Wire Size

[Alwayslearningelec]

As an example circuit #11 HWP-104. the FLA is 77 amps but the fuse is 150A. So the OCPD(150a Fuse) wire needs to be sized to at least 150A? I am a little confused because the FLA is 77A. I guess your also need to add 125% to the 77A?

 

[winnie]

I presume that these are motor loads. Follow the rules of article 430.

Approximately: conductor ampacity 1.25x FLA, breaker size 1.5-2.5x FLA, but you get to review the details.

 

[d0nut]

Your conductor ampacity needs to be greater than or equal to the MCA, which for a single motor would be 125% of the FLA. Your fuse needs to be less than or equal to the MOCP. If a manufacturer gives you the MCA and MOCP, you don't need to do any additional engineering calculations.

 

[infinity]

As an example circuit #11 HWP-104. the FLA is 77 amps but the fuse is 150A. So the OCPD(150a Fuse) wire needs to be sized to at least 150A? I am a little confused because the FLA is 77A. I guess your also need to add 125% to the 77A?

View attachment 2580633

The FLA is irrelevant for sizing the conductors. The FLC from Table 430.250 times 125% will give you the minimum conductor size.