2020 master prep question

[Dsg319]

Question is asking for conductor ampacity for the following motor. My answer (could be wrong) does not come out to there’s. The way they done there’s is with the name plate current to find conductor ampacity.

I was always thought use nameplate current for OVERLOADS and FLC in the NEC for conductor ampacity.

 

[tom baker]

Yes nameplate (hP) for overloads and FLC for conductor ampacity.

 

[Dsg319]

Yes nameplate (hP) for overloads and FLC for conductor ampacity.

Yeah I’m guessing they either messed up on it, or I was missing something but not quite sure. Because to size shortcircuit/ground fault protection the nameplate (FLA) is pretty well irrelevant?

 

[texie]

In this case you do use the nameplate. Look closely at 430.22(E) and the title of Table 430.22(E). Note that is says "nameplate".

 

[Dsg319]

In this case you do use the nameplate. Look closely at 430.22(E) and the title of Table 432.22(E). Note that is says "nameplate".

Thank you! If it was a snake that one woulda bit me...

 

[Dsg319]

When sizing a main breaker on feeder conductors supplying a panel full of motor loads, do I have it the correct understanding of sizing it by largest OCPD in the group plus the FLC of the rest of the motor circuits?

Not taking into consideration of not operating simultaneously....

 

[texie]

Correct. If you had only motor load you would (3) and (4) would be moot.

 

[texie]

View attachment 2554745
When sizing a main breaker on feeder conductors supplying a panel full of motor loads, do I have it the correct understanding of sizing it by largest OCPD in the group plus the FLC of the rest of the motor circuits?

Not taking into consideration of not operating simultaneously....

Yes.

 

[texie]

Correct. If you had only motor load you would (3) and (4) would be moot.

Funny, I can no longer see your post relating to this.

 

[Dsg319]

Funny, I can no longer see your post relating to this.

Thanks. And the reason you can’t see the other post was it was I deleted it real quick because I shortly after asking found the answer.....was hoping no one noticed but guess I’m not that slick

 

[Bang]

I think that the reason you didn't get the same answer they got, is because you used a different ampacity (52.)