Conductor Sizing

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up_onus

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Nevada
Section 430.22 states that the minimum conductor size for leads are to be at 125% of FLA. While the protective device is set to 125% of the FLA per 430.32, if this protective device is adjustable, and has a range that is higher than the "125% rated" conductors, what do you size the conductors too?

To relate some more material from the NEC -
Section 240.4 (B) and 240.6 (B) & (C), indicate its ok size the conductors to the "adjusted" setting of the overcurrent device. It also seems to correlate that you can use the next standard size up overcurrent device.
In this case, do you have to size your conductors up for motor applications?
 

david luchini

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Connecticut
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Section 430.22 states that the minimum conductor size for leads are to be at 125% of FLA. While the protective device is set to 125% of the FLA per 430.32, if this protective device is adjustable, and has a range that is higher than the "125% rated" conductors, what do you size the conductors too?

You would still size the conductors not less than 125% of the motor FLA. The overload device cannot be adjusted above the 125% rating unless that setting is not sufficient to start the motor or carry the load.

It should be noted that the 125% for the conductors is based on the motor FLA from the Art 430 tables, and the 125% of motor FLA is based on the motor's nameplate FLA. See 430.6(A)(1) and (A)(2).
 

augie47

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Tennessee
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You most likely are aware of this, but to be on the safe side, note that 430.32 is for overload protection. Protection of the conductors selected by 430.22 from ground-fault/short circuit protection is determined by Part IV, most often 430.52.
IN a majority of cases the conductor is size at 125% of Table Values and the Fuse or Circuit Breaker for Sc/GF protection at 175%/250% respectively (From 430.52). Overload protection is most often from internal means or an overload device separate from the GF/SC device.
 

up_onus

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Location
Nevada
My worry is....

My worry is....

It is a safetly issue. That people have access to the "adjustable" over current device. If it adjusted up, that no longer protects the conductors as required.
I cant seem to find out if you need to size the conductors to the maximum of the overcurrent device? or just to the setting that is "required" and set to.
 

Dennis Alwon

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Chapel Hill, NC
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Retired Electrical Contractor
The OL protector of the motor will protect the conductor- assuming it has them. If not OL protectors would be required.
 
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