Are 430.22(A) and 215.2(A)(1) the same thing or applied separately?

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nateholt

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430.22(A) Single Motor - conductors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125% of motor's FLA.

215.2(A)(1) - feeder conductors shall have an ampacity not less than 100% of non-continuous load plus 125% of the continuous load.

Question: do these two mean the same thing or are these two adjustments applied separately?

Example: 100A motor rated continuous-duty
a) Assuming motor will never be used more than 2hr59min at a time, 100 x 1.25 = 125A (per 430.22(A))
b) Assuming motor will run > 3 hours at a time, 100 x 1.25 x 1.25 = 156.25A (per 430.22(A) AND 215.2(A)(1))

Are both "a" and "b" correct interpretations of these two sections of the NEC?
 
(B) is incorrect
430.22 is addressing branch circuit conductors, 430.24 addresses feeders for more than one motor. At any rate we don?t add a percentage to a percentage
 
nateholt said:
430.22(A) Single Motor - conductors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125% of motor's FLA.

215.2(A)(1) - feeder conductors shall have an ampacity not less than 100% of non-continuous load plus 125% of the continuous load.

Question: do these two mean the same thing or are these two adjustments applied separately?

Example: 100A motor rated continuous-duty
a) Assuming motor will never be used more than 2hr59min at a time, 100 x 1.25 = 125A (per 430.22(A))
b) Assuming motor will run > 3 hours at a time, 100 x 1.25 x 1.25 = 156.25A (per 430.22(A) AND 215.2(A)(1))

Are both "a" and "b" correct interpretations of these two sections of the NEC?
Click to expand...

Feeders are ahead of the last OCPD. Conductors supplying a motor would be branch circuit conductors.
 
The continuous duty adjustment will also satisfy the feeder 125%. You don't need to increase another 25%.
Note however, the term "continuous duty" with motors is not based exactly on the 3 hour rating. Take a look at
the note at the bottom of table 430.22(E)
 
As noted these are branch circuit conductors. The equivalent to 215.2(A)(1) for branch circuits is 210.19(A)(1). However, motor circuits are "exempted" from that requirement. Refer to 210.2 and Table 210.2.
 
augie47 said:
The continuous duty adjustment will also satisfy the feeder 125%. You don't need to increase another 25%.
Note however, the term "continuous duty" with motors is not based exactly on the 3 hour rating. Take a look at
the note at the bottom of table 430.22(E)
Click to expand...

Okay, I think something clicked in my head. With your comment and those from the other folks, I believe my confusion stemed from not differentiating "Feeder" conductors from "Branch" conductors. I was combining the 125% requirement for Feeders in 215.2(A)(1) on top of the 125% requirement for motor branch conductors in 430.22(A). So I was adding in an extra 25% two times when, in fact, these are two independent things (feeder and branch), both based upon the motor's common FLA value.

So, my single 100 FLA motor would require 100 x 1.25 = 125A ampacity feeder conductors. And on the other side of the OCPD would likely require 100 FLA x 1.25 = 125A ampacity branch circuit conductors (and not the derated 125A feeder value x 1.25).

Does this read like I understand it now?
 
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