430.32

[Pinnie]

Where does the code say you cant round up a fuse for motor overload protection?

 

[augie47]

There is noting in 430.32(A)(1) that allows "next size up" so you would need to round down however 430.21(C) does provide for situations where (A) is not sufficient.

 

[don_resqcapt19]

Where does the code say you cant round up a fuse for motor overload protection?

When the code language says;

This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate full-load current rating:

When the code says something like that, without an exception, that calculated value is an absolute maximum value. When using a fuse, you must select a fuse that has a rating equal to, or less than the maximum permitted rating. While the next lower standard size would be 15 amps, fuses are available in non-standard sizes and in this case you could us a FRN-R-17-1/2 fuse to get closer to the maximum permitted overload trip point.