This almost sounds like you have 2 different systems crossed... Do you have 480Y/277V in the building at all? I'm not sure how you can get 255V otherwise, especially if all is well in the panel (aside from being stablok ) Even if this were a high leg system, you'd at best have around 2o8V-G. If no ballasts are involved and your panel voltage is 208V phase to phase, you're picking up voltage from a source outside of that panel to get 255V.
) Even if this were a high leg system, you'd at best have around 2o8V-G. If no ballasts are involved and your panel voltage is 208V phase to phase, you're picking up voltage from a source outside of that panel to get 255V. 
