Service Entrance ATS

[faresos]

Hello Every One:

I working on a project that has an existing 1200A Main switchboard, 480Y/277V service. The customer wishes to add a generator to backup the entire building. My thinking is as follows:

1. Provide new Service Entrance ATS, 1200A, 4P and locate adjacent to main switchboard.
2. Remove existing service conductors from utility transformer to Main switchboard.
3. Provide new feeder from utility transformer to new ATS and terminate in normal (utility) terminal lugs. The new feeder will utilize existing conduits between the transformer and switchboard but will use the main switchboard as a pulling point to get to the ATS.
4. Remove bonding jumper between neutral and ground bar in switchboard.
5. Pull new feeder from ATS load side back to switchboard.
6. Pull new feeder from generator to ATS emergency terminal side.

Is there any better (cleaner) way on doing this? I just want to make sure I'm not overthinking it. Is there anyway I can use the main switchboard as a service entrance as currently is and still can use an ATS to power the entire building?

Thanks,

 

[templdl]

Hello Every One:

I working on a project that has an existing 1200A Main switchboard, 480Y/277V service. The customer wishes to add a generator to backup the entire building. My thinking is as follows:

1. Provide new Service Entrance ATS, 1200A, 4P and locate adjacent to main switchboard.
2. Remove existing service conductors from utility transformer to Main switchboard.
3. Provide new feeder from utility transformer to new ATS and terminate in normal (utility) terminal lugs. The new feeder will utilize existing conduits between the transformer and switchboard but will use the main switchboard as a pulling point to get to the ATS.
4. Remove bonding jumper between neutral and ground bar in switchboard.
5. Pull new feeder from ATS load side back to switchboard.
6. Pull new feeder from generator to ATS emergency terminal side.

Is there any better (cleaner) way on doing this? I just want to make sure I'm not overthinking it. Is there anyway I can use the main switchboard as a service entrance as currently is and still can use an ATS to power the entire building?

Thanks,

It sound like a reasonable thing to do. In order to do the service entrance thing with an ATC you ATS must be a breaker type ATS such that the ATS can be listed as SE.

 

[ghostbuster]

Be careful---before you purchase ATS make sure it will pass all service entrance electrical inspection requirements---it may be worthwhile discussing with your local inspection group.

We had a project where the supplier claimed the ATS was service entrance rated but failed electrical inspection because according to the inpection group it was not service entrance rated.

 

[GoldDigger]

We had a project where the supplier claimed the ATS was service entrance rated but failed electrical inspection because according to the inpection group it was not service entrance rated.

I wonder whether the inspectors looked directly at the UL or other NRTL file on the product or just went by the absence of a SUSE label?

 

[faresos]

The more I think of it, it appears it will be an issue with the service conductors being running unprotected in the switchboard to the ATS utility side (it exceeds the 10ft rule). Does anyone know that we can modify the main breaker in the incoming switchboard section in such way to run the conductors from the load side of the main breaker (instead being connected to the switchboard bus) to the ATS and then from the ATS load side to the switchboard bus? I know I need to contact the vendor on this to confirm but just another idea.

 

[templdl]

Be careful---before you purchase ATS make sure it will pass all service entrance electrical inspection requirements---it may be worthwhile discussing with your local inspection group.

We had a project where the supplier claimed the ATS was service entrance rated but failed electrical inspection because according to the inpection group it was not service entrance rated.

The be SE in must comply with the UL SE requirements. As such IT WILL HAVE A SE LEBEL AFIXED TO IT. Otherwise it I'll look like a common ATS. We hen a specifying an ATS that is SE rated yu must specify the it have the SE OPTION!

 

[infinity]

The more I think of it, it appears it will be an issue with the service conductors being running unprotected in the switchboard to the ATS utility side (it exceeds the 10ft rule). Does anyone know that we can modify the main breaker in the incoming switchboard section in such way to run the conductors from the load side of the main breaker (instead being connected to the switchboard bus) to the ATS and then from the ATS load side to the switchboard bus? I know I need to contact the vendor on this to confirm but just another idea.

There is no 10' rule for service entrance conductors in the NEC. Once you route the SEC's to the ATS the switchboard is no longer service equipment therefore you cannot run the SEC's through the existing switchboard.

 

[ggunn]

The more I think of it, it appears it will be an issue with the service conductors being running unprotected in the switchboard to the ATS utility side (it exceeds the 10ft rule). Does anyone know that we can modify the main breaker in the incoming switchboard section in such way to run the conductors from the load side of the main breaker (instead being connected to the switchboard bus) to the ATS and then from the ATS load side to the switchboard bus? I know I need to contact the vendor on this to confirm but just another idea.

I have seen ATS units installed directly atop the MDP. They have a main breaker on the utility side of the switch. I don't remember if the N-G bond and the GEC were moved into its enclosure from the MDP but I suspect they were.