How to find Horse Power?

[Pizza]

30A TM CB for a 22A FLA motor? That's pretty small. I'd recomend 60A. see art 430.52

And, of course, 115% to 130% overloads (based on the 22A FLA). See art 430.32. Contrary to popular belief on this forum, the overloads do not limit the load on the motor. If the mechanical system has the motor overloaded, the only thing the overloads do is shut off the motor prior to it catching fire. If the motor is drawing too much current, fix the mechanical system.



Bummer. Maybe next time it is available

Edit to add code articles .. And clean up the stray bitstream

Please correct me if I'm wrong, I don't dabble in these situations very often.....
But the way I read 430.52 it says maximum rating, not a minimum.

Also 430.52 B just says the motor branch circuit device shall be capable of carrying starting current of the motor.
And that's it.

I read note 3 on table 430.52 also and maybe that could apply?
All the motor is used for is to pump hydronic fluid around.
I think this motor is way oversized for the application.


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[ActionDave]

Please correct me if I'm wrong, I don't dabble in these situations very often.....
But the way I read 430.52 it says maximum rating, not a minimum.

Also 430.52 B just says the motor branch circuit device shall be capable of carrying starting current of the motor.
And that's it.

Correct. You are allowed to, and often want to, go with a bigger than usual breaker for motors to handle the inrush current when the motor starts.

 

[GoldDigger]

Correct. You are allowed to, and often want to, go with a bigger than usual breaker for motors to handle the inrush current when the motor starts.

The more precise protection of the motor, and as a side effect the conductors, is then done by the overloads

 

[ActionDave]

The more precise protection of the motor, and as a side effect the conductors, is then done by the overloads

:thumbsup:

 

[kwired]

Please correct me if I'm wrong, I don't dabble in these situations very often.....
But the way I read 430.52 it says maximum rating, not a minimum.

Also 430.52 B just says the motor branch circuit device shall be capable of carrying starting current of the motor.
And that's it.

I read note 3 on table 430.52 also and maybe that could apply?
All the motor is used for is to pump hydronic fluid around.
I think this motor is way oversized for the application.


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If you can start your motor without tripping the breaker, go for it, there is no code violation.

But remember the motor will draw at least 6 times maybe even 8 to 10 times full load current briefly when first energized, this is the reason the values in 430.52 are as high as they are - to allow starting without nuisance tripping. What you actually need depends on the trip curve of the device used and other characteristics unique to each installation that may limit or even increase that surge of current at startup. A general rule for typical thermal magnetic breakers that works most of the time is to double full load current and go next standard size device higher.

 

[Pizza]

If you can start your motor without tripping the breaker, go for it, there is no code violation.

But remember the motor will draw at least 6 times maybe even 8 to 10 times full load current briefly when first energized, this is the reason the values in 430.52 are as high as they are - to allow starting without nuisance tripping. What you actually need depends on the trip curve of the device used and other characteristics unique to each installation that may limit or even increase that surge of current at startup. A general rule for typical thermal magnetic breakers that works most of the time is to double full load current and go next standard size device higher.

We fired her up today and it ran like a top, I'll keep my cingers frossed


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