Clamp meter voltage for 15 amps
Larry from the online info on this meter


  Klein Tools CL600 is an automatically ranging true root mean square
  (TRMS) digital clamp-meter that measures AC current via the clamp, and
  measures AC/DC voltage, resistance, continuity, and tests diodes via
  test-leads.


Do you see that the clamp is for AC current measurement. The clamp cannot give a voltage reading. Voltage reading is by the probes.