We have hundreds of fluorescent fixtures (that now have LED tubes) fed by 277V 20amp circuits. Each run is fed by 12awg THHN and at each box 12/3 SJOOW cord feeds each light. I am adding a few lights in some dim areas and was told to just use the 14/3 we have on the shelf and it's ok because of the short distance to the fixtures. 14awg cord is good for 18amps with 2 CCC's, 15amps with 3 CCC's. Is this wrong? Thanks