NEC 220.5(B) Fractions of an Ampere and PV OCPD

[DTran86]

Hello, everyone!

I wanted to get their input on NEC 220.5(B) and if it's applicable for PV OCPD? If we have lets say 50.25A calculated with 125% included, are we safe to use a 50A OCPD? Any code references would be very much appreciated.

 

[jaggedben]

The only place I know of where the code refers to this is 220.5 and it's unclear if that can be applied to article 705. It really ought to be, be a strict reading would say it doesn't and a 50A breaker and 50A rated wiring is too small and you must upsize.

Power Control Systems could also potentially be quite useful here.

 

[DTran86]

Thanks for your insight!

 

[don_resqcapt19]

The first draft of the 2026 code adds the word "load" before calculations to make it clear the rounding only applies to load calculations.
There was a proposal to put the rounding rule in Article 110 so it would apply throughout the code, but that was rejected.

 

[jaggedben]

...
There was a proposal to put the rounding rule in Article 110 so it would apply throughout the code, but that was rejected.

(Sigh.)