overcurrent protection device and wire size rounding up

[PE (always learning)]

Hello all,

I have an issue where I have a GE breaker SFLA36AT0250 with a 70A rating plug, Spectra RMS, SRPF250A70. This breaker is feeding a panel down stream with #6 THHN wire which is rated for 65A. Using NEC 240.4 (B) I am allowed to round up to the next standard overcurrent device rating with exceptions. One of those exceptions is the breaker cannot have overload trip adjustments that can go above its rating. Technically I could install higher rating plugs up to 250A on this breaker, but I have specifically called out for the 70A rating plug to be used. Am I violating NEC 240.4 (B)?

Best Regards

 

[PE (always learning)]

Also, I know THHN is technically good for 75 amps at 90 degrees, but the terminal ratings on the breaker are only good for 75 degrees which brings my ampere rating to 65

 

[infinity]

Good question, that's a pretty poorly written code section.:slaphead:

 

[Jraef]

Hello all,

I have an issue where I have a GE breaker SFLA36AT0250 with a 70A rating plug, Spectra RMS, SRPF250A70. This breaker is feeding a panel down stream with #6 THHN wire which is rated for 65A. Using NEC 240.4 (B) I am allowed to round up to the next standard overcurrent device rating with exceptions. One of those exceptions is the breaker cannot have overload trip adjustments that can go above its rating. Technically I could install higher rating plugs up to 250A on this breaker, but I have specifically called out for the 70A rating plug to be used. Am I violating NEC 240.4 (B)?

Best Regards

Semantics.

You cannot in fact "adjust" the over current trip setting. With a 70A rating plug, the trip setting is 70A and therefore it is a 70A breaker. If you put a 90A rating plug in it, it is no longer a 70A breaker, it is a 90A breaker. If you put a 250A rating plug in there, it becomes a 250A rated circuit breaker.

I think you might be confusing the breaker FRAME SIZE (in your case 250A) with it being "adjustable" by virtue of changing the rating plugs. But that is not how it works. It's called a "rating plug" because it changes the rating of the breaker. Changing the plug is not 'adjusting", it's the same as changing the breaker rating.

 

[GoldDigger]

:thumbsup:
There is a qualitative difference between anyone with a screwdriver casually turning a screw and someone ordering a larger rating plug and using it to replace the old one.

 

[PE (always learning)]

Hello,

Thank you for the responses. I figured I was probably thinking about this one a little too hard and I do understand that the plugs have to be manually installed and not adjusted with a dial like some LSI breakers. I just wanted to make sure that the NEC's definition of "adjustable" didn't apply to current rating plugs. but I agree its just semantics

 

[Carultch]

:thumbsup:
There is a qualitative difference between anyone with a screwdriver casually turning a screw and someone ordering a larger rating plug and using it to replace the old one.

Agreed. If you need to swap part of the breaker with a new accessory to change its rating, I see that it would qualify as not adjustable, and be eligible for the next-size-up rule. But if you can simply turn a dial or adjustment knob, and not supply any new product to do so, it is adjustable.