OCPD on critical load sub panel

Status
Not open for further replies.
C

Coda

Member
Location
Greenville, SC, USA
Installing a critical load sub-panel, fed from manual gen/grid transfer switch. Transfer switch fed via either, 30A / 240V breaker from main panel, or, 30A / 240V generator. Generator has its own OCPD. Main panel breaker is obviously also an OCPD.

Question:
Does the critical load panel, also need it's own OCPD or is it acceptable to rely on the "upstream" main panel breaker and the generator breaker, for OCPD.
 
Coda said:
YES. (Same building).

This is the third attempt at replying. Apologies if they all show up (eventually) but the replies are NOT showing up even after a manual refresh of the thread's web pages.
Click to expand...
Would the reply, by any chance, have been the first post on a new display page for you? There is a known bug in the forum software in which the post count gets incremented, say from 20 to 21 when you are displaying 20 posts per page, but the forum will not allow the browser to open the second page. One workaround is to change the posts per page in your profile settings each time this happens. That forces a new page count calculation and fixes the problem temporarily.
The other likely explanation is that as a new poster your posts were waiting for moderator approval. Your original post was approved, but your follow up posts were made before the Form software had updated your status to no longer require approval.

Sent from my XT1585 using Tapatalk
 
GoldDigger said:
The other likely explanation is that as a new poster your posts were waiting for moderator approval. Your original post was approved, but your follow up posts were made before the Form software had updated your status to no longer require approval.
Click to expand...

^^ THIS

Sorry, didn't realize the server needed some time to catch up.
 
Buck Parrish said:
Is it fed from the same building?
Click to expand...

Expanding on my "yes" above:

The grid feeds this building (a single family residence) once. Grid to meter, to main panel, through 30A / 2 pole / 240V breaker, to transfer switch, to critical load panel.

The generator sits outside (obviously), and optionally powers the same building as follows: generator via power cable plugged into to power inlet box (L14-30), then to transfer switch, and of course then to critical load panel.

The generator has its own OCPD and obviously the breaker on the main panel is also an OCPD.

I propose to simply feed the critical load panel main lugs, rather than have yet another 30A / 240V breaker (OCPD) at the "top" of the critical load panel.

Obviously, each circuit on the critical load panel will also have its own breaker (120V, 20A).

However, if code requires it, or if AHJs tend to require it, then fine. (It being the critical load panel having its own "main" OCPD/breaker where it is fed from the transfer switch.)
 
If the feeder is protected at the utility end by a OCPD there is no NEC requirement for a main breaker in the subpanel.
 
Status
Not open for further replies.
Top