SE rated ATS and Panelboard

[TaraPersaud]

Hi

I have a SE rated 400 A ATS that I am installing. This will connect to the Utility and the Generator eliminating the need for any other disconnect. I have a question though. On the load side of the ATS do I connect a Panelboard with a Main Breaker or can I do so with only a Main Lug panelboard only?

 

[augie47]

Is it a 400 amp panelboard and fed with conductors rated for 400 amps
and are both the panelboard and ATS in/on the same building ?

 

[TaraPersaud]

Yes it is.

And it is in the same room.

 

[TaraPersaud]

Hi

Thanks. It is a 400 A panelboard and yes it is located in the same room.

 

[TaraPersaud]

Response

Response

Is it a 400 amp panelboard and fed with conductors rated for 400 amps

and are both the panelboard and ATS in/on the same building ?

Not sure how this forum works but I responded twice and it does not show up.

Yes it is a 400 A panelboard located in the same room.

 

[George Stolz]

Not sure what you see on your end, but you should see a message after your first couple posts letting you know that your posts have to be approved by a (flesh and blood) moderator before you will see them. It's a spam elimination measure.

You should not see a problem anymore, you have more than two posts approved.

 

[augie47]

and.....
I don't know of any NEC problem with the MLO

 

[LarryFine]

Do remember that the ATS becomes the main disco and requires that the GEC/EGC system and neutral bonding be done there, as well as a 4-wire feeder to the MLO panel, where bonding is not done (other than the enclosure to the EGC.)

 

[TaraPersaud]

Thanks to all. I now see my comments.

Larry: the last comment in brackets (other that the enclosure to the EGC). Can you please clarify.

 

[LarryFine]

Larry: the last comment in brackets (other that the enclosure to the EGC). Can you please clarify.

Yeppers. I mean the sub-panel enclosure must be bonded to the feeder EGC along with the branch-circuit EGC's. That's usually accomplished with grounding buses screwed directly to the can.

In other words, all of the system bonding is done in the ATS when it is, or contains, the service disconnect, and everything downstream requires a separate neutral and EGC; i.e., a 4-wire feeder.

Any panel downstream of the main disconnect is effectively a sub-panel, even if it's the only panel and it's fed from a main-only disconnect. I'm just pointing out that the usual sub-panel rules apply.