Pumps breaker sizing

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This is the 2017 code book


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ElectricMatt said:
You said the designer is providing a breaker that feeds the pumps. So you can base your answer off of that breaker size.

There is multiple answers for how to size your breaker for a multi motor feeder. There is different criteria in the selection which falls under the design of the circuit.

So if your looking to design a feeder for the 3 pumps you listed than I will stick with the answer I have given previously.

If you are trying to size your feeder off an assumption than you can start with 430.62(A), this is validated by 430.63(3)

If you need more specific information or are having trouble understanding the code book please specify that and many on here will be glad to help with that.


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I said designer is providing the feeder breaker that feeds Control Panel. I am looking for the feeder breaker size code section and min and max feeder breaker sizes
 
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This is the 2020 code book.

They both read the same. That is not specifically for hermetic compressors. I believe that the ….or 440.22(A) is indication that it is not specifically for hermetic compressors.


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ElectricMatt said:
05a36edd95b19635275113b97dd84ac6.jpg

This is the 2020 code book.

They both read the same. That is not specifically for hermetic compressors. I believe that the ….or 440.22(A) is indication that it is not specifically for hermetic compressors.


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Ok. Two questions:

1. If u use 430.62(A) then the branch short circuit overcurrent protection would be fuse and which has max of 175% Table 430.52. How can u use max of 250% or greater than 175%?

2. Since the feeder is supplying control panel would not 409.21(C) apply for feeder breaker sizing?


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Both would reference you back to the one designing the industrial control panel.

If you are designing the control panel it references you to 430.52

If you are installing a pre-designed panels. Then409.21(C)


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However your line of questioning seems to be deviating from a scenario you have specifically to the realm of theory.

If it’s theory, I am game for it. Just call it what it is and don’t try for disguise it as a real world scenario you need help with.


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ElectricMatt said:
5bcf69139b0a94eef57a5f1084e5b9d8.jpg


Both would reference you back to the one designing the industrial control panel.

If you are designing the control panel it references you to 430.52

If you are installing a pre-designed panels. Then409.21(C)


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Its going to be pre design factory. 409.21(C) below. If i dont know the branch short circuit overcurrent protection fuse size inside control panel but fuses are provided then i cannot use 430.52. Last paragraph below says 409.21(C) says if no branch short circuit protective device is provided then use 430.52.

So then what can be done?

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ElectricMatt said:
However your line of questioning seems to be deviating from a scenario you have specifically to the realm of theory.

If it’s theory, I am game for it. Just call it what it is and don’t try for disguise it as a real world scenario you need help with.


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Its not theory i have plans and i am plans reviewer


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ElectricMatt said:
5bcf69139b0a94eef57a5f1084e5b9d8.jpg


Both would reference you back to the one designing the industrial control panel.

If you are designing the control panel it references you to 430.52

If you are installing a pre-designed panels. Then409.21(C)


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What about post #25 question number 1? No response


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Okay fair enough. Let me think on it tonight and I will respond tomorrow. I think we can get you to the answer you need.

Just so I make sure I have all the information necessary.

You have the FLA of the three motors.

You know the conductor size you are using based off of the above information.

The designer will tell you what your upstream OCPD device will be.

There is a breaker/fuse provided in the control panel you are feeding with 3 branch circuit OCPD’s for each motor.

Is all of the above correct?


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ElectricMatt said:
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Okay fair enough. Let me think on it tonight and I will respond tomorrow. I think we can get you to the answer you need.

Just so I make sure I have all the information necessary.

You have the FLA of the three motors.

You know the conductor size you are using based off of the above information.

The designer will tell you what your upstream OCPD device will be.

There is a breaker/fuse provided in the control panel you are feeding with 3 branch circuit OCPD’s for each motor.

Is all of the above correct?


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Yes i have FLA of all three motors

Yes i know the feeder conductors size based off above

The designer does show feeder breaker size upstream of control panel on plans not sure if is oversized

There is only fuses provided as branch circuit overload according to designer by factory pre design control panel internal for each three pumps. See post #17 sketch right side internal of control panel pre design by someone factory
 
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ElectricMatt said:
Can you re phrase that question or maybe put some numbers to it. I am not sure I follow what you are asking.


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430.62(A) says to look at brach circuit overcurrent protection maximum setting or rating based on 430.52.

Well branch circuit overcurrent protection device is Fuse in control panel and when u go to Table 430.52 max u see is 175% for fuse. Where do u get 200% or 250%?
 
Maybe I missed it but what size conductors and overcurrent protection is the designer specifying on the plans?
 
hhsting said:
430.62(A) says to look at brach circuit overcurrent protection maximum setting or rating based on 430.52.

Well branch circuit overcurrent protection device is Fuse in control panel and when u go to Table 430.52 max u see is 175% for fuse. Where do u get 200% or 250%?
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Okay, so I think here you would go back to 430.52(A) which would send you to 430.52(C)(1)

I.e. you have 63a of combined motor load(not accounting for any other devices. You have a breaker rated at 157 amps, adjust to next standard size up.

Then each individual motor is allowed 36.75a fuses(40a).

A set of #4’s as the feeder.

You go step by step and break it down from total package to each individual branch circuit.

Is this what you are looking for?


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hhsting said:
430.62(A) says to look at brach circuit overcurrent protection maximum setting or rating based on 430.52.

Well branch circuit overcurrent protection device is Fuse in control panel and when u go to Table 430.52 max u see is 175% for fuse. Where do u get 200% or 250%?
Click to expand...

So what was the outcome of your question? Did you find the information you needed?


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