection for the generator is not made
  • I assume this is because the other (2) ATSs being fed off of the generator utilize the neutral and land on 3pole ATSs (with un-switched neutrals)

Please comment to confirm my understanding. If my understand is correct, I have the following thoughts:

• Is ground fault protection being adequately addressed for the (2) 3-pole ATSs?
• There is no reason to bring a neutral to ATS-3 from generator or normal power side - why is this being done on the normal side?

 

[hhsting]

Please see RESPONSE below

I am going to restate some things I believe I understand/assume about the OP question:

• ATS-3 is not a service entrance ATS
  
  RESPONSE: ATS-3 is not service rated
  
• Bonding for the service is already done before it serves ATS-3
  
  RESPONSE: Yes bonding of service is already done before it serves
  
  
• The transformer downstream of ATS-3 is a 3-wire+G primary
  
  RESPONSE: Yes Transformer downstream is 3 wire + G primary 480V delta
  
  • Side note: You may reconsider if the transformer primary protection is allowed through the ATS
• Generator is non separately derived, i.e. - the N-G connection for the generator is not made
  
  RESPONSE: Generator is not separately derived
  
  • I assume this is because the other (2) ATSs being fed off of the generator utilize the neutral and land on 3pole ATSs (with un-switched neutrals)

Please comment to confirm my understanding. If my understand is correct, I have the following thoughts:

• Is ground fault protection being adequately addressed for the (2) 3-pole ATSs?
  
  RESPONSE: The ATS-1 feeds fire pump has neutral from generator to ATS-1. The ATS-2 feeds elevator equipment and has neutral from generator to ATS-2
  
• There is no reason to bring a neutral to ATS-3 from generator or normal power side - why is this being done on the normal side?
  
  RESPONSE: There is no neutral brought from normal service to ATS-3. Equipment grounding conductor (EGC) and phase conductors are brought normal side to ATS-3.

 

[hhsting]

I am going to restate some things I believe I understand/assume about the OP question:

• ATS-3 is not a service entrance ATS
• Bonding for the service is already done before it serves ATS-3
• The transformer downstream of ATS-3 is a 3-wire+G primary
  • Side note: You may reconsider if the transformer primary protection is allowed through the ATS
• Generator is non separately derived, i.e. - the N-G connection for the generator is not made
  • I assume this is because the other (2) ATSs being fed off of the generator utilize the neutral and land on 3pole ATSs (with un-switched neutrals)

Please comment to confirm my understanding. If my understand is correct, I have the following thoughts:

• Is ground fault protection being adequately addressed for the (2) 3-pole ATSs?
• There is no reason to bring a neutral to ATS-3 from generator or normal power side - why is this being done on the normal side?

Please see RESPONSE below

I am going to restate some things I believe I understand/assume about the OP question:

• ATS-3 is not a service entrance ATS
  
  RESPONSE: ATS-3 is not service rated
  
• Bonding for the service is already done before it serves ATS-3
  
  RESPONSE: Yes bonding of service is already done before it serves
  
  
• The transformer downstream of ATS-3 is a 3-wire+G primary
  
  RESPONSE: Yes Transformer downstream is 3 wire + G primary 480V delta
  
  • Side note: You may reconsider if the transformer primary protection is allowed through the ATS
• Generator is non separately derived, i.e. - the N-G connection for the generator is not made
  
  RESPONSE: Generator is not separately derived
  
  • I assume this is because the other (2) ATSs being fed off of the generator utilize the neutral and land on 3pole ATSs (with un-switched neutrals)

Please comment to confirm my understanding. If my understand is correct, I have the following thoughts:

• Is ground fault protection being adequately addressed for the (2) 3-pole ATSs?
  
  RESPONSE: The ATS-1 feeds fire pump has neutral from generator to ATS-1. The ATS-2 feeds elevator equipment and has neutral from generator to ATS-2
  
• There is no reason to bring a neutral to ATS-3 from generator or normal power side - why is this being done on the normal side?
  
  RESPONSE: There is no neutral brought from normal service to ATS-3. Equipment grounding conductor (EGC) and phase conductors are brought normal side to ATS-3.

• 
  
  Anyone have any thoughts regarding post #6 and above post?

 

[publicgood]

Not bringing a neutral to ATS-3 is okay, since not needed. This does not classify that downstream system as ungrounded, as it is solidly grounded upstream.

Am I missing another question?

 

[hhsting]

Not bringing a neutral to ATS-3 is okay, since not needed. This does not classify that downstream system as ungrounded, as it is solidly grounded upstream.

Am I missing another question?

I think so. The generator is not separately derived. By not brining the neutral to ATS-3 since it is not needed, is the generator considered ungrounded?

 

[augie47]

Since the generator is not a SDS it should be grounded by an equipment ground from the distribution system like any other equipment.

 

[publicgood]

I think so. The generator is not separately derived. By not brining the neutral to ATS-3 since it is not needed, is the generator considered ungrounded?

The system as a whole is solidly grounded by your normal service N-G bond, which your generator neutral is also touching.

 

[hhsting]

The system as a whole is solidly grounded by your normal service N-G bond, which your generator neutral is also touching.

Once again generator is not separately derived and the generator feeder breaker has no neutral brought to the ATS-3 since downstream transformer primay is delta 480V.

Ok so keywords everyone should read: no neutral brought to the ATS-3. Downstram is 480V delta. The generator is not SDS.

So how can you say generator neutral is also touching N-G bond? My question was generator considered ungrounded? Am I missing something?



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[publicgood]

Once again generator is not separately derived and the generator feeder breaker has no neutral brought to the ATS-3 since downstream transformer primay is delta 480V.

Ok so keywords everyone should read: no neutral brought to the ATS-3. Downstram is 480V delta. The generator is not SDS.

So how can you say generator neutral is also touching N-G bond? My question was generator considered ungrounded? Am I missing something?



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• I assume this is because the other (2) ATSs being fed off of the generator utilize the neutral and land on 3pole ATSs (with un-switched neutrals)

[/LIST]

RESPONSE: The ATS-1 feeds fire pump has neutral from generator to ATS-1. The ATS-2 feeds elevator equipment and has neutral from generator to ATS-2

...did I misunderstand, or is the neutral from ATS-1 and ATS-2 touching the normal service neutral? Or only from the generator?