Series Rating Help

aLWAYS_lEARNING-112532 said:
Series Rating help
In the image below, I have a few questions-
Assuming the manufactory has said these breakers are series rated.
1) can pnl1 lowest rated breaker be series rated to the feeder breaker?
2) can the series rating continue down to pnl3?


https://pasteboard.co/opibe0XafPjG.png
Click to expand...
Every breaker downstream of the Main feeder must be series rated with that breaker. Does it continue down? Well if all of them are already series rated with that feeder, it becomes a moot point.

Now, if in that example panel 1 was 22kA in series with the Main feeder, and panel 3 was 14kA, could you have a series rating between a feeder in panel 1 and panel 3 at 14kA, I think so, if it is documented. But in your example, there are no other feeders downstream of the Main feeder, so everything downstream of that breaker must be series rated with it.
 
I think you have to be careful. Here is what Eaton says from the following document:


Other Applications of Series Ratings
Series ratings can also be applied under the following guidelines:
■ Any FULLY RATED breaker can be applied upstream, downstream, or in the middle of any of the series ratings stated in the tables
■ Any series rating stated in the tables may have additional series rated branch breakers of the EXACT SAME TYPE further downstream in that rating

COMBINING SERIES RATINGS are allowed under certain conditions. Main and branch ratings may be combined if:
■ Breakers A, B, and C are in series respectively from main to branch. Breakers A and B series rate together. Breakers A and C series rate at the same interrupting level(or higher). It is allowable to use A, B, and C together at the A-B series rating
Click to expand...

Does one of those apply to your situation?
 
-If the manufacturer has provided a listed series rating between the feeder breaker (65kA) and the PNL1 lowest-rated breaker (14kA), then yes, it can be series-rated. This means that under a fault condition, the upstream feeder breaker would clear the fault while protecting the lower-rated breaker. However, the series rating must be explicitly tested and listed by the manufacturer.
-This depends on whether there is a listed series rating combination between each level of breakers (Feeder → PNL1 → PNL2 → PNL3). If PNL3’s lowest-rated breaker (14kA) is only series-rated with the breaker directly upstream (PNL2 MLO) and there is no listed combination that extends further up to the feeder breaker, then it cannot be considered part of the same series rating. If the manufacturer has a cascading listed series combination for all the breakers down to PNL3, then the series rating can be extended.
 
It looks like each downstream panel is fed from feed-through lugs, in which case the Feeder 1 series ratings are applicable to all panels.

As other have pointed out, series ratings cannot be cascaded, without special permission from the manufacturer. Each set of 2 breakers must stand alone.
 
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