Does NEC "Next Size Up" rule apply to adjustable trip settings Breakers?

[I should know this by now]

I've typically thought of NEC 240.4 (B) to apply to MCCBs without adjustable trip settings. But with breakers that have said settings, can you set the LTPU to the next available setting to the wire's ampacity, provided the other parameters of the rule are followed (i.e. not a multi-outlet branch circuit and less than 800A)?

For example, if I have a 300A breaker with adjustable trip settings protecting wire rated at 230A, and the closest LTPU settings for the breaker are 195A and 240A, can I:
1) use the 240A LTPU setting, or am I required to
2) use the 195A LTPU setting, or am I required to
3) get a breaker rated no higher than the next size up from 230A?

 

[don_resqcapt19]

This was confusing so new language was added to 240.4(B)in the 2023 code to address the use of adjustable trip breakers in this application.

If the overcurrent protective device is an adjustable trip device installed in accordance with 240.4(B)(1), (B)(2), and (B)(3), it shall be permitted to be set to a value that does not exceed the next higher standard value above the ampacity of the conductors being protected as shown in Table 240.6(A) where restricted access in accordance with 240.6(C) is provided.

 

[electrofelon]

This was confusing so new language was added to 240.4(B)in the 2023 code to address the use of adjustable trip breakers in this application.

I just checked the language in the 2017, it seems straightforward that it is allowed. What did people find confusing or ambiguous?

 

[I should know this by now]

This was confusing so new language was added to 240.4(B)in the 2023 code to address the use of adjustable trip breakers in this application.

Thank you!

 

[don_resqcapt19]

I just checked the language in the 2017, it seems straightforward that it is allowed. What did people find confusing or ambiguous?

The language in 240.4(B)(3) was read as requiring the setting of the adjustable trip breaker to be the next standard size rating as found in 240.6. For example, if I had a 310 amp conductor, it was being read as requiring the adjustable trip setting to be 350 amps, even if there were settings between 310 and 350 amp available.

 

[wwhitney]

I just checked the language in the 2017, it seems straightforward that it is allowed. What did people find confusing or ambiguous?

It was actually clear that it wasn't allowed.

The language used is "The next higher standard overcurrent device rating . . . shall be permitted to be used." Rather than the more reasonable "Any rating not higher than the next higher standard overcurrent device rating . . . shall be permitted to be used."

Cheers, Wayne