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

[nateholt]

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?

 

[jwelectric]

(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

 

[K8MHZ]

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?

Feeders are ahead of the last OCPD. Conductors supplying a motor would be branch circuit conductors.

 

[K8MHZ]

(B) is incorrect
At any rate we don?t add a percentage to a percentage

We do for PV installations, though. I know that is not the OP's question, but to allude that we never add a percentage to a percentage is not 100 percent true.

 

[augie47]

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)

 

[Smart $]

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.

 

[nateholt]

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)

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?