The utility model relates to a current transformer error checking is a foldable current transformer check -up safety protection car of working a telephone switchboard fast with quick wiring unit technical field, it is including insulating frame and wheel, insulating frame includes main part frame, left frame and right frame, can overturn foldingly right and can detain the left frame in main part frame left part upper end articulated the installing of the left end of main part frame, articulated the installing of right -hand member of main part frame can be overturn foldingly left and can be detained the right frame in main part frame right part upper end. The utility model has the advantages of reasonable and compact structure, convenient to use, insulating frame not only can avoid having safety protection's effect because of the equipment electric leakage takes place the incident, can also connect the back moving as a whole with the wiring of current transformer error calibration device, check -up efficiency is improved to avoidance of repetition wiring and repeated putting, guarantees the check -up accuracy, insulating frame adopts foldable support body structure, convenient to carry.