wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Still not 100% on this one:
Change:
430.63 Rating or Setting — Motor Load and Other Load(s).
(A) Specific Load.
Where a feeder supplies a motor load and other load(s) and consists of conductor sizes in accordance with 430.24, the feeder protective device shall have a rating notless greater than that required for the sum of the other load(s) plus the following:
(1) For a single motor, the rating permitted by 430.52
(2) For a single hermetic refrigerant motor-compressor, the rating permitted by 440.22
(3) For two or more motors, the rating permitted by 430.62
Exception: Where the feeder OCPD provides the overcurrent protection for a motor control center, the provisions of 430.94 shall apply.
(B) Other Installations.
Where feeder conductors have an ampacity greater than required by 430.24, the rating or setting of the feeder OCPD shall be permitted to be based on the ampacity of the feeder conductors.
Substantiation:
For a feeder that falls under 430.63, at present there is nothing in the NEC that caps the OCPD size in relation to conductor size. 240.4 does not apply, as 240.4(G) defers to Article 430, including Part IV. So it would be NEC compliant to protect #14 copper conductors at 200A, as long as those conductors are part of a feeder that supplies both a motor and a non motor load, and the load is not more than the conductor ampacity in accordance with 215.2.
Thus surely the use of the word "less" here is an error. Also, it would be very odd to specify a minimum OCPD size based on values that elsewhere are maximum OCPD sizes (e.g. the rating permitted by 430.52). And 215.3 already covers minimum OCPD sizes.
In addition to changing "not less than" to "not greater than", this proposal duplicates the structure of 430.62. In particular, this limit on OCPD size should only apply when the conductors are sized per 430.24.
Change:
430.63 Rating or Setting — Motor Load and Other Load(s).
(A) Specific Load.
Where a feeder supplies a motor load and other load(s) and consists of conductor sizes in accordance with 430.24, the feeder protective device shall have a rating not
(1) For a single motor, the rating permitted by 430.52
(2) For a single hermetic refrigerant motor-compressor, the rating permitted by 440.22
(3) For two or more motors, the rating permitted by 430.62
Exception: Where the feeder OCPD provides the overcurrent protection for a motor control center, the provisions of 430.94 shall apply.
(B) Other Installations.
Where feeder conductors have an ampacity greater than required by 430.24, the rating or setting of the feeder OCPD shall be permitted to be based on the ampacity of the feeder conductors.
Substantiation:
For a feeder that falls under 430.63, at present there is nothing in the NEC that caps the OCPD size in relation to conductor size. 240.4 does not apply, as 240.4(G) defers to Article 430, including Part IV. So it would be NEC compliant to protect #14 copper conductors at 200A, as long as those conductors are part of a feeder that supplies both a motor and a non motor load, and the load is not more than the conductor ampacity in accordance with 215.2.
Thus surely the use of the word "less" here is an error. Also, it would be very odd to specify a minimum OCPD size based on values that elsewhere are maximum OCPD sizes (e.g. the rating permitted by 430.52). And 215.3 already covers minimum OCPD sizes.
In addition to changing "not less than" to "not greater than", this proposal duplicates the structure of 430.62. In particular, this limit on OCPD size should only apply when the conductors are sized per 430.24.
