Series rated circuit breakers clarification

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Cartoon1

Cartoon1

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Assume all examples below are using equipment from the same manufacturer (panels, breakers, busses, etc). Assume short fault is 35k at all locations. Typically from the manufacturers I seen, square d, Cutler, Siemens. 22kaic branch breakers are usually series rated with 65kaic breakers or in some cases even higher. But some senarios makes me question that.

Example 1: if the panel main circuit breaker is rated 65kaic but the panel itself is rated 22kaic and branch breakers are rated 22kaic. Would this be considerd a series rating?

Example 2: enclosed circuit breaker rated 65kaic, feeding a main lugs only panel rated 22kaic with 22kaic branch breaker. Would this be considerd a series rating?

Thank you
 
First, your "panel itself" ratings don't make sense. The panel board itself would have a SCCR rating not AIC, and it would likely have a rating at least as high as the highest breaker that can be installed. You basically don't have to worry about the SCCR rating of the panel. I know Siemens panel boards are all rated 200k, I don't know offhand what load centers are typically rated, but I would guess at least 65k. Other than that, yes both cases would be a series rating application.

Note that for a 225/250A frame upstream device at 65k, you usually only need 10K branches. It's typically when you get above that size that you will need to bump the branches up to 22k for a series rating.
 
Cartoon1 said:
Assume all examples below are using equipment from the same manufacturer (panels, breakers, busses, etc). Assume short fault is 35k at all locations. Typically from the manufacturers I seen, square d, Cutler, Siemens. 22kaic branch breakers are usually series rated with 65kaic breakers or in some cases even higher. But some senarios makes me question that.

Example 1: if the panel main circuit breaker is rated 65kaic but the panel itself is rated 22kaic and branch breakers are rated 22kaic. Would this be considerd a series rating?

Example 2: enclosed circuit breaker rated 65kaic, feeding a main lugs only panel rated 22kaic with 22kaic branch breaker. Would this be considerd a series rating?

Thank you
Click to expand...
In general, breakers from the same manufacturer are tested in series, so they can be series rated, but that isn't always true, so if the 65KAIC breaker and the 22KAIC breaker are listed for series rating, then yes the first example would comply with series rating. keeping in mind electrofan's comment regarding SCCR of the panels. If the panel sccr was 22,000 amps, then that would not be ok.
 
Series rated devices do not need to be in the same enclosure. The length of conductors between devices are not part of the listing testing.
All manufacturers have some series ratings, but not all manufacturers have the same ratings.
 
electrofelon said:
First, your "panel itself" ratings don't make sense. The panel board itself would have a SCCR rating not AIC, and it would likely have a rating at least as high as the highest breaker that can be installed. You basically don't have to worry about the SCCR rating of the panel. I know Siemens panel boards are all rated 200k, I don't know offhand what load centers are typically rated, but I would guess at least 65k. Other than that, yes both cases would be a series rating application.

Note that for a 225/250A frame upstream device at 65k, you usually only need 10K branches. It's typically when you get above that size that you will need to bump the branches up to 22k for a series rating.
Click to expand...
Great thanks!!
 
Strathead said:
In general, breakers from the same manufacturer are tested in series, so they can be series rated, but that isn't always true, so if the 65KAIC breaker and the 22KAIC breaker are listed for series rating, then yes the first example would comply with series rating. keeping in mind electrofan's comment regarding SCCR of the panels. If the panel sccr was 22,000 amps, then that would not be ok.
Click to expand...
Gotcha, that clears things up a little.
 
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