motor feeder size

[Toros]

Hi
I am feeding a new motor with rating of 20 FLA,
Using existing cir. Breker in host panel which is 40 amp
. 200per cent of the load
I am maching feeder ampacity with the breaker that is #8 cu
I am good
here????

 

[fifty60]

Unless it is a Hermetic compressor or a low torque motor, you will need to reference the table at the back of NEC 430 to get the correct FLA for sizing your OCPD. If 20A is your nameplate you will use that only to size your motor overload if your motor does not already have internal thermal protection. Your calculations look right if you followed the above procedure for obtaining your FLA. 200% * FLA rounding down for an OCPD would abide by the code for a breaker.

I am not sure what 8cu is, but if it is #8AWG 75C rated copper conductor, then the 40A breaker would be an adequate OCPD. I guess I would need clarity on what you are meaning by feeder here.

 

[infinity]

If the tables in Article 430 say that the motor draws 20 amps then the conductors are sized by calculating {20 amps * 125% = 25 amps}, that would be your minimum conductor size (#12 THHN may work depending on a few variables). Then your OCPD could be up to 250% (table 230.52) for an inverse time CB or {20 amps * 250% = 50 amps}, .

 

[Toros]

motor wife sizing

motor wife sizing

Hi
I am feeding a new motor with rating of 20 FLA,
Using existing cir. Breker in host panel which is 40 amp
. 200per cent of the load
I am maching feeder ampacity with the breaker that is #8 cu
I am good
here????

Lets go like this
How about if i feed the motor with 20A FLA , using existing 40A brkr
With #10 thhn copper

 

[infinity]

Taking a guess it's code compliant but what is the MCA (minimum circuit ampacity) and MaxOCPD of the unit?