Hi have a chiller rated 208V, 3P, MCA: 46.1, MOPD: 80, RLA: 30. Its been awhile for sizing motor branch ckts but any idea how to size the ckt. & OCPD?

Correct me if I am wrong but last I remember based on the nameplate info conductors can be #6 with 60A circuit breaker?
MCA = minimum current ampacity
OCPD = maximum over current protection device

Where in the NEC doesnt reference sizing ckts per nameplate?

thanks in advance

NEC Article 440 is the one you want to read for this.

You can use #8 for a MCA of 46.1, with up to an 80 amp hacr breaker or fuses for the MOPD.

#8 is good for 40A in the 60deg C column of table 310.16. I think I need to use this for equipment rated 100A or less?

Make sure the terminals in the Chiller are rated for 75° C if you plan on using #8 copper wire. Most equipment of this nature are only rated for 60° C and that would call for a #6. As for the line side of the disconnect (assume it is separate from the Chiller) it probably would be rated 75° and #8 would be fine. The 80a. overcurrent device is proper in either case.