WHEN THE SHOWER IS TURNED ON THE HOLE HOUSE FUSE BLOWS?

WHEN THE SHOWER IS TURNED ON THE HOLE HOUSE FUSE BLOWS. sWITCH SHOWER OFF AND ALLS WELL AGAIN. TRITON T80. SHOWER BEEN IN SERVICE FOR SEVERAL YEARS WITH NO PROBLEM. tHE OUTSIDE CORD FOR SWITCHING ON AND OFF HAS ALSO BEEN ON FOR YEARS (RED LIGHT ON) dONT KNOW HOW TO FIX IT OR EVEN HOW TO OPEN IT TO HAVE A LOOK. sOME ADVICE WOULD BE WELCOME.